Nankai Logic Colloquium
Nankai Logic Colloquium
6/1/2023 1:13:58
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Dominik Kwietniak from Jagiellonian University. This talk is going to take place this Friday, June 2nd, from 4pm to 5pm(UTC+8, Beijing time).
Title: An anti-classification theorem for the topological conjugacy
problem for Cantor minimal systems
Abstract:
The isomorphism problem in dynamics dates back to a question of von
Neumann from 1932: Is it possible to classify (in some reasonable
sense) the ergodic measure-preserving diffeomorphisms of a compact
manifold up to isomorphism? We would like to study a similar problem:
let C be the Cantor set and let Min(C) stand for the space of all
minimal homeomorphisms of the Cantor set. Recall that a Cantor set
homeomorphism T is in Min(C) if every orbit of T is dense in C. We
say that S and T in Min(C) are topologically conjugate if there exists
a Cantor set homeomorphism h such that Sh=hT. We prove an
anti-classification result showing that even for very liberal
interpretations of what a "reasonable'' classification scheme might
be, a classification of minimal Cantor set homeomorphism up to
topological conjugacy is impossible. We see is as a consequence of the
following: we prove that the topological conjugacy relation of Cantor
minimal systems TopConj treated as a subset of Min(C) x Min(C) is
complete analytic. In particular, TopConj is a non-Borel subset of
Min(C) x Min(C). Roughly speaking, it means that it is impossible to
tell if two minimal Cantor set homeomorphisms are topologically
conjugate using only a countable amount of information and
computation.
Our result is proved by applying a Foreman-Rudolph-Weiss-type
construction used for an anti-classification theorem for ergodic
automorphisms of the Lebesgue space. We find a continuous map F from
the space of all subtrees over non-negative integers N with
arbitrarily long branches into the class of minimal homeomorphisms of
the Cantor set. Furthermore, F is a reduction, which means that a tree
T is ill-founded if and only if F(T) is topologically conjugate to its
inverse. Since the set of ill-founded trees with arbitrarily long
branches is a well-known example of a complete analytic set, we see
that it is essentially impossible to classify which minimal Cantor set
homeomorphisms are topologically conjugate to their inverses.
This is joint work with Konrad Deka, Felipe García-Ramos, Kosma
Kapsrzak, Philipp Kunde (all from the Jagiellonian University in
Kraków).
__________________________________________________________________________________________________
Best wishes,
Ming Xiao
Set Theory and Topology Seminar 6.06.2023 Piotr Szewczak (UKSW)
Wrocław Set Theory Seminar
5/31/2023 0:39:00
I am happy to announce that at the seminar in Set Theory and Topology (on Tuesday 06.06.2023 at 17:15 in room A.4.1 C-19 (Wrocław University of Science and Technology) the lecture:
"Totally imperfect Menger sets"
Piotr Szewczak (UKSW)
Feel free to spread this information among Your colleagues.
I'm looking forward to seeing You
Szymon Żeberski
(on behalf of the organizers, i.e. Piotr Borodulin-Nadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski and myself)
Abstract
A set of reals X is Menger if for any countable sequence of open covers of X one can pick finitely many elements from every cover in the sequence such that the chosen sets cover X. Any set of reals of cardinality smaller than the dominating number d is Menger and there is a non-Menger set of cardinality d. By the result of Bartoszyński and Tsaban, in ZFC, there is a totally imperfect (with no copy of the Cantor set inside) Menger set of cardinality d. We solve a problem, whether there is such a set of cardinality continuum. Using an iterated Sacks forcing and topological games we prove that it is consistent with ZFC that d<c and each totally imperfect Meneger set has cardinality less or equal than d.
This is a joint work with Valentin Haberl and Lyubomyr Zdomskyy.
The research was funded by the National Science Centre, Poland and the Austrian Science Found under the Weave-UNISONO call in the Weave programme, project: Set-theoretic aspects of topological selections 2021/03/Y/ST1/00122.
About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C-19.
Nankai Logic Colloquium
Nankai Logic Colloquium
5/24/2023 8:16:36
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Liuzhen Wu from the Academy of Mathematical and Systems Sciences, CAS. This talk is going to take place this Friday, May 26th, from 4pm to 5pm(UTC+8, Beijing time).
title: Definability of the nonstationary ideal on $\omega_1$
abstract: The nonstationary ideals are natural nontrivial ideals defined on all uncountable regular cardinals. In this talk, various aspects of definability of nonstationary ideals on uncountable cardinals are explored. The main focus is the definability of nonstationary ideal on $\omega_1$ ($NS_{\omega_1}$ for short) in some canonical models of set theory. In particular, under MM or (*) axiom, $NS_{\omega_1}$ is not $\Pi_1$ definable. On the other hand, it is consistent that in some model of $PFA$, $NS_{\omega_1}$ is $\Pi_1$ definable. This is based on the accumulated work of Aspero, Hoffelner, Larson, Schindler, Sun, Wu.
__________________________________________________________________________________________________
Title : The 30th Nankai Logic Colloquium --Liuzhen Wu
Time :16:00pm, May. 26, 2023 (Beijing Time)
Zoom Number : 851 5601 8255
Passcode : 136440
Link :https://us02web.zoom.us/j/85156018255?pwd=UjFUb3cwT0poY0JYakRub2kyNGdSdz09
_____________________________________________________________________
Best wishes,
Ming Xiao
Set Theory and Topology Seminar 30.05.2023 Zbigniew Lipecki
Wrocław Set Theory Seminar
5/24/2023 0:17:00
I am happy to announce that at the seminar in Set Theory and Topology (on Tuesday 30.05.2023 at 17:15 in room A.4.1 C-19 (Wrocław University of Science and Technology) the lecture:
"How noncompact is the space of Lebesgue measurable functions?"
will be presented by
Zbigniew Lipecki (IM PAN)
Feel free to spread this information among Your colleagues.
I'm looking forward to seeing You
Szymon Żeberski
(on behalf of the organizers, i.e. Piotr Borodulin-Nadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski and myself)
Abstract
The space in question is the space $\textfrak M$ of Lebesgue measurable subsets of the unit interval equipped with the usual Fr'echet--Nikodym (semi)metric. We show that there exists a sequence of elements of $\textfrak M$ such that their mutual distances are > 1/2. It seems to be an open problem whether "1/2" can be replaced here by a bigger constant C. We show that C must be smaller than 9/14. Moreover, we present a version of the problem in terms of binary codes.
About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C-19.
Charla de Justin Moore en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
5/22/2023 17:22:29
Seminario Colombo Mexicano de Teoría de Conjuntos
May 25
4:00 p.m. - 5:00 p.m. (Colombia time)
Large minimal non-$\sigma$-scattered orders
Justin T. Moore
Cornell University
Abstract.
We present new constructions of linear orders which are minimal with respect to being non-$\sigma$-scattered. Specifically, we will show that Jensen's diamond principle
implies that there is a minimal Countryman line, answering a question of Baumgartner. We will also construct the first consistent examples of minimal non-$\sigma$-scattered linear order of cardinality greater than $\aleph_1$. In fact, this can be achieved
at any successor cardinal $\kappa^+$, both via forcing constructions and via axiomatic principles which hold in Gödel's Constructible Universe. These linear order of cardinality $\kappa^+$ have the property that their square is the union of $\kappa$-many chains.
This
is joint work with James Cummings and Todd Eisworth.
This Week in Logic at CUNY
This Week in Logic at CUNY
5/21/2023 22:29:00
Hi everyone,
This will be the final edition of "This Week in Logic" for the Spring 2023 semester. Regular mailings will resume in late August. We will send out special editions for events over the summer - please send me your notifications.
Be well,
Jonas
This Week in Logic at CUNY:
- - - - Monday, May 22, 2023 - - - -
- - - - Tuesday, May 23, 2023 - - - -
MAMLS Spring Fling at Rutgers UniversityThe MAMLS Spring Fling meeting will take place May 23-26 at Rutgers University, New Brunswick, New Jersey. More information about the meeting can be found on its website (
https://sites.math.rutgers.edu/~fc327/MAMLS2023/index.html)
. Registration is free and everyone who plans to attend is encouraged to register for logistics purposes.- - - - Wednesday, May 24, 2023 - - - -
- - - - Thursday, May 25, 2023 - - - -
- - - - Friday, May 26, 2023 - - - -
- - - - Other Logic News - - - -
- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) four talks, long and short
Kurt Godel Research Center
5/18/2023 16:39:33
The KGRC welcomes as guests:
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Thilo Weinert (host: Vera Fischer) visits the KGRC from May 10 to June 30.
Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from May
13 to May 27 and gives a talk, see below.
Aaron Anderson (host: Matthias Aschenbrenner) visits the KGRC from May 23
to May 24 and gives a talk, see below.
Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and
gives a short talk, see below.
Nigel Pynn-Coates (host: Matthias Aschenbrenner) visits the KGRC from June
2 to June 10.
Ido Feldman (host: Miguel Moreno) visits the KGRC from June 11 to June 17
and gives a talk, details to be announced at a later time.
Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June
24 and gives a talk, details to be announced at a later time.
David Schrittesser (host: Vera Fischer) visits the KGRC from June 30 to
September 14.
* * *
Model Theory Seminar
Kurt Gödel Research Center
Wednesday, May 24
"Distality in Continuous Logic"
Aaron Anderson (University of California, LA, US)
We examine distal theories and structures in the context of continuous
logic, providing several equivalent definitions. By studying the
combinatorics of fuzzy VC-classes, we find continuous versions of (strong)
honest definitions and distal cell decompositions. By studying generically
stable Keisler measures in continuous logic, we apply the theory of
continuous distality to analytic versions of graph regularity.
Time and Place
Talk at 3:00pm
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Please direct any questions about this talk to
matthias.aschenbrenner@univie.ac.at.
* * *
Set Theory Seminar
Kurt Gödel Research Center
Thursday, May 25
This installment of the seminar will see two shorter talks:
"Set theory of a Suslin line"
Fabian Kaak (Universität Kiel, DE)
A Suslin line is a linear ordering, which is in some way quite similar to
the real line. We will discuss in what ways the set theory of the real
line can be adapted to a Suslin line. We give a characterization of Borel
sets of the Suslin line, look at a few cardinal characteristics and play
games on a Suslin tree.
... as well as ...
"Strong Measure Zero Sets on the Higher Cantor Space"
Nick Chapman (TU Wien)
As introduced by Borel in the early 20th century, a set of reals is strong
measure zero if it can be covered by a sequence of intervals whose lengths
shrink arbitrarily fast. This notion admits a natural generalisation in
the context of the higher Cantor space $2^\kappa$. However, contrasting
the situation on $2^\omega$, much about the behaviour of strong measure
zero sets on $2^\kappa$ is unknown; in particular, the consistency of
Borel's Conjecture in this context ("A set is strong measure zero iff it
has size at most $\kappa$") is still open.
We shall discuss a statement closely related to the Borel Conjecture: for
$\kappa$ inaccessible we will sketch the construction of a model of
$|2^\kappa| = \kappa^{++}$ and "$\forall X \subseteq 2^\kappa: X \text{ is
strong measure zero iff } |X| \leq \kappa^+$", focusing on some of the
difficulties one runs into when generalising proof strategies from the
countable case. Time permitting, we will also briefly touch on Halko's
notion of stationary strong measure zero sets.
The content of this talk is extracted from my Master thesis and is based
on earlier work by Johannes Schürz.
Time and Place
Both talks, one after the other, first talk at 11:30am, in hybrid mode:
on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about these two talks to
vera.fischer@univie.ac.at.
* * *
Logic Colloquium
Kurt Gödel Research Center
Thursday, May 25
"On Hausdorff limits of images of o-minimal families in real tori"
Sergei Starchenko (University of Notre Dame, US)
Let $\{ X_s \colon x\in S \}$ be a family of subsets of ${\mathbb R}^n$
definable in some o-minimal expansion of the real field.
Let $\Gamma \subseteq {\mathbb R}^n$ be a lattice and $\pi \colon {\mathbb
R}^n/\Gamma \to \mathbb T$ be the quotient map.
In a series of papers (published and unpublished) together with Y.Peterzil we
considered Hausdorff limits of the family $\{ \pi(X_s) \colon s\in S\}$ and
provided their description.
In this talk I describe model theoretic tools used in the description.
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
2nd floor
room HS 11
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk to
vera.fischer@univie.ac.at.
Set Theory and Topology Seminar 23.05.2023 Barnabas Farkas
Wrocław Set Theory Seminar
5/17/2023 8:51:40
I am happy to announce that at the seminar in Set Theory and Topology (on Tuesday 23.04.2023 at 17:15 in room A.4.1 C-19 (Wrocław University of Science and Technology) the lecture:
"A tool to avoid some technical forcing arguments when working with the Hechler forcing"
will be presented by
Barnabas Farkas (TU Wien)
Feel free to spread this information among Your colleagues.
I'm looking forward to seeing You
Szymon Żeberski
(on behalf of the organizers, i.e. Piotr Borodulin-Nadzieja, Paweł Krupski, Aleksandra Kwiatkowska, Grzegorz Plebanek, Robert Rałowski and myself)
Abstract
I'm going to present that virtually every result saying that finite support iterations of the Hechler forcing preserve a cardinal invariant being small and its dual being large can be reduced to a single preservation theorem. In other words, this theorem eliminates the technical forcing arguments from the proofs of these results and reduces them to easy coding exercises.
About 15 minutes before the seminar we invite you for coffee and a chat to social room A.4.1.A in C-19.
Charla de Alfredo Zaragoza en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
5/16/2023 10:29:24
Seminario Colombo Mexicano de Teoría de Conjuntos
Mayo 18
4:00 p.m. - 5:00 p.m. (hora de Colombia)
Algunos ejemplos de espacios topológicos tales que dim(X) = dim(K(X)) = 1
Alfredo Zaragoza
Universidad Michoacana de San Nicolás de Hidalgo
Resumen. En general, si tenemos
un espacio topológico X de dimensión uno, la dimensión de su hiperespacio de subconjuntos compactos K(X) con la topología de Vietoris no es finita. En esta plática presentamos varios
ejemplos de espacios topológicos X de dimensión uno tales que la dimensión de su hiperespacio K(X) también es uno.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
https://cuaieed-unam.zoom.us/j/85618820721
Cross-Alps Logic Seminar (speaker: Jacques Duparc)
Cross-Alps Logic Seminar
5/15/2023 15:26:08
On Friday 19.05.2023 at 16.00
Jacques Duparc (Université de Lausanne)
will give a talk on
The Wadge order on the Cantor Space and on the Scott Domain
Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk. The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
All the best,Vincenzo
Nankai Logic Colloquium
Nankai Logic Colloquium
5/15/2023 10:46:50
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Guozhen Shen from Wuhan University. This talk is going to take place this Friday, May 19th, from 4pm to 5pm(UTC+8, Beijing time).
Title: A surjection from square onto power
Abstract: In 1892, Cantor proved that, for all sets $A$, there are no bijections between $A$ and the power set of $A$. Cantor's construction is so explicit that it can be carried out in ZF (the Zermelo--Fraenkel set theory without the axiom of choice). In 1906, by virtue of Zermelo's well-ordering theorem, Hessenberg proved the idempotency theorem, which states that there is a bijection between $A$ and the square of $A$ for all infinite sets $A$. (Another proof of the idempotency theorem was given by Zorn in 1944 using Zorn's lemma.) In 1924, Tarski proved that the idempotency theorem is in fact equivalent to the axiom of choice. On the other hand, in 1954, Specker proved in ZF a surprising generalization of Cantor's theorem, which states that, for all infinite sets $A$, there are no injections from the power set of $A$ into the square of $A$. It is then natural to ask whether it is provable in ZF that, for all infinite sets $A$, there are no surjections from the square of $A$ onto the power set of $A$. This question is known as the dual Specker problem and was proposed by Truss in 1973. In this talk, we give a negative answer to this question; that is, the existence of an infinite set $A$ such that the square of $A$ maps onto the power set of $A$ is consistent with ZF. This is joint work with Yinhe Peng and Liuzhen Wu.
__________________________________________________________________________________________________
Title :The 29th Nankai Logic Colloquium --Guozhen Shen
Time :16:00pm, May. 19, 2023 (Beijing Time)
Zoom Number :856 2849 0880
Passcode : 073635
Link :https://us02web.zoom.us/j/85628490880?pwd=dTBrV0NLc0l1bmFTY1RHR0d0TUNDZz09
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
This Week in Logic at CUNY
5/14/2023 22:43:00
This Week in Logic at CUNY:
- - - - Monday, May 15, 2023 - - - -
Logic and Metaphysics WorkshopDate: Monday, May 15, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/Maciej Sendłak (Warsaw).
Title: Explanatory realism and counterfactuals
Abstract: In my talk, I want to propose a novel approach to the question of counterfactuals. This is grounded in two assumptions, imported from the philosophy of science. The first one has it that to explain a phenomenon is to show how it depends on something else. The second states that the correct explanation ought to be contrastive. This means that a good explanation justifies the occurrence of a phenomenon and – at the same time – excludes occurrence of some other states of affairs. I am going to argue that – together with the assumption that conditionals express a dependence relation between A and C – the above gives ground for analysis of counterfactuals. According to this proposal: “A>C” is true at the world of evaluation iff there is a relation of dependence that hold between referents of A and C, and the same relation of dependence holds in the world of evaluation.
- - - - Tuesday, May 16, 2023 - - - -
- - - - Wednesday, May 17, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Arthur Parzygnat, Nagoya University.
Date and Time: Wednesday May 17, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Inferring the past and using category theory to define retrodiction.
Abstract: Classical retrodiction is the act of inferring the past based on knowledge of the present. The primary example is given by Bayes' rule P(y|x) P(x) = P(x|y) P(y), where we use prior information, conditional probabilities, and new evidence to update our belief of the state of some system. The question of how to extend this idea to quantum systems has been debated for many years. In this talk, I will lay down precise axioms for (classical and quantum) retrodiction using category theory. Among a variety of proposals for quantum retrodiction used in settings such as thermodynamics and the black hole information paradox, only one satisfies these categorical axioms. Towards the end of my talk, I will state what I believe is the main open question for retrodiction, formalized precisely for the first time. This work is based on the preprint https://arxiv.org/abs/2210.13531 and is joint work with Francesco Buscemi.
- - - - Thursday, May 18, 2023 - - - -
- - - - Friday, May 19, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, May 19, 12:30pm NY time
Virtual: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Miha Habič, Bard College at Simon's Rock
Some old and new results on nonamalgamable forcing extensions
Fixing some countable transitive model M of set theory, we can consider its generic multiverse, the family of all models obtainable from M by taking any sequence of forcing extensions and ground models. There is an attractive similarity between the generic multiverse and the Turing degrees, but the multiverse has the drawback (or feature?) that it contains nonamalgamable models, that is, models with no common upper bound, as was observed by several people, going back to at least Mostowski. In joint work with Hamkins, Klausner, Verner, and Williams in 2019, we studied the order-theoretic properties of the generic multiverse and, among other results, gave a characterization of which partial orders embed nicely into the multiverse. I will present our results in the simplest case of Cohen forcing, as well as existing generalizations to wide forcing, and some new results on non-Cohen ccc forcings.
Next Week in Logic at CUNY:
- - - - Monday, May 22, 2023 - - - -
- - - - Tuesday, May 23, 2023 - - - -
MAMLS Spring Fling at Rutgers UniversityThe MAMLS Spring Fling meeting will take place May 23-26 at Rutgers University, New Brunswick, New Jersey. More information about the meeting can be found on its website (
https://sites.math.rutgers.edu/~fc327/MAMLS2023/index.html)
. Registration is free and everyone who plans to attend is encouraged to register for logistics purposes.- - - - Wednesday, May 24, 2023 - - - -
- - - - Thursday, May 25, 2023 - - - -
- - - - Friday, May 26, 2023 - - - -
- - - - Other Logic News - - - -
- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
Applications of Set Theory, Lodz, Poland, September 4-8 2023
Conference
5/10/2023
Dear All,
We would like to inform you about the session "Applications of Set Theory" which will be held as a part of Spanish-Polish Mathematical Meeting in Lodz, Poland, 4-8 Sep 2023.
The following people kindly agreed to speak at the session:
* Alberto Salguero Alarcón (Badajoz)
* David Aspero (Norwich)
* Antonio Aviles (Murcia)
* Taras Banakh (Lviv)
* Piotr Koszmider (Warsaw)
* Mikołaj Krupski (Murcia / Warsaw)
* Jorge López Abad (Madrid) [tentative]
* Witold Marciszewski (Warsaw)
* Arturo Martínez-Celis (Wroclaw)
* Robert Rałowski (Wroclaw)
* Grigor Sargsyan (Gdansk)
* Jacek Tryba (Gdansk)
All the informations about the conference can be found at
https://es-pl.math.uni.lodz.pl/
In particular, here
https://es-pl.math.uni.lodz.pl/second.pdf
you can find the second announcement.
The conference fee is 300 EUR (up to June 30). It covers conference materials, lunches, coffee breaks, excursions, reception on September 4th and banquet on September 7th. Ph.D. students have reduced fee (150 EUR).
There is a possibility to give a contributed talk at the session.
If you have any questions please do not hesitate to contact us.
Your sincerely,
Antonio Aviles, Piotr Borodulin-Nadzieja, Szymon Glab, Jaroslaw Swaczyna
Tagged: Alberto Salguero, David Aspero, Antonio Aviles, Taras Banakh, Piotr Koszmider, Mikołaj Krupski, Jorge López Abad, Witold Marciszewski, Arturo Martínez-Celis, Robert Rałowski, Grigor Sargsyan, Jacek Tryba
Nankai Logic Colloquium
Nankai Logic Colloquium
5/9/2023 9:41:59
lHello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Maciej Malicki from Polish Academy of Sciences. This talk is going to take place this Friday, May 12th, from 4pm to 5pm(UTC+8, Beijing time).
Title: Continuous logic and equivalence relations
Abstract: We will discuss two applications of infinitary continuous logic to Borel complexity of equivalence relations. We will characterize in model-theoretic terms essentially countable isomorphism relations on Borel classes of locally compact Polish metric structures. This gives a new proof of Kechris' theorem that orbit equivalence relations of actions of Polish locally compact groups are essentially countable. We will also show that isomorphism on such classes is always Borel reducible to graph isomorphism. This immediately answers a question of Gao and Kechris whether isometry of locally compact Polish metric spaces is reducible to graph isomorphism. The first result is joint work with Andreas Hallbäck and Todor Tsankov.
__________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 28th Nankai Logic Colloquium --Maciej Malicki
Time :16:00pm, May. 12, 2023 (Beijing Time)
Zoom Number : 880 6946 7024
Passcode : 142863
_____________________________________________________________________
Best wishes,
Ming Xiao
Charla de Jose Moncayo en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
5/8/2023 10:40:15
Seminario Colombo Mexicano de Teoría de Conjuntos
Mayo 11
4:00 p.m. - 5:00 p.m. (hora de Colombia)
Construcciones conjuntistas en modelos valuados y de Kripke
Jose R. Moncayo
Universidad Nacional de Colombia
Resumen. En
esta charla se expondrán diferentes construcciones conjuntistas que buscan generalizar los modelos V y L en lógicas residuadas.
En primer lugar, usaremos la construcción de Scott y Solovay [1] (en donde se construye un modelo booleano de la teoría
de conjuntos) para proponer dos definiciones de la noción de conjunto construible, tales que la primera terminará siendo isomorfa a V y la segunda a L.
En segundo lugar, mostraremos una generalización del trabajo de Fitting [2] sobre modelos de Kripke intuicionistas de
la teoría de conjuntos. Para esto, se usarán los modelos de Kripke residuados de Ono y Komori [3, 4]. Propondremos una generalización de la jerarquía de von Neumann en el contexto de la lógica modal residuada y mostramos una traducción de fórmulas entre esta
y una jerarquía de modelos Heyting valuados adecuados.
Referencias.
[1] Scott, D. & Solovay, R. (1967). Boolean-valued models for set theory.
[2] Fitting, M. (1969). Intuitionistic Logic, Model Theory and Forcing.
[3] Ono, H. & Komori, Y. (1985) Logics without the contraction rule.
[4] Ono, H. (1985) Semantical analysis of predicate logics without the contraction rule.
Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456
https://cuaieed-unam.zoom.us/j/85618820721
This Week in Logic at CUNY
This Week in Logic at CUNY
5/7/2023 22:30:00
This Week in Logic at CUNY:
- - - - Monday, May 8, 2023 - - - -
Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY
Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.
Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker
Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson
With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center
- - - - Tuesday, May 9, 2023 - - - -
Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY
Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.
Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker
Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson
With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center
Models of Peano Arithmetic (MOPA)Tuesday, May 9, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Mateusz Łełyk, University of Warsaw
Pathologies in Satisfaction Classes: part II
This is the second part of the talk given by Athar Abdul-Quader (Pathologically definable subsets of models of CT-), however we will make sure to make it self-contained.
The talk is centered around the following problem: when a subset of a countable and recursively saturated model M can be characterized as the set of the lengths of disjunctions on which a satisfaction class behaves correctly? More precisely: let DC(x) denote a sentence in a language of PA with a fresh binary predicate S which says 'For every disjunction d with at most x disjuncts and every assignment a, S(d,a) iff there is a disjunct d' in d such that S(d',a).' We say that X is a DC-set in (M,S) iff X is precisely the set of those numbers a such that (M,S) satisfies DC(a). We ask: given a countable and recursively saturated model M for which subsets X of M we can find a satisfaction class S such that X is a DC-set in (M,S)?
In the talk we study this problem for idempotent disjunctions, that is: disjunctions which repeat the same sentence. Let IDC(x) be DC(x) restricted to such 'idempotent' disjunctions of length x. The following is one of our core results:
Theorem: For an arbitrary countable and recursively saturated model M of PA the following conditions are equivalent:
(a) M is arithmetically saturated
(b) For every cut I in M there is a satisfaction class S such that I is an IDC-set in (M,S).
We study how this result generalizes to other propositional constructions in the place of disjunctions. The talk is based on a joint work with Athar Abdul-Quader presented in this paper from arxiv: arXiv:2303.18069v1 [math.LO] 31 Mar 2023.
- - - - Wednesday, May 10, 2023 - - - -
The Logic and Metaphysics Workshop special session
May 10th from 10:00-4:00 (NY time)
CUNY Graduate Center, Kelly Skylight Room (in person)
10:00-11:30: Heinrich Wansing (Bochum)
Title: Quantifiers in connexive logic (in general and in particular)
Abstract: Connexive logic has room for two pairs of universal and particular quantifiers: one pair are standard quantifiers; the other pair are unorthodox, but we argue, are well-motivated in the context of connexive logic. Both non-standard quantifiers have been introduced previously, but in the context of connexive logic they have a natural semantic and proof-theoretic place, and plausible natural language readings. The result are logics which are negation inconsistent but non-trivial.
Note: This is joint work with Zach Weber (Otago).
12:30-2:00: Daniel Skurt (Bochum)
Title: RNmatrices for modal logics
Abstract: In this talk we will introduce a semantics for modal logics, based on so-called restricted Nmatrices (RNmatrices). These RNmatrices, previously used in the context of paraconsistent logics, prove to be a versatile tool for generating semantics for normal and non-normal systems of modal logics. Each of these semantics have sound and complete Hilbert-style calculi. The advantage of RNmatrices is that they provide a unifying framework for modal logics with or without first-order Kripke-frame conditions.
Note: This is joint work with Marcelo Coniglio (Campinas) and Pawel Pawlowski (Ghent).
2:30-4:00: Mark Colyvan (Sydney/LMU)
Title: Explanatory and non-explanatory proofs in mathematics
Abstract: In this paper I look at the contrast between explanatory and non-explanatory proofs in mathematics. This is done with the aim of shedding light on what distinguishes the explanatory proofs. I argue that there may be more than one notion of explanation in operation in mathematics: there does not seem to be a single account that ties together the different explanatory proofs found in mathematics. I then attempt to give a characterization of the different notions of explanation in play and how these sit with accounts of explanation found in philosophy of science.
- - - - Thursday, May 11, 2023 - - - -
- - - - Friday, May 12, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Friday May 12, 2:00pm-3:30pm, Room 6417
Brian Wynne, CUNY
Recent developments in the model theory of Abelian lattice-ordered groups
An Abelian lattice-ordered group (ℓ-group) is an Abelian group with a partial ordering, invariant under translations, that is a lattice ordering. A prototypical example of an ℓ-group is C(X), the continuous real-valued functions on the topological space X with pointwise operations and ordering. Let A be the class of ℓ-groups, viewed as structures for the first-order language L={+,−,0,∧,∨}. After giving more background on ℓ-groups, I will survey what is known about the ℓ-groups existentially closed (e.c.) in A, including some new examples I constructed using Fraïssé limits. Then I will discuss some recently published work of Scowcroft concerning the ℓ-groups e.c. in W+, the class of nonzero Archimedean ℓ-groups with distinguished strong order unit (viewed as structures for L1=L∪{1}). Building on Scowcroft's results, I will present new axioms for the ℓ-groups e.c. in W+ and show how they allow one to characterize those spaces X for which (C(X),1X) is e.c. in W+.
Next Week in Logic at CUNY:
- - - - Monday, May 15, 2023 - - - -
Logic and Metaphysics WorkshopDate: Monday, May 15, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/Maciej Sendłak (Warsaw).
Title: Explanatory realism and counterfactuals
Abstract: In my talk, I want to propose a novel approach to the question of counterfactuals. This is grounded in two assumptions, imported from the philosophy of science. The first one has it that to explain a phenomenon is to show how it depends on something else. The second states that the correct explanation ought to be contrastive. This means that a good explanation justifies the occurrence of a phenomenon and – at the same time – excludes occurrence of some other states of affairs. I am going to argue that – together with the assumption that conditionals express a dependence relation between A and C – the above gives ground for analysis of counterfactuals. According to this proposal: “A>C” is true at the world of evaluation iff there is a relation of dependence that hold between referents of A and C, and the same relation of dependence holds in the world of evaluation.
- - - - Tuesday, May 16, 2023 - - - -
- - - - Wednesday, May 17, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Arthur Parzygnat, Nagoya University.
Date and Time: Wednesday May 17, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Inferring the past and using category theory to define retrodiction.
Abstract: Classical retrodiction is the act of inferring the past based on knowledge of the present. The primary example is given by Bayes' rule P(y|x) P(x) = P(x|y) P(y), where we use prior information, conditional probabilities, and new evidence to update our belief of the state of some system. The question of how to extend this idea to quantum systems has been debated for many years. In this talk, I will lay down precise axioms for (classical and quantum) retrodiction using category theory. Among a variety of proposals for quantum retrodiction used in settings such as thermodynamics and the black hole information paradox, only one satisfies these categorical axioms. Towards the end of my talk, I will state what I believe is the main open question for retrodiction, formalized precisely for the first time. This work is based on the preprint https://arxiv.org/abs/2210.13531 and is joint work with Francesco Buscemi.
- - - - Thursday, May 18, 2023 - - - -
- - - - Friday, May 19, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, May 19, 12:30pm NY time
Virtual: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Miha Habič, Bard College at Simon's Rock
Some old and new results on nonamalgamable forcing extensions
Fixing some countable transitive model M of set theory, we can consider its generic multiverse, the family of all models obtainable from M by taking any sequence of forcing extensions and ground models. There is an attractive similarity between the generic multiverse and the Turing degrees, but the multiverse has the drawback (or feature?) that it contains nonamalgamable models, that is, models with no common upper bound, as was observed by several people, going back to at least Mostowski. In joint work with Hamkins, Klausner, Verner, and Williams in 2019, we studied the order-theoretic properties of the generic multiverse and, among other results, gave a characterization of which partial orders embed nicely into the multiverse. I will present our results in the simplest case of Cohen forcing, as well as existing generalizations to wide forcing, and some new results on non-Cohen ccc forcings.
- - - - Other Logic News - - - -
- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) Set Theory Seminar talk on TUESDAY, May 9
Kurt Godel Research Center
5/4/2023 13:29:13
The KGRC welcomes as guests:
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Thilo Weinert (host: Vera Fischer) visits the KGRC until June 30 and gives
a talk, see below.
Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from May
13 to May 27 and gives a talk, details to be announced at a later time.
Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and
gives a short talk, details to be announced at a later time.
Ido Feldman (host: Miguel Moreno) visits the KGRC from June 11 to June 17
and gives a talk, details to be announced at a later time.
Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June
24 and gives a talk, details to be announced at a later time.
Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23
and gives a talk, details to be announced at a later time.
* * *
Set Theory Seminar
Kurt Gödel Research Center
TUESDAY, May 9
(Please note the unusual day and the time!)
"On Unsound Linear Orderings"
Thilo Weinert
In the Eighties Adrian Mathias introduced the notion of soundness of an
ordinal. An ordinal is sound if for any countable partition P of it only
countably many ordinals are order-types of unions of subpartitionts of P.
Mathias showed that the least unsound ordinal $\zeta$ is $\omega_1^{\omega
+ 2}$ if $\aleph_1$ can be embedded into the continuum but if $\aleph_1$ is
regular yet cannot be embedded into the continuum, $\zeta \geqslant
\omega_1^{\omega 2 + 1}$.
I am going to discuss his findings and consider the notion for the more
general class of linear orderings building on work by him, MacPherson, and
Schmerl. I am also going to mention some open problems. This is joint
ongoing work with Garrett Ervin and Jonathan Schilhan.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk to
vera.fischer@univie.ac.at.
Wednesday seminar
Prague Set Theory Seminar
5/4/2023 8:30:25
Dear all,
The seminar meets on Wednesday May 10th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
There will be no seminars during a couple of weeks after next the next
one. The seminar will more likely meet again on Wednesday June 21st.
Program: Tomas Jakl -- Game comonads and the composition methods
Composition methods are a key technique in finite model theory,
which enables modular reasoning about complex structures. Examples of
such theorems are Mostowski theorem and Feferman-Vaught theorems, which
express that logical equivalence of structures is congruent with respect
to the operations of disjoint union and products of structures. Typical
applications of composition methods in finite model theory are
Courcelle's algorithmic meta theorems.
In this talk I will give a brief overview of game comonads, a new
tool from category theory in finite model theory, and discuss how they
allow us to prove very general Feferman-Vaught-Mostowski theorems.
Comonads are the formally dual notion to monads, where the latter can be
used to describe algebraic systems over arbitrary domains. For example,
topological groups can be viewed as algebras over topological spaces.
Game comonads are an approach to creating comonads by semantically
encoding a game-theoretic description of logical equivalence. Our
approach allows us to make use of a categorical description of tensor
products and bilinear maps of vector spaces.
Best,
David
Logic Seminar 10 May 2023 17:00 hrs at NUS by Jan Baars
NUS Logic Seminar
5/3/2023 6:46:51
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 10 May 2023, 17:00 hrs
Place: NUS, Department of Mathematics, S17#04-05
Speaker: Jan Baars
Title: Generalisations of a result by Gulko on spaces of continuous functions
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Please find the abstract attached.
Cross-Alps Logic Seminar (speaker: Dima Sinapova)
Cross-Alps Logic Seminar
5/2/2023 3:51:00
On Friday 05.05.2023 at 16.00
Dima Sinapova (Rutgers University)
will give a talk on
Mutual stationarity and the failure of SCH
Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk. The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
All the best,Vincenzo
Charla de Joel Aguilar en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
5/1/2023 23:47:17
Seminario Colombo Mexicano de Teoría de Conjuntos
Mayo 4
4:00 p.m. - 5:00 p.m. (hora de Colombia)
Subespacios "grandes" de C_p(X) y sus invariantes cardinales
Joel Aguilar
Universidad Michoacana de San Nicolás de Hidalgo
Resumen. Sea C_p(X) el espacio de funciones continuas de X en R con la topología de la convergencia
puntual (para garantizar que C_p(X) sea no trivial en esta plática asumiremos que todos los espacios estudiados son de Tychonoff). Una técnica común para obtener información de un espacio X es estudiar las propiedades de sus subespacios "suficientemente grandes";
por ejemplo, un espacio con un subespacio denso y psuedocompacto tiene que ser pseudocompacto; un espacio no puede ser de Lindelöf si tiene un subespacio no-numerable, discreto y cerrado; etc. En la plática nos enfocaremos en los subespacios de C_p(X) que
también son densos en la topología uniforme y discutiremos cómo se relacionan las propiedades de estos subespacios con las de C_p(X).
Zoom meeting information.
Meeting ID: 856 1882 0721
Passcode: 123456
https://cuaieed-unam.zoom.us/j/85618820721
Nankai Logic Colloquium
Nankai Logic Colloquium
5/1/2023 22:21:23
Hello everyone,
Sorry for the interrupting again. I would like to apologize(again) for a mistake in the previous announcement. There was a serious mistake in the time mentioned. The correct time of the Nankai Logic Colloquium this week is in the afternoon, 4pm to 5pm (instead of morning mentioned in the last email), Friday Beijing time. I am very very sorry for the confuse it may cause.
The following is a corrected version of the announcement for this week:
_____________________________________________________
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Ilijas Farah from York University. This talk is going to take place this Friday, May 5th, from 4pm to 5pm(UTC+8, Beijing time).
Title: Corona rigidity
Abstract. Reduced powers associated with the Frech\'et filter are well-known to be countably saturated (that is, $\aleph_1$-saturated). Because of this the Continuum Hypothesis implies that the reduced power of every countable structure has $2^{2^{\aleph_0}}$ automorphisms, and that for such reduced powers elementary equivalence is a sufficient condition for isomorphism. On the other hand, forcing axioms imply that some reduced powers (e.g., those of finite Boolean algebras) have only trivial automorphisms while some other reduced powers are saturated and they $2^{2^{\aleph_0}}$ automorphisms, provably in ZFC (e.g., those of the 2-element cyclic group).
This begs two questions: Which structures have saturated reduced powers, provably in ZFC? For which structures forcing axioms imply the `corona rigidity', that their reduced powers have only trivial automorphisms?
I will give a complete answer to the first question and a partial (rather surprising) answer to the second.
__________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 27th Nankai Logic Colloquium --Ilijas Farah
Time :16:00pm, May. 05, 2023 (Beijing Time)
Zoom Number : 827 3827 3373
Passcode : 821730
Link :https://us02web.zoom.us/j/82738273373?pwd=ZnFYbEFUSWErcDVROFUrQnZ1WGNxZz09
_____________________________________________________________________
Best wishes,
Ming Xiao
Wednesday seminar
Prague Set Theory Seminar
5/1/2023 11:29:12
Dear all,
The seminar meets on Wednesday May 3rd at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
There is no fixed program yet. We will meet and see what are we
interested in hearing/working on.
Walk-in speakers are welcome.
Best,
David
Nankai Logic Colloquium
Nankai Logic Colloquium
5/1/2023 7:33:11
Hello everyone,
I would like to apologize for a mistake in the previous announcement. There was a typo in the time mentioned. The correct time is 9am to 10am (instead of 10pm). I am very sorry for the confuse it may cause.
The following is a corrected version of the previous email:
_____________________________________________________
This week our weekly Nankai Logic Colloquium is going to be in the morning.
Our speaker this week will be Ilijas Farah from York University. This talk is going to take place this Friday, May 5th, from 9am to 10am(UTC+8, Beijing time).
Title: Corona rigidity
Abstract. Reduced powers associated with the Frech\'et filter are well-known to be countably saturated (that is, $\aleph_1$-saturated). Because of this the Continuum Hypothesis implies that the reduced power of every countable structure has $2^{2^{\aleph_0}}$ automorphisms, and that for such reduced powers elementary equivalence is a sufficient condition for isomorphism. On the other hand, forcing axioms imply that some reduced powers (e.g., those of finite Boolean algebras) have only trivial automorphisms while some other reduced powers are saturated and they $2^{2^{\aleph_0}}$ automorphisms, provably in ZFC (e.g., those of the 2-element cyclic group).
This begs two questions: Which structures have saturated reduced powers, provably in ZFC? For which structures forcing axioms imply the `corona rigidity', that their reduced powers have only trivial automorphisms?
I will give a complete answer to the first question and a partial (rather surprising) answer to the second.
__________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 27th Nankai Logic Colloquium --Ilijas Farah
Time :9:00am, May. 05, 2023 (Beijing Time)
Zoom Number : 827 3827 3373
Passcode : 821730
Link :https://us02web.zoom.us/j/82738273373?pwd=ZnFYbEFUSWErcDVROFUrQnZ1WGNxZz09
_____________________________________________________________________
Best wishes,
Ming Xiao
Nankai Logic Colloquium
Nankai Logic Colloquium
5/1/2023 7:08:56
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
Our speaker this week will be Ilijas Farah from York University. This talk is going to take place this Friday, May 5th, from 9am to 10pm(UTC+8, Beijing time).
Title: Corona rigidity
Abstract. Reduced powers associated with the Frech\'et filter are well-known to be countably saturated (that is, $\aleph_1$-saturated). Because of this the Continuum Hypothesis implies that the reduced power of every countable structure has $2^{2^{\aleph_0}}$ automorphisms, and that for such reduced powers elementary equivalence is a sufficient condition for isomorphism. On the other hand, forcing axioms imply that some reduced powers (e.g., those of finite Boolean algebras) have only trivial automorphisms while some other reduced powers are saturated and they $2^{2^{\aleph_0}}$ automorphisms, provably in ZFC (e.g., those of the 2-element cyclic group).
This begs two questions: Which structures have saturated reduced powers, provably in ZFC? For which structures forcing axioms imply the `corona rigidity', that their reduced powers have only trivial automorphisms?
I will give a complete answer to the first question and a partial (rather surprising) answer to the second.
__________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 27th Nankai Logic Colloquium --Ilijas Farah
Time :9:00am, May. 05, 2023 (Beijing Time)
Zoom Number : 827 3827 3373
Passcode : 821730
Link :https://us02web.zoom.us/j/82738273373?pwd=ZnFYbEFUSWErcDVROFUrQnZ1WGNxZz09
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
This Week in Logic at CUNY
4/30/2023 22:38:00
This Week in Logic at CUNY:
- - - - Monday, May 1, 2023 - - - -
Logic and Metaphysics WorkshopDate: Monday, May 1, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Samara Burns (Columbia).
Title: Understanding (and) surveyability
Abstract: In this talk I will discuss the notion of surveyable proof. Discussions of surveyability emerge periodically in recent philosophical literature, but the notion of surveyable proof can be traced back to Descartes. Despite this long history, there is still disagreement about what features a proof must have in order to count as surveyable. This disagreement arises, in part, because there is still significant vagueness regarding the problem that unsurveyability poses for the epistemology of mathematics. I identify three features of justification in mathematics that could be at issue in the surveyability debate: a priority, internalism, and certainty. Each of these features is prima facie troubled by unsurveyable proof. In each case, however, I’ll argue that unsurveyable proof does not pose any real issue. I will suggest that the surveyability debate should not be framed in terms of justification at all, and that the problem is really about mathematical understanding.
- - - - Tuesday, May 2, 2023 - - - -
- - - - Wednesday, May 3, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Gemma De las Cuevas, University of Innsbruck.
Date and Time: Wednesday May 3, 2023, 7:00 - 8:30 PM. ZOOM TALK.
Title: A framework for universality across disciplines.
Abstract: What is the scope of universality across disciplines? And what is its relation to undecidability? To address these questions, we build a categorical framework for universality. Its instances include Turing machines, spin models, and others. We introduce a hierarchy of universality and argue that it distinguishes universal Turing machines as a non-trivial form of universality. We also outline the relation to undecidability by drawing a connection to Lawvere’s Fixed Point Theorem. Joint work with Sebastian Stengele, Tobias Reinhart and Tomas Gonda.
- - - - Thursday, May 4, 2023 - - - -
- - - - Friday, May 5, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
NOTE UPDATED TIME: Friday, May 5, 10:00am NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Realizing Frege's Basic Law V, provably in ZFC
The standard set-theoretic distinction between sets and classes instantiates in important respects the Fregean distinction between objects and concepts, for in set theory we commonly take the universe of sets as a realm of objects to be considered under the guise of diverse concepts, the definable classes, each serving as a predicate on that domain of individuals. Although it is commonly held that in a very general manner, there can be no association of classes with objects in a way that fulfills Frege's Basic Law V, nevertheless, in the ZF framework, it turns out that we can provide a completely deflationary account of this and other Fregean abstraction principles. Namely, there is a mapping of classes to objects, definable in set theory in senses I shall explain (hence deflationary), associating every first-order parametrically definable class F with a set object εF, in such a way that Basic Law V is fulfilled:
εF=εG↔∀x(Fx↔Gx).Russell's elementary refutation of the general comprehension axiom, therefore, is improperly described as a refutation of Basic Law V itself, but rather refutes Basic Law V only when augmented with powerful class comprehension principles going strictly beyond ZF. The main result leads also to a proof of Tarski's theorem on the nondefinability of truth as a corollary to Russell's argument. A central goal of the project is to highlight the issue of definability and deflationism for the extension assignment problem at the core of Fregean abstraction.
Logic Workshop
CUNY Graduate Center
Friday May 5, 2:00pm-3:30pm, Room 6417
Karen Lange, Wellesley College
Classification via effective lists
'Classifying' a natural collection of structures is a common goal in mathematics. Providing a classification can mean different things, e.g., identifying a set of invariants that settle the isomorphism problem or creating a list of all structures of a given kind without repetition of isomorphism type. Here we discuss recent work on classifications of the latter kind from the perspective of computable structure theory. We’ll consider natural classes of computable structures such as vector spaces, equivalence relations, algebraic fields, and trees to better understand the nuances of classification via effective lists and its relationship to other forms of classification in this setting.
Next Week in Logic at CUNY:
- - - - Monday, May 8, 2023 - - - -
Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY
Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.
Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker
Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson
With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center
- - - - Tuesday, May 9, 2023 - - - -
Saul Kripke Memorial Conference
The Saul Kripke Center and CUNY Graduate Center
May 8-9, 2023, 9am-5pm, The Elebash Recital Hall, Graduate Center, CUNY
Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.
Lectures:
Romina Birman, Paul Boghossian, Harry Field, Melvin
Fitting, Daniel Isaacson, Carl Posy, Robert Stalnaker
Reminiscences:
Eduardo Barrio, James Burgess, David Chalmers, Mircea
Dumitru, Margaret Gilbert, Anandi Hattiangadi, Antonella
Mallozzi, Oliver Marshall, Yiannis Moschovakis, Stephen
Neale, Gary Ostertag, David Papineau, Graham Priest, Scott
Soames, Larry Tribe, Timothy Williamson
With an introduction by:
Steve Everett, Provost and Senior Vice President, The CUNY Graduate Center
Models of Peano Arithmetic (MOPA)Tuesday, May 9, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)
Mateusz Łełyk, University of Warsaw
Pathologies in Satisfaction Classes: part II
This is the second part of the talk given by Athar Abdul-Quader (Pathologically definable subsets of models of CT-), however we will make sure to make it self-contained.
The talk is centered around the following problem: when a subset of a countable and recursively saturated model M can be characterized as the set of the lengths of disjunctions on which a satisfaction class behaves correctly? More precisely: let DC(x) denote a sentence in a language of PA with a fresh binary predicate S which says 'For every disjunction d with at most x disjuncts and every assignment a, S(d,a) iff there is a disjunct d' in d such that S(d',a).' We say that X is a DC-set in (M,S) iff X is precisely the set of those numbers a such that (M,S) satisfies DC(a). We ask: given a countable and recursively saturated model M for which subsets X of M we can find a satisfaction class S such that X is a DC-set in (M,S)?
In the talk we study this problem for idempotent disjunctions, that is: disjunctions which repeat the same sentence. Let IDC(x) be DC(x) restricted to such 'idempotent' disjunctions of length x. The following is one of our core results:
Theorem: For an arbitrary countable and recursively saturated model M of PA the following conditions are equivalent:
(a) M is arithmetically saturated
(b) For every cut I in M there is a satisfaction class S such that I is an IDC-set in (M,S).
We study how this result generalizes to other propositional constructions in the place of disjunctions. The talk is based on a joint work with Athar Abdul-Quader presented in this paper from arxiv: arXiv:2303.18069v1 [math.LO] 31 Mar 2023.
- - - - Wednesday, May 10, 2023 - - - -
The Logic and Metaphysics Workshop special session
May 10th from 10:00-4:00 (NY time)
CUNY Graduate Center, Kelly Skylight Room (in person)
10:00-11:30: Heinrich Wansing (Bochum)
Title: Quantifiers in connexive logic (in general and in particular)
Abstract: Connexive logic has room for two pairs of universal and particular quantifiers: one pair are standard quantifiers; the other pair are unorthodox, but we argue, are well-motivated in the context of connexive logic. Both non-standard quantifiers have been introduced previously, but in the context of connexive logic they have a natural semantic and proof-theoretic place, and plausible natural language readings. The result are logics which are negation inconsistent but non-trivial.
Note: This is joint work with Zach Weber (Otago).
12:30-2:00: Daniel Skurt (Bochum)
Title: RNmatrices for modal logics
Abstract: In this talk we will introduce a semantics for modal logics, based on so-called restricted Nmatrices (RNmatrices). These RNmatrices, previously used in the context of paraconsistent logics, prove to be a versatile tool for generating semantics for normal and non-normal systems of modal logics. Each of these semantics have sound and complete Hilbert-style calculi. The advantage of RNmatrices is that they provide a unifying framework for modal logics with or without first-order Kripke-frame conditions.
Note: This is joint work with Marcelo Coniglio (Campinas) and Pawel Pawlowski (Ghent).
2:30-4:00: Mark Colyvan (Sydney/LMU)
Title: Explanatory and non-explanatory proofs in mathematics
Abstract: In this paper I look at the contrast between explanatory and non-explanatory proofs in mathematics. This is done with the aim of shedding light on what distinguishes the explanatory proofs. I argue that there may be more than one notion of explanation in operation in mathematics: there does not seem to be a single account that ties together the different explanatory proofs found in mathematics. I then attempt to give a characterization of the different notions of explanation in play and how these sit with accounts of explanation found in philosophy of science.
- - - - Thursday, May 11, 2023 - - - -
- - - - Friday, May 12, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Friday May 12, 2:00pm-3:30pm, Room 6417
Brian Wynne, CUNY
Recent developments in the model theory of Abelian lattice-ordered groups
An Abelian lattice-ordered group (ℓ-group) is an Abelian group with a partial ordering, invariant under translations, that is a lattice ordering. A prototypical example of an ℓ-group is C(X), the continuous real-valued functions on the topological space X with pointwise operations and ordering. Let A be the class of ℓ-groups, viewed as structures for the first-order language L={+,−,0,∧,∨}. After giving more background on ℓ-groups, I will survey what is known about the ℓ-groups existentially closed (e.c.) in A, including some new examples I constructed using Fraïssé limits. Then I will discuss some recently published work of Scowcroft concerning the ℓ-groups e.c. in W+, the class of nonzero Archimedean ℓ-groups with distinguished strong order unit (viewed as structures for L1=L∪{1}). Building on Scowcroft's results, I will present new axioms for the ℓ-groups e.c. in W+ and show how they allow one to characterize those spaces X for which (C(X),1X) is e.c. in W+.
- - - - Other Logic News - - - -
CONFERENCE ANNOUNCEMENT
Saul Kripke Memorial Conference
May 8-9, 2023
The Saul Kripke Center and CUNY Graduate Center
The Saul Kripke Center will host a memorial conference honoring Saul Kripke (1940-2022) at The CUNY Graduate Center on May 8th and 9th, 2023. The conference program is available here. Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) two talks on Thursday, May 4
Kurt Godel Research Center
4/27/2023 15:42:12
The KGRC welcomes as guests:
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Heike Mildenberger (host: Vera Fischer) visits the KGRC from May 3 to May
6 and gives a talk on May 4, see below.
Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and
gives a short talk, details to be announced at a later time.
Ido Feldman (host: Miguel Moreno) visits the KGRC from June 11 to June 17
and gives a talk, details to be announced at a later time.
Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June
24 and gives a talk, details to be announced at a later time.
Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23
and gives a talk, details to be announced at a later time.
* * *
Set Theory Seminar
Kurt Gödel Research Center
Thursday, May 4
"Coding with localization forcing and generalized descriptive set theory"
Lyubomyr Zdomskyy (TU Wien)
There are many known ways how to make various objects definable by
designing a suitable description for them with the help of forcing. One of
such methods is based on so-called localization invented by R. David and
further developed by S. Friedman, V. Fischer, D. Schrittesser, and many
others. We shall discuss the application of this method to the study of
Borel* subsets of 2^kappa for a successor cardinal kappa.
Joint work with Miguel Moreno.
Time and Place
Talk at 11:30am in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk to
vera.fischer@univie.ac.at.
* * *
Logic Colloquium
Kurt Gödel Research Center
Thursday, May 4
"Destroying Guessing Principles"
Heike Mildenberger (University of Freiburg, DE)
An Ostaszewski club sequence is a weakening of Jensen's diamond. In
contrast to the diamond, the club does not imply the continuum hypothesis.
Numerous questions about the club stay open, and we know only few models
in which there is just a club sequence but no diamond sequence. In recent
joint work with Shelah we found that a winning strategy for the
completeness player in a bounding game on a forcing order does not suffice
to establish the club in the extension.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
2nd floor
room HS 11
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk to
vera.fischer@univie.ac.at.
Charla de Diana Montoya en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
4/24/2023 12:45:11
Seminario Colombo Mexicano de Teoría de Conjuntos
Abril 27
4:00 p.m. - 5:00 p.m. (hora de Colombia)
Cardinales característicos en
el caso no enumerable
Diana C. Montoya
Universidad Técnica de Viena
Resumen. En
la primera parte de esta charla, presentaré la motivación y algunos resultados generales de la teoría de cardinales característicos en los espacios de Baire generalizados $\kappa^\kappa$; asimismo, presentaré un resumen del estado del arte actual de este tema.
En la segunda parte, me enfocaré en el concepto de independencia maximal en estos espacios para el caso en el cual $\kappa$ es un cardinal regular (medible), y también en el caso en el que $\kappa$ es singular. Al final, mencionaré algunas preguntas abiertas
y futuras líneas de investigación.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
Nankai Logic Colloquium
Nankai Logic Colloquium
4/23/2023 22:37:51
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
Our speaker this week will be Ronnie Chen from the University of Michigan. This talk is going to take place this Friday, Apr 28th, from 9am to 10pm(UTC+8, Beijing time).
Title: Topology versus Borel structure for actions
Abstract: A "nice" (e.g., Polish) topology contains a lot more structure than its induced Borel $\sigma$-algebra. On the other hand, Pettis's theorem says that a Polish group topology is completely determined by its induced Borel group structure. The Becker--Kechris theorem interpolates between these two extreme behaviors in the context of group actions, by characterizing the compatible topologies on a Borel $G$-space. We give a new proof of a strengthened version of the core ingredient in the Becker--Kechris theorem, that clarifies its connection to several other results in the theory of Polish group actions, as well as generalizing cleanly to other contexts such as non-Hausdorff spaces, Borel first-order $G$-structures, and groupoid actions.
__________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 26th Nankai Logic Colloquium --Ronnie Chen
Time :9:00am, Apr. 28, 2023 (Beijing Time)
Zoom Number : 840 0998 2925
Passcode : 553830
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
This Week in Logic at CUNY
4/23/2023 22:27:00
This Week in Logic at CUNY:
- - - - Monday, Apr 24, 2023 - - - -
Rutgers Logic Seminar
Monday, April 24, 2pm, Rutgers University, Hill 005
Aristotelis Panagiotopoulos, CMU
Logic and Metaphysics WorkshopDate: Monday, April 24, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/Andrea Iacona (Turin).
Title: Inferentialism and connexivity
Abstract: In my talk I will investigate the relationships between two claims about conditionals that by and large are discussed separately. One is the claim that a conditional holds when its consequent can be inferred from its antecedent, or when the latter provides a reason for accepting the former. The other is the claim that conditionals intuitively obey some characteristic connexive principles, such as Aristotle’s Thesis and Boethius Thesis. Following a line of thought that goes back to Chrysippus, I will suggest that these two claims may coherently be understood as distinct manifestations of a single basic idea, namely, that a conditional holds when its antecedent is incompatible with the negation of its consequent. The account of conditionals that I will outline is based precisely on this idea.
- - - - Tuesday, Apr 25, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, April 25, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Mateusz Łełyk University of Warsaw
Pathologies in Satisfaction Classes
This is the second part of the talk given by Athar Abdul-Quader (Pathologically definable subsets of models of CT-), however we will make sure to make it self-contained.
The talk is centered around the following problem: when a subset of a countable and recursively saturated model M can be characterized as the set of the lengths of disjunctions on which a satisfaction class behaves correctly? More precisely: let DC(x) denote a sentence in a language of PA with a fresh binary predicate S which says 'For every disjunction d with at most x disjuncts and every assignment a, S(d,a) iff there is a disjunct d' in d such that S(d',a).' We say that X is a DC-set in (M,S) iff X is precisely the set of those numbers a such that (M,S) satisfies DC(a). We ask: given a countable and recursively saturated model M for which subsets X of M we can find a satisfaction class S such that X is a DC-set in (M,S)?
In the talk we study this problem for idempotent disjunctions, that is: disjunctions which repeat the same sentence. Let IDC(x) be DC(x) restricted to such 'idempotent' disjunctions of length x. The following is one of our core results:
Theorem: For an arbitrary countable and recursively saturated model M of PA the following conditions are equivalent:
(a) M is arithmetically saturated
(b) For every cut I in M there is a satisfaction class S such that I is an IDC-set in (M,S).
We study how this result generalizes to other propositional constructions in the place of disjunctions. The talk is based on a joint work with Athar Abdul-Quader presented in this paper from arxiv: arXiv:2303.18069v1 [math.LO] 31 Mar 2023.
- - - - Wednesday, Apr 26, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Dusko Pavlovic, University of Hawai‘i at Mānoa.
Date and Time: Wednesday April 26, 2023, 7:00 - 8:30 PM. ZOOM TALK.
Title: Program-closed categories.
Abstract: > Let CC be a symmetric monoidal category with a comonoid on every object. Let CC* be the cartesian subcategory with the same objects and just the comonoid homomorphisms. A *programming language* is a well-ordered object P with a *program closure*: a family of X-natural surjections
CC(XA,B) <<--run_X-- CC*(X,P)
one for every pair A,B. In this talk, I will sketch a proof that program closure is a property: Any two programming languages are isomorphic along run-preserving morphisms. The result counters Kleene's interpretation of the Church-Turing Thesis, which has been formalized categorically as the suggestion that computability is a structure, like a group presentation, and not a property, like completeness. We prove that it is like completeness. The draft of a book on categorical computability is available from the web site dusko.org.
- - - - Thursday, Apr 27, 2023 - - - -
- - - - Friday, Apr 28, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, April 28, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Will Boney Texas State University
Next Week in Logic at CUNY:
- - - - Monday, May 1, 2023 - - - -
- - - - Tuesday, May 2, 2023 - - - -
- - - - Wednesday, May 3, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Gemma De las Cuevas, University of Innsbruck.
Date and Time: Wednesday May 3, 2023, 7:00 - 8:30 PM. ZOOM TALK.
Title: A framework for universality across disciplines.
Abstract: What is the scope of universality across disciplines? And what is its relation to undecidability? To address these questions, we build a categorical framework for universality. Its instances include Turing machines, spin models, and others. We introduce a hierarchy of universality and argue that it distinguishes universal Turing machines as a non-trivial form of universality. We also outline the relation to undecidability by drawing a connection to Lawvere’s Fixed Point Theorem. Joint work with Sebastian Stengele, Tobias Reinhart and Tomas Gonda.
- - - - Thursday, May 4, 2023 - - - -
- - - - Friday, May 5, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, May 5, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Joel David Hamkins Notre Dame University
Logic Workshop
CUNY Graduate Center
Friday May 5, 2:00pm-3:30pm, Room 6417
Karen Lange, Wellesley College
Classification via effective lists
'Classifying' a natural collection of structures is a common goal in mathematics. Providing a classification can mean different things, e.g., identifying a set of invariants that settle the isomorphism problem or creating a list of all structures of a given kind without repetition of isomorphism type. Here we discuss recent work on classifications of the latter kind from the perspective of computable structure theory. We’ll consider natural classes of computable structures such as vector spaces, equivalence relations, algebraic fields, and trees to better understand the nuances of classification via effective lists and its relationship to other forms of classification in this setting.
- - - - Other Logic News - - - -
CONFERENCE ANNOUNCEMENT
Saul Kripke Memorial Conference
May 8-9, 2023
The Saul Kripke Center and CUNY Graduate Center
The Saul Kripke Center will host a memorial conference honoring Saul Kripke (1940-2022) at The CUNY Graduate Center on May 8th and 9th, 2023. The conference program is available here. Registration for attending in person is not required, but attendees will have to comply with the Graduate Center’s Building Access Policy. Although the conference will be a mainly in person event, a livestream is also available; for this, please register.- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
(KGRC) talks in the Set Theory Seminar on April 25 and April 27
Kurt Godel Research Center
4/20/2023 12:28:38
The KGRC welcomes as guests:
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from
April 16 to April 30 and gives a talk, details to be announced at a later
time.
Tomasz Żuchowski (host: Damian Sobota) visits the KGRC from
April 24 to April 30 and gives a talk, see below.
Heike Mildenberger (host: Vera Fischer) visits the KGRC from May 3 to May
6 and gives a talk on May 4, details to be announced at a later time.
Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and
gives a short talk, details to be announced at a later time.
Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June
24 and gives a talk, details to be announced at a later time.
Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23
and gives a talk, details to be announced at a later time.
* * *
Set Theory Seminar
Kurt Gödel Research Center
Tuesday, April 25
"Nonseparable growth of $\omega$ supporting a strictly positive measure"
Tomasz Żuchowski (University of Wrocław, PL)
During the talk I will present a construction in ZFC of a compactification
of $\omega$ such that its remainder is not separable and carries a
strictly positive measure, i.e. measure positive on nonempty open subsets.
The measure is defined using the asymptotic density of subsets of
$\omega$. The remainder is a Stone space of some Boolean subalgebra of
Borel subsets of the Cantor space containing all clopen sets, constructed
with an aid of an uncountable almost disjoint family of subsets of
$\omega$. This is a joint work with Piotr Borodulin-Nadzieja.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk to
vera.fischer@univie.ac.at.
* * *
Set Theory Seminar
Kurt Gödel Research Center
Thursday, April 27
"Cardinalities of sets of reals satisfying combinatorial covering properties"
Lyubomyr Zdomskyy (TU Wien)
We shall discuss which cardinalities sets of reals satisfying Menger and
Hurewicz covering properties may have in some standard models of ZFC. Most
of the results may be thought of as consistent instances of the Perfect
Set Property, since they state that in some models, a set of reals
satisfying certain covering properties either contains a copy of the
Cantor set, or has small size. In particular, we plan to outline the proof
of the fact that in the Sacks model every Menger totally imperfect set of
reals has size at most w_1.
This is a joint work with V. Haberl and P. Szewczak.
Time and Place
Talk at 11:30am in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk to
vera.fischer@univie.ac.at.
Wednesday seminar -- joint seminar of the MLTCS department
Prague Set Theory Seminar
4/20/2023 8:54:54
Dear all,
The seminar next week will be held as a joint seminar of the MLTCS
department. This means we expect a slightly wider audience and the plan
is to go for a lunch after the seminar. Please do let me know if you
intend to come so that we can make estimates for the table reservation.
***ROOM CHANGE***
The seminar will meet on Wednesday April 26th at 11:00 in the Institute
of Mathematics CAS, blue lecture hall, ground floor, rear building,
Zitna 25.
Program: David Uhrik -- Colorings of Infinite Graphs
We will give an overview of new results on uncountable graphs obtained
in my phd thesis. Topics will range from Ramsey theory, the chromatic
number to the uncountable Hadwiger conjecture. We studied various graph
constructions in Cohen extensions. We showed that adding aleph-two
Cohen reals forces a weak bipartite-type partition relation on
aleph-two. From a single Cohen real we constructed a triangle free
Hajnal--Máté graph, answering a question of Dániel Soukup. Using the
same method a new construction of a T-Hajnal--Máté graph was provided in
ZFC. We introduced so-called delta-Hajnal--Máté graphs and showed that
they do not exist under Martin's axiom. Lastly in connection to the
uncountable Hadwiger conjecture we proved that the least size of a
counterexample to the uncountable Hadwiger conjecture is equal to the
special tree number.
Best,
David
Charla de Andrés Uribe en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
4/18/2023 9:43:04
Seminario Colombo Mexicano de Teoría de Conjuntos
Abril 20
4:00 p.m. - 5:00 p.m. (hora de Colombia)
FAM-ligadura: hacia una
teoría general de forcing iterado usando medidas finitamente aditivas.
Andrés F. Uribe
Universidad
Nacional de Colombia
Resumen. En
el año 2000, Shelah logró demostrar que, consistentemente, el número de cubrimiento del ideal de los subconjuntos nulos de los números reales puede tener cofinalidad contable. Para ello, usando random forcing, construyó una iteración de soporte finito con
medidas finitamente aditivas. En esta charla se va a presentar la definición de una nueva noción de ligadura, llamada FAM-ligadura,
que permite generalizar la iteración que Shelah introdujo originalmente y definir una teoría general de forcing iterado usando medidas finitamente aditivas. Además, se va a exponer una nueva constelación del digrama de Cichoń donde se separa el lado izquierdo,
y el número de cubrimiento del ideal de los subconjuntos nulos de los números reales es singular.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
Cross-Alps Logic Seminar (speaker: Márton Elekes)
Cross-Alps Logic Seminar
4/17/2023 13:54:32
On Friday 21.04.2023 at 16.00
Márton Elekes (Rényi Institute and Eötvös Loránd University)
will give a talk on
On various notions of universally Baire sets
Please refer to the usual webpage
of our LogicGroup for more details and the abstract of the talk. The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
All the best,Vincenzo
Nankai Logic Colloquium
Nankai Logic Colloquium
4/17/2023 9:52:16
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Raphael Carroy from the University of Turin. This talk is going to take place this Friday, Apr. 21, from 4pm to 5pm (UTC+8, Beijing time).
Title: Continuous reducibility is a well-quasi-order on continuous functions with Polish 0-dimensional domains.
Abstract: Given topological spaces $X,X',Y,Y'$, and two functions $f:X\to Y$ and $f':X'\to Y'$, we say that $f$ \emph{reduces continuously} to $f'$ when there is a pair $(\sigma,\tau)$ of continuous functions such that $f=\tau\circ f'\circ\sigma$. This quasi-order has first been introduced by Weihrauch in the context of Computable Analysis at the beginning of the 1990s. It has recently received interest in Descriptive Set Theory.
With Yann Pequignot, we proved that on the class of continuous functions with Polish 0-dimensional domains, there are no infinite antichains and no infinite strictly descending chains for continuous reducibility. In other words, continuous reducibility is a well-quasi-order on this class of functions.
I will give some context for this result and outline the proof.
_________________________________________________________
Title : The 25th Nankai Logic Colloquium --Raphael Carroy
Time :16:00pm, Apr. 21, 2023 (Beijing Time)
Zoom Number : 812 8606 8722
Passcode : 165561
Link : https://us02web.zoom.us/j/81286068722?pwd=V3V3NUpKNFgxQldLdEF1TW56WTNXQT09
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
This Week in Logic at CUNY
4/16/2023 22:38:00
This Week in Logic at CUNY:
- - - - Monday, Apr 17, 2023 - - - -
Rutgers Logic Seminar
Monday, April 17, 2pm, Rutgers University, Hill 005
Alejandro Poveda, CMSA Harvard
The Gluing Property
Logic and Metaphysics WorkshopDate: Monday, April 17, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Branden Fitelson (Northeastern).
Title: Probability and logic/meaning: Two approaches
Abstract: In this talk, I will compare and contrast two approaches to the relation between probability and logic/meaning. First, I will examine the Traditional (“Kolmogorovian”) Approach of setting up probability calculi, which presupposes semantic/logical notions and defines conditional probability in terms of unconditional probability. Then, I will discuss the Popperian Approach, which does not presuppose semantic/logical notions, and which takes conditional probability as primitive. Along the way, I will also discuss the prospects (and pitfalls) of adding an Adams-style conditional to various probability calculi.
- - - - Tuesday, Apr 18, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, April 18, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id) Katarzyna W. Kowalik, University of Warsaw
The chain-antichain principle and proof size
The chain-antichain principle CAC is a well-known consequence of Ramsey's theorem for pairs and two colours RT22. It says that for every partial order on N there exists an infinite chain or antichain with respect to this order. Both of these principles are Π03-conservative over the weak base theory RCA∗0. Such conservation results usually prompt to ask about lengths of proofs. Kołodziejczyk, Wong and Yokoyama proved that RT22 has a non-elementary speedup over RCA∗0 for proofs of Σ1 sentences. We show that the behaviour of CAC is the opposite: it can be polynomially simulated by RCA∗0 with respect to Π03 sentences. Our argument uses a technique of forcing interpretation developed by Avigad. In the first step we syntactically simulate a construction of a generic computable ultrapower of a model of RCA∗0. Then we find a generic cut satisfying CAC inside the ultrapower.
- - - - Wednesday, Apr 19, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Walter Tholen, York University.
Date and Time: Wednesday April 19, 2023, 7:00 - 8:30 PM. ZOOM TALK.
Title: What does “smallness” mean in categories of topological spaces?
Abstract: Quillen’s notion of small object and the Gabriel-Ulmer notion of finitely presentable or generated object are fundamental in homotopy theory and categorical algebra. Do these notions always lead to rather uninteresting classes of objects in categories of topological spaces, such as the class of finite discrete spaces, or just the empty space , as the examples and remarks in the existing literature may suggest?
In this talk we will demonstrate that the establishment of full characterizations of these notions (and some natural variations thereof) in many familiar categories of spaces, such as those of T_i-spaces (i= 0, 1, 2), can be quite challenging and may lead to unexpected surprises. In fact, we will show that there are significant differences in this regard even amongst the categories defined by the standard separation conditions, with the T1-separation condition standing out. The findings about these specific categories lead us to insights also when considering rather arbitrary full reflective subcategories of Top.
(Based on joint work with J. Adamek, M. Husek, and J. Rosicky.)
- - - - Thursday, Apr 20, 2023 - - - -
- - - - Friday, Apr 21, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, April 21, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Mohammad Golshani, Institute for Research in Fundamental Sciences
The proper forcing axiom for ℵ1-sized posets and the continuum
We discuss Shelah's memory iteration technique and use it to show that the PFA for posets of size ℵ1 is consistent with large continuum. This is joint work with David Aspero.
Logic Workshop
CUNY Graduate Center
Friday April 21, 2:00pm-3:30pm, Room 6417
How bad could it be? The semilattice of definable sets in continuous logic
Continuous first-order logic is a generalization of discrete first-order logic suited for studying structures with natural underlying metrics, such as operator algebras and R-trees. While many things from discrete model theory generalize directly to continuous model theory, there are also new subtleties, such as the correct notion of 'definability' for subsets of a structure. Definable sets are conventionally taken to be those that admit relative quantification in an appropriate sense. An easy argument then establishes that the union of definable sets is definable, but in general the intersection of definable sets may fail to be. This raises the question of which semilattices arise as the partial order of definable sets in a continuous theory.
After giving an overview of the basic properties of definable sets in continuous logic, we will give a largely visual proof that any finite semilattice (and therefore any finite lattice) is the partial order of definable sets in some superstable continuous first-order theory. We will then discuss a partial extension of this to certain infinite semilattices.
Next Week in Logic at CUNY:
- - - - Monday, Apr 24, 2023 - - - -
Rutgers Logic Seminar
Monday, April 24, 2pm, Rutgers University, Hill 005
Aristotelis Panagiotopoulos, CMU
Logic and Metaphysics WorkshopDate: Monday, April 24, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/Andrea Iacona (Turin).
Title: Inferentialism and connexivity
Abstract: In my talk I will investigate the relationships between two claims about conditionals that by and large are discussed separately. One is the claim that a conditional holds when its consequent can be inferred from its antecedent, or when the latter provides a reason for accepting the former. The other is the claim that conditionals intuitively obey some characteristic connexive principles, such as Aristotle’s Thesis and Boethius Thesis. Following a line of thought that goes back to Chrysippus, I will suggest that these two claims may coherently be understood as distinct manifestations of a single basic idea, namely, that a conditional holds when its antecedent is incompatible with the negation of its consequent. The account of conditionals that I will outline is based precisely on this idea.
- - - - Tuesday, Apr 25, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, April 25, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Mateusz Łełyk University of Warsaw
- - - - Wednesday, Apr 26, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Dusko Pavlovic, University of Hawai‘i at Mānoa.
Date and Time: Wednesday April 26, 2023, 7:00 - 8:30 PM. ZOOM TALK.
Title: Program-closed categories.
Abstract: > Let CC be a symmetric monoidal category with a comonoid on every object. Let CC* be the cartesian subcategory with the same objects and just the comonoid homomorphisms. A *programming language* is a well-ordered object P with a *program closure*: a family of X-natural surjections
CC(XA,B) <<--run_X-- CC*(X,P)
one for every pair A,B. In this talk, I will sketch a proof that program closure is a property: Any two programming languages are isomorphic along run-preserving morphisms. The result counters Kleene's interpretation of the Church-Turing Thesis, which has been formalized categorically as the suggestion that computability is a structure, like a group presentation, and not a property, like completeness. We prove that it is like completeness. The draft of a book on categorical computability is available from the web site dusko.org.
- - - - Thursday, Apr 27, 2023 - - - -
- - - - Friday, Apr 28, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, April 28, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Will Boney Texas State University
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
Wednesday seminar
Prague Set Theory Seminar
4/16/2023 12:35:02
Dear all,
The seminar meets on Wednesday April 19th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
The program is not yet fixed, the preliminary plan is to look at some
classical forcing results to broaden/refresh our education in the subject.
Best,
David
(KGRC) two talks on Thursday, April 20
Kurt Godel Research Center
4/13/2023 11:40:41
The KGRC welcomes as guests:
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from
April 16 to April 30 and gives a talk, details to be announced at a later
time.
Zoltán Vidnyánszky (host: Vera Fischer) visits the KGRC on April 20 and
gives a talk, see below.
Heike Mildenberger (host: Vera Fischer) visits the KGRC from May 3 to May
6 and gives a talk on May 4, details to be announced at a later time.
Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and
gives a short talk, details to be announced at a later time.
Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June
24 and gives a talk, details to be announced at a later time.
Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23
and gives a talk, details to be announced at a later time.
* * *
For a video recording of Martin Pinsker's talk, please see
his slides at https://dmg.tuwien.ac.at/pinsker/talks/2023/pinsker_KGRC.pdf
and a video recording at
https://univienna.zoom.us/rec/share/rKNNyLly9EuERJbt_r2qp-71ktMjeAR5i5zFIq7HhA0g57kgC_T9tZs4VjMFJc85.fFpWWl1LZ8WHgVGg
(use passcode ?yG874^^ to watch)
* * *
Set Theory Seminar
Kurt Gödel Research Center
Thursday, April 20
(Please note the unuasual day and time: Starting in April, most of the
talks in the Set Theory Seminar will be moved to Thursday, 11:30am. A few
will remain on Tuesday, 3:00pm however.)
"Menger spaces everywhere"
Lyubomyr Zdomskyy (TU Wien)
Combinatorial covering properties, which arose from the study of classical
special sets of reals, appear in many contexts in topology and set theory.
In this talk we shall discuss some applications of the Menger property and
certain stronger versions thereof. It is planned to be a gentle
introduction to the next talk on April 27.
Time and Place
Talk at 11:30am in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk and the Zoom session to
vera.fischer@univie.ac.at.
* * *
Logic Colloquium
Kurt Gödel Research Center
Tuesday, April 20
"Homomorphism problems in the infinite context"
Zoltán Vidnyánszky (Eötvös Loránd U, HU)
The CSP dichotomy of Bulatov and Zhuk is a celebrated theorem of computer
science: it states that given a finite structure H, deciding whether a
structure G admits a homomorphism to G is either easy (in P) or hard
(NP-complete). We will discuss two infinitary versions of this theorem.
First, following Thornton, in the Borel con ext. Here a striking
difference from the finite world emerges: we will show that solving linear
equations over a finite field is already hard ($\Sigma^1_2$-complete).
Second, assuming only ZF, we will consider the relationship of the
H-compactness properties, that is, the statement that for every G if every
finite substructure of G admits a homomorphism to H then so is G. Here we
show that there exists a model M of ZF, such that M $\models$
H-compactness iff the H-homomorphism problem is easy.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
2nd floor
room HS 11
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
Please direct any other questions about this talk and the Zoom session to
vera.fischer@univie.ac.at.
Fwd: Announcement - PhDs in Logic
Barcelona Logic Seminar
4/12/2023 10:17:47
Dear colleagues,
We would like to announce the XIV edition of the conference PhDs in Logic 2023 that will take place in Granada, Spain, 4-6 october.
There will be 6 keynote talks primarily aimed at PhD students and early career researchers.
Keynote speakers:
- Tomás Ibarlucía - Université de Paris
- Nina Gierasimczuk - Danish Technical University
- Amanda Vidal - IIIA - CSIC
- Julian Murzy - University of Salzburg
- María José Frápolli Sanz - Universidad de Granada
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
All participants are encouraged to submit an abstract (1000 words). In case it is accepted, the scientific committee will then decide if the abstract merits a 20 minutes presentation and the poster session, or just the poster session.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Student members of the Association for Symbolic Logic (ASL) may apply for travel support at ASL. Note that such applications have to be submitted at least 3 months prior to the meeting.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Jose Santiago
Daira Pinto
Juan M Santiago
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Charla de Luis Reyes en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
4/11/2023 7:51:54
Seminario Colombo Mexicano de Teoría de Conjuntos
Abril 13
4:00 p.m. - 5:00 p.m. (hora de Colombia)
Espacios
de Johnson-Lindenstrauss y familias AD
Luis D. Reyes
Universidad Nacional Autónoma
de México
Resumen. Los
espacios de Johnson-Lindentrauss fueron introducidos por ambos autores en los años setentas como un contraejemplo 'artificial' a propiedades topológicas en análisis funcional. Sin embargo, el estudio de estos espacios ha llevado a entenderlos a través de familias
casi ajenas (AD) y las compactaciones de su psi-espacio.
En
esta charla, daremos un breve repaso de algunos resultados en esta línea de investigación, así como una introducción a los métodos que permiten traducir propiedades combinatorias de las familias AD a importantes propiedades topológicas de los espacios de Banach.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
Logic Seminar 12 April 2023 17:00 hrs at NUS by Daniel Hoffmann via Zoom
NUS Logic Seminar
4/10/2023 23:10:51
Hello, here is some local talk at 16:00 hrs in which some of the
local people might be interested. In order to avoid a clash, we
start this talk at 17:15 hrs. Chieu Minh, please inform Daniel.
Regards, Frank
On Mon, Apr 10, 2023 at 04:05:19PM +0800, Frank STEPHAN wrote:
> Invitation to the Logic Seminar at the National University of Singapore
>
> Date: Wednesday, 12 April 2023, 17:00 hrs
>
> Place: Talk via Zoom:
> https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
> Meeting ID: 830 4925 8042
> Passcode: 1729=x3+y3
>
> Speaker: Daniel Hoffmann
>
> Title: Model completeness of SL(2,R)
>
> URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
>
> I will present some results from my joint project with Chieu Minh
> Tran and Jinhe Ye. Model completeness is a weakening of quantifier
> elimination. The main task here is to define a field in the structure
> of the pure group, but in such a way that this definition transfers
> over some group extensions. I will recall basic facts from the model
> theory needed here and similar recent results in the field, then -
> hopefully - I will be able to sketch the idea of the proof, which is
> quite geometric.
>
This Week in Logic at CUNY
This Week in Logic at CUNY
4/10/2023 11:44:34
This Week in Logic at CUNY:
- - - - Monday, Apr 10, 2023 - - - -
Rutgers Logic Seminar - TODAY'S SEMINAR CANCELLED
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***
- - - - Tuesday, Apr 11, 2023 - - - -
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***- - - - Wednesday, Apr 12, 2023 - - - -
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***- - - - Thursday, Apr 13, 2023 - - - -
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***
- - - - Friday, Apr 14, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, April 14, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Gabriel Goldberg, University of California, Berkeley
TBA
Next Week in Logic at CUNY:
- - - - Monday, Apr 17, 2023 - - - -
Rutgers Logic Seminar
Monday, April 17, 2pm, Rutgers University, Hill 005
Alejandro Poveda, CMSA Harvard
Logic and Metaphysics WorkshopDate: Monday, April 17, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Branden Fitelson (Northeastern).
Title: Probability and logic/meaning: Two approaches
Abstract: In this talk, I will compare and contrast two approaches to the relation between probability and logic/meaning. First, I will examine the Traditional (“Kolmogorovian”) Approach of setting up probability calculi, which presupposes semantic/logical notions and defines conditional probability in terms of unconditional probability. Then, I will discuss the Popperian Approach, which does not presuppose semantic/logical notions, and which takes conditional probability as primitive. Along the way, I will also discuss the prospects (and pitfalls) of adding an Adams-style conditional to various probability calculi.
- - - - Tuesday, Apr 18, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, April 18, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id) Katarzyna W. Kowalik, University of Warsaw
- - - - Wednesday, Apr 19, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Walter Tholen, York University.
Date and Time: Wednesday April 19, 2023, 7:00 - 8:30 PM. ZOOM TALK.
Title: What does “smallness” mean in categories of topological spaces?
Abstract: Quillen’s notion of small object and the Gabriel-Ulmer notion of finitely presentable or generated object are fundamental in homotopy theory and categorical algebra. Do these notions always lead to rather uninteresting classes of objects in categories of topological spaces, such as the class of finite discrete spaces, or just the empty space , as the examples and remarks in the existing literature may suggest?
In this talk we will demonstrate that the establishment of full characterizations of these notions (and some natural variations thereof) in many familiar categories of spaces, such as those of T_i-spaces (i= 0, 1, 2), can be quite challenging and may lead to unexpected surprises. In fact, we will show that there are significant differences in this regard even amongst the categories defined by the standard separation conditions, with the T1-separation condition standing out. The findings about these specific categories lead us to insights also when considering rather arbitrary full reflective subcategories of Top.
(Based on joint work with J. Adamek, M. Husek, and J. Rosicky.)
- - - - Thursday, Apr 20, 2023 - - - -
- - - - Friday, Apr 21, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, April 14, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Mohammad Golshani, Institute for Research in Fundamental Sciences
TBA
Logic Workshop
CUNY Graduate Center
Friday April 21, 2:00pm-3:30pm, Room 6417
James Hanson, University of Maryland
TBA
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email jreitz@citytech.cuny.edu.
Nankai Logic Colloquium
Nankai Logic Colloquium
4/10/2023 9:36:15
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
Our speaker this week will be Chris Laskowski from the University of Maryland. This talk is going to take place this Friday, Apr. 14, from 9am to 10am(UTC+8, Beijing time).
Title: On the Borel complexity of modules
Abstract: We prove that among all countable, commutative rings R (with unit) the theory of R-modules is not Borel complete if and only if there are only countably many non-isomorphic countable R-modules. From the proof, we obtain a succinct proof that the class of torsion free abelian groups is Borel complete.
The results above follow from some general machinery that we expect to have applications in other algebraic settings. Here, we also show that for an arbitrary countable ring R, the class of left R-modules equipped with an endomorphism is Borel complete; as is the class of left R-modules equipped with predicates for four submodules. This is joint work with Danielle Ulrich.
_________________________________________________________
Title : The 24th Nankai Logic Colloquium --Chris Laskowski
Time : 9:00am, Apr. 14, 2023 (Beijing Time)
Zoom Number : 836 6352 7223
Passcode : 673161
_____________________________________________________________________
Best wishes,
Ming Xiao
Logic Seminar 12 April 2023 17:00 hrs at NUS by Daniel Hoffmann via Zoom
NUS Logic Seminar
4/10/2023 4:05:19
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 12 April 2023, 17:00 hrs
Place: Talk via Zoom:
https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
Meeting ID: 830 4925 8042
Passcode: 1729=x3+y3
Speaker: Daniel Hoffmann
Title: Model completeness of SL(2,R)
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
I will present some results from my joint project with Chieu Minh
Tran and Jinhe Ye. Model completeness is a weakening of quantifier
elimination. The main task here is to define a field in the structure
of the pure group, but in such a way that this definition transfers
over some group extensions. I will recall basic facts from the model
theory needed here and similar recent results in the field, then -
hopefully - I will be able to sketch the idea of the proof, which is
quite geometric.
Wednesday seminar
Prague Set Theory Seminar
4/8/2023 8:03:55
Dear all,
The seminar meets on Wednesday April 12th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Martin Balko -- On ordered Ramsey numbers
The ordered Ramsey number of an ordered graph G^< (that is, graph with a
fixed linear ordering of its vertices) is the smallest positive integer
N such that every 2-coloring of the edges of ordered K^
Nankai Logic Colloquium
Nankai Logic Colloquium
4/3/2023 11:02:54
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be David Schritesser from Harbin Institute of Technology. This talk is going to take place this Friday, Apr 07 , from 4pm to 5pm(UTC+8, Beijing time).
Title: Definability of Maximal Cofinitary Groups
Abstract: The notion of a cofinitary groups was named by Peter Cameron in the 1980ies, as a dual to the notion of finitary permutation groups. Cameron asked about such groups which are maximal in the sense that they are not proper subgroups of another cofinitary group. It was long thought that such maximal cofinitary groups are necessarily extremely complicated objects.
In 2016, Horowitz and Shelah showed that there is a Borel maximal cofinitary group. I recent joint work with my student Severin Mejak, that there is even an F_sigma such group, which is isomorphic to a free group. Among free maximal cofinitary groups, this is the lowest possible complexity. In this talk, I will give some ideas of the proof.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 23rd Nankai Logic Colloquium --David Schrittesser
Time : 16:00pm, Apr. 07, 2023 (Beijing Time)
Zoom Number : 867 3454 6492
Passcode : 766848
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
This Week in Logic at CUNY
4/2/2023 21:29:22
This Week in Logic at CUNY:
- - - - Monday, Apr 3, 2023 - - - -
Logic and Metaphysics WorkshopDate: Monday, April 3, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Thomas Ferguson (Czech Academy of Sciences).
Title: Care-theoretic semantics: Problems and non-deterministic solutions
Abstract: In this talk I will present the details of a project of care-theoretic semantics in which a linguistic feature of care–rather than truth–is understood as the fundamental semantic property. I will review the details, including how adopting a bounds consequence position in which bounds are determined by considerations of topic allows one to determine both a theory of inference and theory of meaning on the basis of care alone. I will consider two challenges to the project: that of the reconciliation of topic-theoretic and truth-theoretic bounds (in which we need to acknowledge cases in which a position crosses both types of bounds) and sui generis monstrous content (in which two anodyne sentences together yield a content-theoretic violation). I will show that in both cases intuitions suggest the use of Nmatrices in the style of Avron and consider the merits of their employment in the care-theoretic setting.
- - - - Tuesday, Apr 4, 2023 - - - -
- - - - Wednesday, Apr 5, 2023 - - - -
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***
- - - - Thursday, Apr 6, 2023 - - - -
- - - - Friday, Apr 7, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, April 7, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Miha Habič, Bard College at Simon's Rock
Some old and new results on nonamalgamable forcing extensions
Fixing some countable transitive model M of set theory, we can consider its generic multiverse, the family of all models obtainable from M by taking any sequence of forcing extensions and ground models. There is an attractive similarity between the generic multiverse and the Turing degrees, but the multiverse has the drawback (or feature?) that it contains nonamalgamable models, that is, models with no common upper bound, as was observed by several people, going back to at least Mostowski. In joint work with Hamkins, Klausner, Verner, and Williams in 2019, we studied the order-theoretic properties of the generic multiverse and, among other results, gave a characterization of which partial orders embed nicely into the multiverse. I will present our results in the simplest case of Cohen forcing, as well as existing generalizations to wide forcing, and some new results on non-Cohen ccc forcings.
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***
Next Week in Logic at CUNY:
- - - - Monday, Apr 10, 2023 - - - -
Rutgers Logic Seminar
Monday, April 10, 2pm, Rutgers University, Hill 005
Victoria Gitman, CUNY
Jensen's forcing at an inaccessible
- - - - Tuesday, Apr 11, 2023 - - - -
- - - - Wednesday, Apr 12, 2023 - - - -
- - - - Thursday, Apr 13, 2023 - - - -
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***
- - - - Friday, Apr 14, 2023 - - - -
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to Jonas.Reitz12@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email Jonas.Reitz12@citytech.cuny.edu.
Wednesday seminar
Prague Set Theory Seminar
4/2/2023 14:15:16
Dear all,
The seminar meets on Wednesday April 5th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Jonathan Cancino Manriquez -- On AD families of subsets of the
rational numbers
We will talk about some basic properties of almost disjoint families
modulo the ideal of nowhere dense sets.
Best,
David
Logic Seminar 5 April 2023 17:00 hrs at NUS by Frank Stephan
NUS Logic Seminar
4/1/2023 18:04:44
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 5 April 2023, 17:00 hrs
Place: NUS, Department of Mathematics, S17#05-11
Speaker: Frank Stephan
Title: Languages given by finite automata over the unary alphabet
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Languages over the unary alphabet have been studied in computer
science for a long time. The present work investigates regular
languages over the unary alphabet and one investigates the various
forms of representing them by finite automata. Here three types
of automata are studied:
(a) Deterministic finite automata where the finite automaton has
exactly one run per word which is accepting iff the word is in
the given language.
(b) Nondeterministic finite automata where there are choices in
the states on how to procede with a run on various symbols, a
word is in the language iff there is some run which is accepting.
(c) Unambiguous finite automata which are a special case of
nondeterministic finite automata and which either reject a
word or which have exactly one accepting run for a word.
The results presented are from the following two areas:
(1) This paper improves the upper bound of the equality problem
of unary nondeterministic automata from an exponential in the
second root to an exponential in the third root of the number
of states. This almost matches a known lower bound based on
the exponential time hypothesis by Fernau and Krebs.
(2) It is established that the standard regular operations
of union, intersection, complementation and Kleene star cause
either only a polynomial or a quasipolynomial blow-up.
Concatenation of two n-state ufas, in worst case, causes
a blow-up from n to a function with an exponent of sixth
root of n. Decision problems of finite formulas using regular
operations and comparing languages given by n-state unambiguous
automata, in worst case, require an exponential-type of time
under the Exponential Time hypothesis and this complexity goes
down to quasipolynomial time in the case that the concatenation
of languages is not used in the formula. Merely comparing two
languages given by n-state ufas in Chrobak Normal Form is in LOGSPACE.
This talk is joint work with Gordon Hoi, Sanjay Jain and
Christopher Tan.
Core Model Seminar next Tuesday
Carnegie Mellon Logic Seminar
3/29/2023 8:46:32
TUESDAY, April 4, 2023
Core Model Seminar: 1:30 - 3 PM Eastern,
Online, Martin Zeman, University of California, Irvine
Join Zoom Meeting:
https://cmu.zoom.us/j/97749733438?pwd=Yk5PcSsvekptWWxMNUhCU2pFbzA0Zz09Meeting ID: 977 4973 3438
Passcode: 457791
TITLE: Distributivity of iterated club shooting and fine structural
models, part 1
ABSTRACT: Iterative adding closed unbounded sets through stationary sets found quite a few applications in set theory. One natural way to do this is adding club sets using posets consisting of initial segments of the desired clubs. In such situations, one important property of such iterations is sufficient amount of distributivity. In fact, establishing distributivity is often the main part of arguments that involve iterated club shooting.
There are two possible situations where one iteratively adds clubs.
First, for a fixed cardinal $\kappa$, one iteratively adds club subsets
of $\kappa^+$. This kind of construction proved to have many applications. Second, one may start with a cardinal $\delta$ and
iteratively add club subsets of cardinals $\kappa^+$ where $\kappa$
ranges over some set above $\delta$. Surprisingly, this kind of construction has not been much studied. In this talk we will focus on this situation.
In order to add a club subset of some stationary set $S$ the set $S$
must be large in a certain sense; such sets are called fat. It is known
that, consistently, iteratively adding club subsets of fat stationary sets
of $\omega_n$ on a tail-end of $n\in\omega$ followed by forming an
inverse limit at the end may collapse $\aleph_n$ to $\omega$. A strong form of fatness is the property of being the complement of a
non-reflecting stationary set. One can prove, using a fairly standard
argument, that if the iteration described above uses complements of
non-reflecting stationary sets instead of just fat sets, then such an
iteration is $(\omega_{n+1},\infty)$-distributive where $\omega_n$ is
the first active step in the iteration. One can also prove in ZFC that
the analogous amount of distributivity holds of longer iterations,
where the first active step is at $\delta$ and inverse limits are used
at singular steps, as long as the singular steps are of cofinality
$<\delta$. Passing through singular steps of cofinality $\ge\delta$
seems to be difficult, and we only know how to do this over a fine
structural model where the non-reflecting stationary sets are carefully
chosen. Even in such a seemingly special case, the method does have applications.
This is a part of a joint work of Foreman-Magidor-Zeman on games with filters.
Charla de Daniel Calderón en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
3/27/2023 12:19:39
Seminario Colombo Mexicano de Teoría de Conjuntos
Marzo 30
4:00 p.m. - 5:00 p.m. (hora de Colombia)
La conjetura de Borel y conjuntos magro-aditivos
Daniel Calderón
Universidad de Toronto
Resumen. Los
conjuntos fuertemente nulos fueron introducidos por Borel y han sido estudiados desde comienzos del siglo pasado. Borel conjeturó
que todo conjunto fuertemente nulo de reales debe ser contable. Algunos años más tarde, Sierpiński
demostró que asumiendo CH existe un conjunto fuertemente nulo no contable. Sin embargo, la pregunta por la consistencia relativa
a ZFC de la conjetura de Borel siguió irresoluta hasta que en 1976 Laver construyó, en un
trabajo innovador, un modelo de ZFC en el que todo conjunto fuertemente nulo de reales es contable.
Un resultado debido a Galvin, Mycielski y Solovay, provee una caracterización
de nulidad fuerte en términos de una propiedad algebraica para subconjuntos de la recta real. Utilizando esta caracterización,
la noción de magro-aditividad apareció en escena. La magro-aditividad, al igual que otras nociones
de pequeñes en la recta real, han recibido especial atención en años recientes. Una pregunta de 1993, debida a Bartoszyński y Judah,
cuestiona si los conjuntos fuertemente nulos y los conjuntos magro-aditivos tienen una muy
rígida relación en el sentido siguiente:
Pregunta (Bartoszyński–Judah, 1993):
¿Si todo subconjunto fuertemente nulo de la recta real es magro-aditivo, necesariamente vale la conjetura de
Borel?
En esta charla daré algunos detalles sobre la consistencia relativa
de una respuesta negativa a la pregunta de Bartoszyński y Judah, construyendo un modelo
de ZFC en el que todo conjunto fuertemente nulo de reales es magro-aditivo y la conjetura de Borel falla.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
Nankai Logic Colloquium
Nankai Logic Colloquium
3/27/2023 11:47:29
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Samuel Coskey from Boise State University. This talk is going to take place this Friday, Mar 31, from 16:00 to 17:00(UTC+8, Beijing time).
Title: Borel classification of conjugacy problems
Abstract: We aim to study the complexity of conjugacy problems for automorphisms of countable graphs G. Since conjugacy is an equivalence relation on Aut(G), we will study complexity using the invariant descriptive set theory, that is, the Borel reducibility hierarchy. After introducing this background setup, we will give a series of examples of locally finite graphs G whose conjugacy problems have a variety of different complexities. We will see conjugacy problems which are smooth (completely classifiable), complete for hyperfinite relations (E0), complete for essentially countable Borel equivalence relations (E_infinity), and intermediate between E0 and E_infinity.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 22nd Nankai Logic Colloquium --Samuel Coskey
Time : 16:00pm, Mar. 31, 2023 (Beijing Time)
Zoom Number : 830 5925 5547
Passcode : 890764
Link : https://us02web.zoom.us/j/83059255547?pwd=V29IcGo0bWdyeitRdHc5eUhBSnNrQT09
_____________________________________________________________________
Best wishes,
Ming Xiao
Cross-Alps Logic Seminar (speaker: Ludovic Patey)
Cross-Alps Logic Seminar
3/27/2023 6:55:25
On Friday 31.03.2023 at 16.00
Ludovic Patey (CNRS)
will give a talk on
Canonical notions of forcing in Reverse Mathematics
Please refer to the usual webpage
of our LogicGroup for more details and the abstract of the talk. The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
All the best,Vincenzo
Logic Seminar Wednesday 29 March 2023 17:00 hrs at NUS by Xie Ruofei
NUS Logic Seminar
3/27/2023 4:33:42
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 29 March 2023, 17:00 hrs
Place: NUS, Department of Mathematics, S17#05-11
Talk via Zoom:
https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
Meeting ID: 830 4925 8042
Passcode: 1729=x3+y3
Speaker: Xie Ruofei
Title: Majorising the Optimal C.E. Supermartingale
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
In the article "Highness Properties Close to PA-Completeness", Greenberg,
Miller and Nies left the following questions:
(1) Is there a finite collection of functionals {Gamma_i:i
This Week in Logic at CUNY
This Week in Logic at CUNY
3/26/2023 22:31:00
This Week in Logic at CUNY:
- - - - Monday, Mar 27, 2023 - - - -
Logic and Metaphysics WorkshopDate: Monday, March 27, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Gregory Taylor (CUNY)
Title: First-order logics over fixed domain
Abstract: What we call first-order logic over fixed domain was initiated, in a certain guise, by Peirce around 1885 and championed, albeit in idiosyncratic form, by Zermelo in papers from the 1930s. We characterize such logics model- and proof-theoretically and argue that they constitute exploration of a clearly circumscribed conception of domain-dependent generality. Whereas a logic, or family of such, can be of interest for any of a variety of reasons, we suggest that one of those reasons might be that said logic fosters some clarification regarding just what qualifies as a logical concept, a logical operation, or a logical law.
- - - - Tuesday, Mar 28, 2023 - - - -
- - - - Wednesday, Mar 29, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Jim Otto.
Date and Time: Wednesday March 29, 2023, 7:00 - 8:30 PM. ZOOM TALK
Title: P Time, A Bounded Numeric Arrow Category, and Entailments.
Abstract: We revisit the characterization of the P Time functions from our McGill thesis.
1. We build on work of L. Roman (89) on primitive recursion and of A. Cobham (65) and Bellantoni-Cook(92) on P Time.
2. We use base 2 numbers with the digits 1 & 2. Let N be the set of these numbers. We split the tapes of a multi-tape Turing machine each into 2 stacks of digits 1 & 2. These are (modulo allowing an odd numberof stacks) the multi-stack machines we use to study P Time.
3. Let Num be the category with objects the finite products of N and arrows the functions between these. From its arrow category Num^2 we abstract the doctrine (here a category of small categories with chosen structure) PTime of categories with with finite products, base 2 numbers, 2-comprehensions, flat recursion, & safe recursion. Since PTime is a locally finitely presentable category, it has an initial category I. Our characterization is that the bottom of the image of I in Num^2 consists of the P Time functions.
4. We can use I (thinking of its arrows as programs) to run multi-stack machines long enough to get P Time.This is the completeness of the characterization.
5. We cut down the numeric arrow category Num^2, using Bellantoni-Cook growth & time bounds on the functions, to get a bounded numeric arrow category B. B is in the doctrine PTime. This yields the soundness of the characterization.
6. For example, the doctrine of toposes with base 1 numbers, choice, & precisely 2 truth values (which captures much of ZC set theory) likely lacks an initial category, much as there is an initial ring, but no initial field.
7. On the other hand, the L. Roman doctrine PR of categories with finite products, base 1 numbers, & recursion (that is, product stable natural numbers objects) does have an initial category as it consists of the strong models of a finite set of entailments. And is thus locally finitely presentable. We sketch the signature graph for these entailments. And some of these entailments. Similarly (but with more complexity) there are entaiments for the doctrine PTime.
- - - - Thursday, Mar 30, 2023 - - - -
- - - - Friday, Mar 31, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, March 31, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Benjamin Goodman, CUNY
Σn-correct forcing axioms
The standard method of producing a model of a forcing axiom from a supercompact cardinal in fact gives a model of an even stronger principle: that for every small name a and every Σ2 formula arphi such that φ(a) is forceable by and preserved under further forcing in our forcing class, there is a filter F which meets a desired collection of dense sets and also interprets a such that φ(aF) already holds. I will show how to generalize this result to formulas of higher complexity by starting with slightly stronger large cardinal assumptions, then discuss the bounded versions of these enhanced forcing axioms, their relationships to other similar principles, and their consequences.
Logic Workshop
CUNY Graduate Center
Friday March 31, 2:00pm-3:30pm, Room 6417
Corey Switzer, University of Vienna
Galois-Tukey reductions and canonical structure in the Cichoń diagram
Cardinal invariants of the continuum are cardinal numbers which, roughly, measure how 'badly' CH fails in various mathematical contexts such as analysis and topology. For instance the cardinal add(N) is the least κ for which there are κ many Lebesgue measure zero sets of reals whose union is not measure zero. Classical facts imply ℵ1≤add(N)≤2ℵ0 but the precise value is undetermined in ZFC and depends heavily on the axioms of set theory. Other numbers follow a similar pattern of 'the least size of a set of reals (Borel sets, etc) lacking a classical smallness property'.
The Cichoń diagram displays cardinal invariants related to Lebesgue measure (the null ideal), Baire category (the meager ideal) as well as the bounding and dominating numbers which concern growth rates of functions. Many surprising ZFC-inequalities exist between these cardinals suggesting a rich world living on the reals in various models of set theory. At the combinatorial heart of every proof of a ZFC inequality derives from a Galois-Tukey reduction: the (ZFC-provable) existence of a pair of continuous maps with simple properties that make sense outside of the context of logic and indeed would be sensible to any analyst or topologist.
In this talk we will discuss some recent work in progress on the descriptive complexity of maps witnessing consistent but non-provable implications. We will show using largely computability theoretic methods that in Gödel's constructible universe there are low level projective reductions between any two cardinal invariants - thus CH holds in a very 'definable' way, while in Solovay's model of 'all sets of reals are Lebesgue measurable' (and therefore the axiom of choice fails) there are no non-ZFC provable implications thus these cardinals are all as different as possible.
Next Week in Logic at CUNY:
- - - - Monday, Apr 3, 2023 - - - -
Logic and Metaphysics WorkshopDate: Monday, April 3, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/Thomas Ferguson (Czech Academy of Sciences).
Title: Care-theoretic semantics: Problems and non-deterministic solutions
Abstract: In this talk I will present the details of a project of care-theoretic semantics in which a linguistic feature of care–rather than truth–is understood as the fundamental semantic property. I will review the details, including how adopting a bounds consequence position in which bounds are determined by considerations of topic allows one to determine both a theory of inference and theory of meaning on the basis of care alone. I will consider two challenges to the project: that of the reconciliation of topic-theoretic and truth-theoretic bounds (in which we need to acknowledge cases in which a position crosses both types of bounds) and sui generis monstrous content (in which two anodyne sentences together yield a content-theoretic violation). I will show that in both cases intuitions suggest the use of Nmatrices in the style of Avron and consider the merits of their employment in the care-theoretic setting.
- - - - Tuesday, Apr 4, 2023 - - - -
- - - - Wednesday, Apr 5, 2023 - - - -
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***
- - - - Thursday, Apr 6, 2023 - - - -
- - - - Friday, Apr 7, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, April 7, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Miha Habič, Bard College at Simon's Rock
*** April 5-13, 2023 Spring Recess CUNY Graduate Center ***
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to Jonas.Reitz12@citytech.cuny.edu.If you have a logic-related event that you would like included in future mailings, please email Jonas.Reitz12@citytech.cuny.edu.
Wednesday seminar
Prague Set Theory Seminar
3/24/2023 4:41:58
Dear all,
The seminar meets on Wednesday March 29th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Peter Vojtáš -- Considerations on Galois--Tukey motivated by
complexity theory and reverse mathematics
We will try to walk through the landscape motivated by following
publications
Peter Vojtas. Generalized Galois-Tukey connections between
explicit relations on classical objects of real analysis, IMCP 6 (1993)
619-643
Andreas Blass. Questions and Answers -- A Category Arising in
Linear Logic, Complexity Theory, and Set Theory, LMSLN 222 (1995) 61-81
Damir D. Dzhafarov , Carl Mummert. Reverse Mathematics - Problems,
Reductions, and Proofs, Springer 2022
to perceive different phenomena, hoping to formulate some new
observations and problems Considerations on Galois--Tukey motivated by
complexity theory and reverse mathematics.
Best,
David
(KGRC) guests, video recordings and notes, and four talks
Kurt Godel Research Center
3/23/2023 12:54:24
The KGRC welcomes as guests:
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15.
Franz-Viktor Kuhlmann (host: Matthias Aschenbrenner) visits the KGRC from
March 27 to March 31.
José Nicolás Nájar Salinas (host: Miguel Moreno) visits the KGRC and gives
a talk on March 29, see below.
Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from
April 16 to April 30 and gives a talk, details to be announced at a later
time.
Zoltán Vidnyánszky (host: Vera Fischer) visits the KGRC on April 20 and
gives a talk, details to be announced at a later time.
Fabian Kaak (host: Vera Fischer) visits the KGRC from May 23 to May 26 and
gives a short talk, details to be announced at a later time.
Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June
24 and gives a talk, details to be announced at a later time.
Nadiya Kolos (host: Miguel Moreno) visits the KGRC from June 19 to June 23
and gives a talk, details to be announced at a later time.
* * *
video recordings and slides:
For a video recording of part 1 of Miguel Moreno's tutorial, please use
https://univienna.zoom.us/rec/share/0CoE9CuBiOXjuXf9dMiFnu63mp4xQCYvQSzjDNFeQT9edwtb9hVwDO6PvBXhSUaH.agwwTP4Mj8fEhKRn
and passcode W^9Ej.h3
For part 2, please use
https://univienna.zoom.us/rec/share/ltSirTm_O_ONGvGOu-9yJavOaG9QrihlrRtgWNixtSbZZtFTH4gaN7NliBodw44R.dEi0C8qkgxq__Sxp
and passcode d3P&V1g$
Notes for the series so can be found here (and will also be updated here after
part 3 will be delivered):
https://mathematik.univie.ac.at/fileadmin/user_upload/f_mathematik/Events_News/Vortraege_Events/2023-24/KGRC_Set_Theory_2023-03_Miguel_Moreno.pdf
For a video recording of Silvain Rideau-Kikuchi's talk, please use
https://univienna.zoom.us/rec/share/WZ_GtG4tfySmIRU_O2axDtut8U8bxqNznZvCwk0rFd1nODm43gNH_UNMZUYdmV3j.-1kMmpCZag-qvkL6
and passcode @d1yoKnn
* * *
Set Theory Research Seminar
Kurt Gödel Research Center
Tuesday, March 28
"Generalised Descriptive Set Theory, part III"
Miguel Moreno (KGRC)
During this talk we will discuss where in the generalized
Borel-reducibility hierarchy are the isomorphism relation of first order
complete theories. These theories are divided into two kinds: classifiable
and non-classifiable. To study the classifiable theories case is needed
the use of Ehrenfeucht-Frass games. On the other hand the study of the
non-classifiable theories is done by using colored ordered trees. The goal
of the talk is to see the classifiable theories case and sketch the ideas
of non-classifiable theories.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at!
(Students at Uni Wien are required to attend in person.)
Please direct any other questions about this talk to vera.fischer@univie.ac.at.
* * *
Mathematical Colloquium
Institut für Mathematik
Wednesday, March 29
"Independence Phenomena in Mathematics: Current Obstacles and Scenarios
for Solutions"
Sandra Müller (TU Wien)
The standard axioms of set theory, the Zermelo-Fraenkel axioms (ZFC), do
not suffice to answer all questions in mathematics. While this follows
abstractly from Kurt Gödel's famous incompleteness theorems, we nowadays
know numerous concrete examples for such questions. A large number of
problems in set theory, for example, regularity properties such as
Lebesgue measurability and the Baire property are not decided - for even
rather simple (for example, projective) sets of reals - by ZFC. Even many
problems outside of set theory have been shown to be unsolvable, meaning
neither their truth nor their failure can be proven from ZFC. A major part
of set theory is devoted to attacking this problem by studying various
extensions of ZFC and their properties. I will outline some of these
extensions and explain current obstacles in understanding their impact on
the set theoretical universe together with recent progress on these
questions and future scenarios. This work is related to the overall goal
to identify the "right" axioms for mathematics.
Time and Place
Coffee at 2:45pm
Talk at 3:15pm
Vinum cum Pane following the talk
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
12th floor
Sky Lounge
Please direct any questions about this talk to anton.mellit@univie.ac.at
or jose.luis.romero@univie.ac.at.
* * *
Model Theory Research Seminar
Kurt Gödel Research Center
Wednesday, March 29
"Definability In Abstract Elementary Classes"
José Nicolás Nájar Salinas
(Fundación Universidad América, CO)
The development of definability in the context of Abstract Elementary
Classes has been boosted by the recent work of Shelah and Villaveces in
which they prove that for every AEC $\mathcal{K}$ in a vocabulary $\tau$,
there is a sentence
$\psi\in\mathbb{L}_{\beth_2(\kappa)^{+++},\kappa}(\tau)$ axiomatizing
where $\kappa$ is the Löwenheim-Skolem number of the class. Vasey enlarges
$\tau$ to $\Tilde{\tau}$ and proves that if the AEC is tame and
type-short, there is a bijection between the Galois Types of the AEC and
the quantifier free types in an infinitary logic
$\mathbb{L}_{\lambda,\lambda}(\Tilde{\tau})$ for some suitable $\lambda$,
the semantic-syntactic correspondence. We extend the ideas of Vasey to
make a partial semantic-syntactic correspondence-like results between
Galois types and some types of the logic
$\mathbb{L}_{\beth_2(\kappa)^{+++},\kappa}(\tau)$. Part of this is joint
work with Andrés Villaveces.
Time and Place
Talk at 3:00pm
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Please direct any questions about this talk to
matthias.aschenbrenner@univie.ac.at.
* * *
Logic Colloquium
Kurt Gödel Research Center
Thursday, March 30
"Constraint Satisfaction Problems: algebraic and model-theoretic
challenges to distinguish the easy from the hard"
Michael Pinsker (TU Wien)
I will give a gentle introduction to current algebraic and model-theoretic
methods in the computational complexity of Constraint Satisfaction
Problems (CSPs).
A CSP is a computational problem where we are given variables and
constraints about them; the question is whether the variables can be
assigned values such that all constraints are satisfied. Numerous natural
computational problems, such as satisfiability of a given system of
equations over a field, are CSPs; in fact, any computational problem is
Turing-equivalent to a CSP.
Any CSP can be modeled by a relational structure, and conversely every
relational structure naturally defines a CSP. In view of humanity's
continuing quest to distinguish easy from hard problems in general, and
the class P (polynomial-time solvable problems, e.g. satisfiability of
linear equations over a field) from the class NP (polynomial-time
verifiable problems, e.g. satisfiability of a propositional formula) in
particular, the question arises which mathematical properties of a
relational structure make the corresponding CSP easy and which make it
hard. It turns out that particular algebraic invariants of the structure
often determine the borderline between different complexity classes. Hence
algebraic methods, combined with concepts from model theory as well as
from Ramsey theory in the case of infinite structures, yield appropriate
tools to determine the computational complexity of CSPs.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
2nd floor
room HS 11
Zoom: If you need the Zoom data and have not received the meeting link by the day before the talk, please contact richard.springer@univie.ac.at!
(Students at Uni Wien are required to attend in person.)
Please direct any questions about this talk to
matthias.aschenbrenner@univie.ac.at.
Charla de Slawomir Solecki en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
3/20/2023 11:08:44
Seminario Colombo Mexicano de Teoría de Conjuntos
March 23
4:00 p.m. - 5:00 p.m. (Colombia time)
Descriptive set theory and closed groups generated
by measure preserving transformations
Slawomir Solecki
Cornell University
Abstract. The
talk is about applications of Descriptive Set Theory to Ergodic Theory.
The behavior of a measure preserving transformation,
even a generic one, is highly non-uniform.
In contrast to this observation, a different picture of a very uniform behavior of the closed group generated by a generic measure preserving transformation $T$ has emerged. This picture included substantial evidence that pointed to these groups (for a generic
$T$) being all topologically isomorphic to a single group, namely, $L^0$---the topological group of all Lebesgue measurable functions from $[0,1]$ to the circle. In fact, Glasner
and Weiss asked if this is the case.
We
will describe the background touched on above, including the descriptive set theoretic background. We will indicate a proof of the following theorem that answers the Glasner--Weiss question in the negative: for a generic measure preserving transformation $T$,
the closed group generated by $T$ is not topologically isomorphic to $L^0$.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
Nankai Logic Colloquium
Nankai Logic Colloquium
3/20/2023 11:01:17
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
Our speaker this week will be Christian Rosendal from the University of Maryland. This talk is going to take place this Friday, Mar.24 , from 9am to 10am(UTC+8, Beijing time).
Title: Amenability, optimal transport and cohomology of Banach modules
Abstract: Using tools from the theory of optimal transport, four results concerning isometric actions of amenable topological groups with potentially unbounded orbits are established. Specifically, consider an amenable topological group $G$ with no non-trivial homomorphisms to $\mathbb R$.
If $d$ is a compatible left-invariant metric on $G$, $E\subseteq G$ is a finite subset and $\epsilon>0$, there is a finitely supported probability measure $\beta$ on $G$ so that
$$
\max_{g,h\in E}\, {\sf W}(\beta g, \beta h)<\eps,
$$
where ${\sf W}$ denotes the {\em Wasserstein} or {\em optimal transport} distance between probability measures on the metric space $(G,d)$. When $d$ is the word metric on a finitely generated group $G$, this strengthens a well known theorem of H. Rei\-ter \cite{reiter}. Furthermore, when $G$ is locally compact, $\beta$ may be replaced by an appropriate probability density $f\in L^1(G)$.
Also, when $G\curvearrowright X$ is a continuous isometric action on a metric space, the space of Lipschitz functions on the quotient $X/\!\!/G$ is isometrically isomorphic to a $1$-complemented subspace of the Lipschitz functions on $X$. And finally every continuous affine isometric action of $G$ on a Banach space has a canonical invariant linear subspace.
These results generalise previous theorems due to Schneider--Thom and C\'uth--Doucha.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title : The 21st Nankai Logic Colloquium --Christian Rosendal
Time : 9:00am, Mar. 24, 2023 (Beijing Time)
Zoom Number : 849 1206 9207
Passcode : 929100
Link : https://zoom.us/j/84912069207?pwd=TTBWakY4OE9sdVNuN2dza3IvemY3Zz09 Christia
_____________________________________________________________________
Best wishes,
Ming Xiao
Logic Seminar Wed 22 March 2023 17:00 hrs at NUS by Takayuki Kihara
NUS Logic Seminar
3/20/2023 4:04:33
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 22 March 2023, 17:00 hrs
Place: NUS, Department of Mathematics, S17#05-11
Speaker: Kihara Takayuki
Title: Topos-theoretic aspect of the degrees of unsolvability
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Abstract:
In this talk, we examine the topos-theoretic aspect of the degrees of
(computable) unsolvability. One of the main interpretations of
constructive mathematics is Kleene's realizability interpretation,
which, as is well known, can be relativized by an oracle. In this
sense, an oracle can be a factor that causes a change in a model of
constructive mathematics.
Let us review this observation from another point of view: there is a
topos, called the effective topos, based on Kleene's realizability
interpretation. And relativizing the realizability interpretation to
an oracle yields a subtopos of the effective topos. Thus, the
structure of oracles, i.e., the structure of the degrees of
unsolvability, is expected to be closely related to the structure of
the subtoposes of the effective topos.
In this talk, we give a complete correspondence, in a strict sense,
between the structure of the degrees of unsolvability and the
structure of subtoposes of the effective topos (or its relatives).
This Week in Logic at CUNY
This Week in Logic at CUNY
3/19/2023 22:42:00
This Week in Logic at CUNY:
- - - - Monday, Mar 20, 2023 - - - -Rutgers Logic Seminar
Monday, March 20, 2pm, Rutgers University, Hill 005
Roman Kossak, CUNY
Absolute Undefinability
Logic and Metaphysics WorkshopDate: Monday, March 20th, 4.15-6.15 (NY time), GC Room 9205NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Speaker: Shawn Simpson (Pitt)
Title: Logic and inference in the sender-receiver model
Abstract: The sender-receiver model was developed by David Lewis to tackle the question of the conventionality of meaning. But many people who cared about the conventionality of meaning did so because they thought it was intimately connected to the conventionality of logic. Since Lewis’s work, only a few attempts have been made to say anything about the nature of logic and inference from the perspective of the sender-receiver model. This talk will look at the what’s been said in that regard, by Skyrms and others, and suggest a few general lessons.
- - - - Tuesday, Mar 21, 2023 - - - -Models of Peano Arithmetic (MOPA)Tuesday, March 21, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id) Bartosz Wcisło, University of Gdańsk
Satisfaction classes with the full collection scheme
Satisfaction classes are subsets of models of Peano arithmetic which satisfy Tarski's compositional clauses. Alternatively, we can view satisfaction or truth classes as the extension of a fresh predicate T(x) (the theory in which compositional clauses are viewed as axioms is called CT^-).
It is easy to see that CT^- extended with a full induction scheme is not conservative over PA, since it can prove, for instance, the uniform reflection over arithmetic. By a nontrivial argument of Kotlarski, Krajewski, and Lachlan, the sole compositional axioms of CT^- in fact form a conservative extension of PA. Moreover, in order to obtain non-conservativity it is enough to add induction axioms for the Delta_0 formulae containing the truth predicate.
Answering a question of Kaye, we will show that the theory of compositional truth, CT^- with the full collection scheme is a conservative extension of Peano Arithmetic. Following the initial suggestion of Kaye, we will in fact show that any countable recursively saturated model M of PA has an elementary omega_1-like end extension M' such that M' carries a full satisfaction class.
- - - - Wednesday, Mar 22, 2023 - - - -- - - - Thursday, Mar 23, 2023 - - - -- - - - Friday, Mar 24, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Friday March 24, 2:00pm-3:30pm, Room 6417
Victoria Gitman CUNY
Parameter-free comprehension in second-order arithmetic
Second-order arithmetic has two types of objects: numbers and sets of numbers, which we think of as the reals. The second-order arithmetic framework has been used successfully to investigate what kinds of real numbers need to exist to prove various significant results in analysis. One of the strongest second-order arithmetic axiomatizations is the theory Z2 consisting of the axioms PA (for numbers), the set induction axiom, and comprehension for all second-order formulas with set parameters. How significant is the inclusion of set parameters in the comprehension scheme? Let Z−p2 be like Z2, but where set parameters are not allowed in the comprehension scheme. Harvey Friedman showed that Z2 and Z−p2 are equiconsistent because parameter-free comprehension suffices to build a model's version of the constructible universe L inside the model and the 'constructible' reals satisfy Z2. Kanovei recently showed that models of Z−p2 can be very badly behaved, for example, their sets may not even be closed under complement. Kanovei also showed that there can be nicely behaved models of Z−p2 in which Σ12-comprehension (with set parameters) holds. He constructed his model in a forcing extension by a tree iteration of Sacks forcing. In Kanovei's model, Σ14-comprehension (with set parameters) fails and he asked whether this can be improved to Σ13-comprehension. In this talk, I will show how to construct a model of Σ12-comprehension and Z−p2 in which Σ13-comprehension fails. The model will be constructed in a forcing extension by a tree iteration of Jensen's forcing. Jensen's forcing is a sub-poset of Sacks forcing constructed by Jensen to show that it is consistent to have a non-constructible Π12-definable singleton real (every Σ12-definable set of reals is constructible by Shoenfield's Absoluteness).
Next Week in Logic at CUNY:
- - - - Monday, Mar 27, 2023 - - - -
Logic and Metaphysics WorkshopDate: Monday, March 27, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Gregory Taylor (CUNY)
Title: First-order logics over fixed domain
Abstract: What we call first-order logic over fixed domain was initiated, in a certain guise, by Peirce around 1885 and championed, albeit in idiosyncratic form, by Zermelo in papers from the 1930s. We characterize such logics model- and proof-theoretically and argue that they constitute exploration of a clearly circumscribed conception of domain-dependent generality. Whereas a logic, or family of such, can be of interest for any of a variety of reasons, we suggest that one of those reasons might be that said logic fosters some clarification regarding just what qualifies as a logical concept, a logical operation, or a logical law.
- - - - Tuesday, Mar 28, 2023 - - - -
- - - - Wednesday, Mar 29, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Jim Otto.
Date and Time: Wednesday March 29, 2023, 7:00 - 8:30 PM. ZOOM TALK
Title: P Time, A Bounded Numeric Arrow Category, and Entailments.
Abstract: We revisit the characterization of the P Time functions from our McGill thesis.
1. We build on work of L. Roman (89) on primitive recursion and of A. Cobham (65) and Bellantoni-Cook(92) on P Time.
2. We use base 2 numbers with the digits 1 & 2. Let N be the set of these numbers. We split the tapes of a multi-tape Turing machine each into 2 stacks of digits 1 & 2. These are (modulo allowing an odd numberof stacks) the multi-stack machines we use to study P Time.
3. Let Num be the category with objects the finite products of N and arrows the functions between these. From its arrow category Num^2 we abstract the doctrine (here a category of small categories with chosen structure) PTime of categories with with finite products, base 2 numbers, 2-comprehensions, flat recursion, & safe recursion. Since PTime is a locally finitely presentable category, it has an initial category I. Our characterization is that the bottom of the image of I in Num^2 consists of the P Time functions.
4. We can use I (thinking of its arrows as programs) to run multi-stack machines long enough to get P Time.This is the completeness of the characterization.
5. We cut down the numeric arrow category Num^2, using Bellantoni-Cook growth & time bounds on the functions, to get a bounded numeric arrow category B. B is in the doctrine PTime. This yields the soundness of the characterization.
6. For example, the doctrine of toposes with base 1 numbers, choice, & precisely 2 truth values (which captures much of ZC set theory) likely lacks an initial category, much as there is an initial ring, but no initial field.
7. On the other hand, the L. Roman doctrine PR of categories with finite products, base 1 numbers, & recursion (that is, product stable natural numbers objects) does have an initial category as it consists of the strong models of a finite set of entailments. And is thus locally finitely presentable. We sketch the signature graph for these entailments. And some of these entailments. Similarly (but with more complexity) there are entaiments for the doctrine PTime.
- - - - Thursday, Mar 30, 2023 - - - -
- - - - Friday, Mar 31, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, March 31, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Benjamin Goodman, CUNY
Σn-correct forcing axioms
The standard method of producing a model of a forcing axiom from a supercompact cardinal in fact gives a model of an even stronger principle: that for every small name a and every Σ2 formula arphi such that φ(a) is forceable by and preserved under further forcing in our forcing class, there is a filter F which meets a desired collection of dense sets and also interprets a such that φ(aF) already holds. I will show how to generalize this result to formulas of higher complexity by starting with slightly stronger large cardinal assumptions, then discuss the bounded versions of these enhanced forcing axioms, their relationships to other similar principles, and their consequences.
Logic Workshop
CUNY Graduate Center
Friday March 31, 2:00pm-3:30pm, Room 6417
Corey Switzer, University of Vienna
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org. v
Wednesday seminar
Prague Set Theory Seminar
3/19/2023 16:28:14
Dear all,
The seminar meets on Wednesday March 22nd at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: David Uhrik -- Hajnal--Máté Graphs and Cohen Reals
We will study Hajnal--Máté (HM) graphs. The first construction of an HM
graph was from the diamond+ principle. Since then several other
constructions were provided with additional interesting properties, e.g.
having no triangles. We will survey results about this class of graphs
and provide a construction of a triangle free HM graph in a model after
adding a single Cohen real. Time permitting we will introduce a
generalization, so-called 𝛿-Hajnal--Máté graphs, and prove some of
their basic properties and deduce a weak partition relation on ω_2.
Best,
David
(KGRC) Set Theory Seminar talk and Geometry and Analysis on Groups Seminar talk
Kurt Godel Research Center
3/16/2023 11:53:04
The KGRC welcomes as guests:
Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31.
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Lou van den Dries (host: Matthias Aschenbrenner) visits the KGRC from
March 10 to March 22.
Chieu-Minh Tran (host: Matthias Aschenbrenner) visits the KGRC from March
19 to March 22 and gives a talk on March 21, see below.
Franz-Viktor Kuhlmann (host: Matthias Aschenbrenner) visits the KGRC from
March 27 to March 31.
José Nicolás Nájar Salinas (host: Miguel Moreno) visits the KGRC and gives
a talk on March 29, details to be announced at a later time.
Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from
April 16 to April 30 and gives a talk, details to be announced at a later
time.
Zoltán Vidnyánszky (host: Vera Fischer) visits the KGRC on April 20 and
gives a talk, details to be announced at a later time.
Jaroslav Šupina (host: Vera Fischer) visits the KGRC from June 18 to June
24 and gives a talk, details to be announced at a later time.
* * *
Set Theory Research Seminar
Kurt Gödel Research Center
Tuesday, March 21
"Generalised Descriptive Set Theory, part II"
Miguel Moreno (KGRC)
We have introduced the notions of K-Borel class, K-analytic class,
K-analytic-coanalytic class, K-Borel* class in the previous talk. In
descriptive set theory the Borel class, the analytic-coanalytic class, and
the Borel* class are the same class, we showed that this doesn't hold in
the generalized descriptive set theory.
In this talk, we will show the consistency of "K-Borel* class is equal to
the K-analytic class". This was initially proved by Hyttinen and Weinstein
(former Kulikov), under the assumption V=L. We will show a different proof
that shows that this holds in L but also can be forced by a
cofinality-preserving GCH-preserving forcing from a model of GCH, but also
by a 3.99 \mu(A)$. We also show a more general result for the
product of two sets, which can be seen as a Brunn-Minkowski-type
inequality for sets with small measure in $\mathrm{SO}(3,\mathbb{R})$.
(Joint with Yifan Jing and Ruixiang Zhang)
Time and Place
Talk at 3:00pm
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
9th floor
room BZ 9
Please direct any questions about this talk to
matthias.aschenbrenner@univie.ac.at.
Logic Seminar today in person in S17#05-11
NUS Logic Seminar
3/15/2023 4:58:53
Hello, here just a reminder for the
talk of Liu Shixiao in the logic seminar
today at 17:00 hrs (now) on Forcing with
Density Requirements. The abstract is:
In the first half of the talk I shall be proving the
Properness of Mathias forcing with lower density
requirements. In the second half of the talk
I shall demonstrate the difficulty in applying
this method (and some other commonly used methods)
to Silver forcing with lower density requirement.
The location is S17#05-11 in the Department of
Mathematics, NUS.
Best regards, Frank
Nankai Logic Colloquium
Nankai Logic Colloquium
3/14/2023 8:02:25
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
Our speaker this week will be Konstantin Slutsky from Iowa State University. This talk is going to take place this Friday, Mar. 17, from 9am to 10am(UTC+8, Beijing time).
Title: Partial actions and orbit equivalence relations
Abstract: In this talk, we will discuss the framework of partial actions for constructing orbit equivalent actions of Polish groups. While related ideas have been employed in ergodic theory and Borel dynamics for many years, the particular viewpoint of partial actions simplifies construction of orbit equivalent actions of distinct groups.
As an application, we will present a Borel version of Katok's representation theorem for multidimensional Borel flows. One-dimensional flows are closely connected to actions of $\mathbb{Z}$ via the so-called "flow under a function" construction. This appealing geometric picture does not generalize to higher dimensions. Within the ergodic theoretical framework, Katok introduced the concept of a special flow as a way to connect multidimensional $\mathbb{R}^d$ and $\mathh{Z}^d$ actions. We will show that similar connections continue to hold in Borel dynamics.
Another illustration of the partial actions techniques that we intend to touch is the following result: a Borel equivalence relation generated by a free $\mathbb{R}$-flow can also be generated by a free action of any non-discrete and non-compact Polish group. This is in contrast with the situation for discrete groups, where amenability distinguishes groups that can and cannot generate free finite measure-preserving hyperfinite actions.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title: The 20th Nankai Logic Colloquium --Konstantin Slutsky
Time: 9:00am, Mar. 17, 2023 (Beijing Time)
Zoom Number:811 5076 2263
Passcode: 201148
Link: https://zoom.us/j/81150762263?pwd=UmdvRkVEUjI2MHlONHQrdmQrRFJyZz09
_____________________________________________________________________
Best wishes,
Ming Xiao
Charla de Cesar Corral en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
3/13/2023 11:57:15
Seminario Colombo Mexicano de Teoría de Conjuntos
Marzo 16
4:00 p.m. - 5:00 p.m. (Hora de Colombia)
Familias MAD Fin-intersecting
Cesar Corral
Universidad de York
Abstract. Diremos
que una familia MAD es pseudocompacta, si el hiperespacio de su
-espacio
lo es. Algunos resultados de Ginsgurg establecen relaciones entre propiedades del tipo compacidad de un espacio y su hiperespacio, además de que también preguntó la relación entre la pseudocompacidad de
y
la de su hiperespacio
.
Más tarde, Hrusak, Hernández y Martinez-Ruiz mostraron que existe un subespacio
de
tal
que
es
pseudocompacto pero
no
lo es. En el mismo trabajo, demostraron que, consistentemente, toda familia MAD es pseudocompacta, pero contrastantemente, también mostraron la consistencia de que hay una MAD no pseudocompacta. La existencia de familias MAD pseudocompactas en
es
aún desconocida.
Para atacar este problema, introduciremos las familias MAD Fin-intersecting, mostraremos que estas familias son pseudocompactas y mostraremos
su existencia en diferentes modelos, incluyendo algunos en los cuales la existencia de familias MAD pseudocompactas era aún desconocido.
Este
es un trabajo conjunto con Vinicius de Oliveira Rodrigues.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
Cross-Alps Logic Seminar (speaker: Victor Selivanov)
Cross-Alps Logic Seminar
3/13/2023 8:20:27
On Friday 17.03.2023 at 16.00
Victor Selivanov (Institute of Informatics Systems, Novosibirsk)
will give a talk on
Boole vs Wadge: Comparing Basic Tools of Descriptive Set Theory
Please refer to the usual webpage
of our LogicGroup for more details and the abstract of the talk. The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
All the best,Vincenzo
CosmoCaixa Barcelona: Joel Hamkins: pensament estratègic en jocs infinits
Barcelona Logic Seminar
3/13/2023 6:26:31
Dear All,
Just a reminder that you may get a 3 Euros admission fee for the Cosmocaixa museum, on the occasion of Joel hamkins’ talk. Go to the link below to get the entrance ticket and use the following code:
I strongly encourage you to attend Joel’s talk, and visit the Cosmocaixa!
See you there!
Joan
Benvolguts,
us envio l’anunci de la conferència que farà Joel Hamkins al Cosmocaixa el dia 16 de març a les 7. L’entrada val 6 Euros, però us puc donar un codi que la redueix a 3. Inclou la visita al Cosmocaixa.
Joel Hamkins: pensament estratègic en jocs infinits
https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 .
Espero que vingueu,
Joan
Dear All,
here is the announcement of the talk by Joel Hamkins he will give at Cosmocaixa (Science Museum in Barcelona) on March 16, 7pm. The entry fee is 6 Euros, but I can give you a code that reduces it to 3 Euros. It includes the entrance to the museum
Joel Hamkins: Strategic Thinking in Infinite Games
https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 .
Hope to see you there!
Joan
neal
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Wednesday seminar
Prague Set Theory Seminar
3/13/2023 5:16:47
Dear all,
The seminar meets on Wednesday March 15th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
There is no fixed program yet. Participants are encouraged to bring
their topics and questions to share.
(Chris is leaving for couple of months at the end of the week, so this
will be for some time the last opportunity to ask him something. ;-)
Best,
David
This Week in Logic at CUNY
This Week in Logic at CUNY
3/12/2023 22:44:00
This Week in Logic at CUNY:
- - - - Monday, Mar 13, 2023 - - - -
Logic and Metaphysics Workshop
Date: Monday, March 13, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Melvin Fitting (CUNY)
Title: On Kripke’s proof of Kripke completeness
Abstract: Saul Kripke announced his possible world semantics in 1959, and `published his proof of axiomatic completeness for the standard modal logics of the time in 1963. It is very unlike the standard completeness proof used today, which involves a Lindenbaum/Henkin construction and produces canonical models. Kripke’s proof involved tableaus, in a format that is difficult to follow, and uses tableau construction algorithms that are complex and somewhat error prone to describe. I will first discuss Kripke’s proof, then the historical origins of the modern version. Then I will show that completeness, proved Kripke style, could actually have been done in the Lindenbaum/Henkin way, thus simplifying things considerably. None of this is new but, with the parts collected together it is an interesting story. “In my end is my beginning”.
- - - - Tuesday, Mar 14, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, March 14, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Bartosz Wcisło, University of Gdańsk
Satisfaction classes with the full collection scheme
Satisfaction classes are subsets of models of Peano arithmetic which satisfy Tarski's compositional clauses. Alternatively, we can view satisfaction or truth classes as the extension of a fresh predicate T(x) (the theory in which compositional clauses are viewed as axioms is called CT^-).
It is easy to see that CT^- extended with a full induction scheme is not conservative over PA, since it can prove, for instance, the uniform reflection over arithmetic. By a nontrivial argument of Kotlarski, Krajewski, and Lachlan, the sole compositional axioms of CT^- in fact form a conservative extension of PA. Moreover, in order to obtain non-conservativity it is enough to add induction axioms for the Delta_0 formulae containing the truth predicate.
Answering a question of Kaye, we will show that the theory of compositional truth, CT^- with the full collection scheme is a conservative extension of Peano Arithmetic. Following the initial suggestion of Kaye, we will in fact show that any countable recursively saturated model M of PA has an elementary omega_1-like end extension M' such that M' carries a full satisfaction class.
- - - - Wednesday, Mar 15, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Jens Hemelaer, University of Antwerp.
Date and Time: Wednesday March 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: EILC toposes.
Abstract: In topos theory, local connectedness of a geometric morphism is a very geometric property, in the sense that it is stable under base change, can be checked locally, and so on. In some situations however, the weaker property of being essential is easier to verify. In this talk, we will discuss EILC toposes: toposes E such that any essential geometric morphism with codomain E is automatically locally connected. It turns out that many toposes of interest are EILC, including toposes of sheaves on Hausdorff spaces and classifying toposes of compact groups.
- - - - Thursday, Mar 16, 2023 - - - -
- - - - Friday, Mar 17, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, March 17, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Jonathan Osinski, University of Hamburg
Model-Theoretic Characterizations of Weak Vopěnka's Principle
It has been known since the 1980s that Vopěnka's Principle (VP) is equivalent to certain statements about logics, e.g. to the schema 'Every logic has a compactness cardinal.' On the other hand, it was only recently shown by Trevor Wilson that a related statement statement called Weak Vopěnka's Principle (WVP) is strictly weaker than VP. In fact, Joan Bagaria and Wilson showed that WVP is equivalent to the existence of Πn-strong cardinals for all natural numbers n. We generalize logical characterizations of strong cardinals to achieve a characterization of Πn-strong cardinals and therefore of WVP in terms of properties of strong logics. This is partly joint work with Will Boney and partly with Trevor Wilson.
Logic Workshop
CUNY Graduate Center
Friday March 17, 2:00pm-3:30pm, Room 6417
Filippo Calderoni, Rutgers University
Rotation equivalence and rigidity
The theory of countable Borel equivalence relations analyzes the actions of countable groups on Polish spaces. The main question studied is how much information is encoded by the corresponding orbit space. The amount of encoded information reflects the extent to which the action is rigid.
In this talk we will discuss rigidity results for the action of the group of rational rotations. In particular we will analyze the rotation equivalence on spheres in higher dimension. This is connected to superrigidity results of Margulis and to Zimmer’s program about the actions of discrete subgroups of Lie groups on manifolds.
Next Week in Logic at CUNY:- - - - Monday, Mar 20, 2023 - - - -Rutgers Logic Seminar
Monday, March 20, 2pm, Rutgers University, Hill 005
Roman Kossak, CUNY
Absolute Undefinability
Logic and Metaphysics WorkshopDate: Monday, March 20, 4.15-6.15pm (NY time), GC 9206NOTE: Meetings this semester are in person only (no zoom)For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/ Gregory Taylor (CUNY)
Title: First-order logics over fixed domain
Abstract: What we call first-order logic over fixed domain was initiated, in a certain guise, by Peirce around 1885 and championed, albeit in idiosyncratic form, by Zermelo in papers from the 1930s. We characterize such logics model- and proof-theoretically and argue that they constitute exploration of a clearly circumscribed conception of domain-dependent generality. Whereas a logic, or family of such, can be of interest for any of a variety of reasons, we suggest that one of those reasons might be that said logic fosters some clarification regarding just what qualifies as a logical concept, a logical operation, or a logical law.
- - - - Tuesday, Mar 21, 2023 - - - -- - - - Wednesday, Mar 22, 2023 - - - -- - - - Thursday, Mar 23, 2023 - - - -- - - - Friday, Mar 24, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Friday March 24, 2:00pm-3:30pm, Room 6417
Victoria Gitman CUNY
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
(KGRC) talks on Tuesday, March 14 and Thursday, March 16
Kurt Godel Research Center
3/10/2023 10:44:02
The KGRC welcomes as guests:
Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31.
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Lou van den Dries (host: Matthias Aschenbrenner) visits the KGRC from
March 10 to March 22.
Silvain Rideau-Kikuchi (host: Matthias Aschenbrenner) visits the KGRC from
March 15 to March 20 and gives a talk, see below.
José Nicolás Nájar Salinas (host: Miguel Moreno) visits the KGRC and gives
a talk on March 29, details to be announced at a later time.
Sergei Starchenko (host: Matthias Aschenbrenner) visits the KGRC from
April 16 to April 30 and gives a talk, details to be announced at a later
time.
* * *
For a video recording of Juris Steprāns's talk, please use
https://univienna.zoom.us/rec/share/_U6vJ6rbIaT1WaoflIav52OiR4GsAQ-W3Aw00aD4jb08xvlf7C4QoQJyD_KlQkEc.h7MOui67bVxLr9Cl
and passcode jTi%8uqf
* * *
Set Theory Research Seminar
Kurt Gödel Research Center
Tuesday, March 14
"Generalised Descriptive Set Theory, part I"
Miguel Moreno (KGRC)
This is the first of three talks about Generalised Descriptive Set Theory.
The aim of this talk is to introduce the notions of K‑Borel class,
K‑analytic class, K‑analytic-coanalytic class, K‑Borel* class, and show
the relation between these classes.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
(Students at Uni Wien are required to attend in person.)
Please direct any other questions about this talk to
vera.fischer@univie.ac.at.
* * *
Logic Colloquium
Kurt Gödel Research Center
Thursday, March 16
"Multi topological fields, approximations and NTP2"
Silvain Rideau-Kikuchi (U Paris Diderot, FR)
(Joint work with S. Montenegro)
The striking resemblance between the behaviour of pseudo-algebraically
closed, pseudo real closed and pseudo p-adically fields has lead to
numerous attempts at describing their properties in a unified manner. In
this talk I will present another of these attempts: the class of
pseudo-T-closed fields, where T is an enriched theory of fields. These
fields verify a « local-global » principle with respect to models of T for
the existence of points on varieties. Although it very much resembles
previous such attempts, our approach is more model theoretic in flavour,
both in its presentation and in the results we aim for.
The first result I would like to present is an approximation result,
generalising a result of Kollar on PAC fields, respectively Johnson on
henselian fields. This result can be rephrased as the fact that
existential closeness in certain topological enrichments come for free
from existential closeness as a field. The second result is a (model
theoretic) classification result for bounded pseudo-T-closed fields, in
the guise of the computation of their burden. One of the striking
consequence of these two results is that a bounded perfect PAC field with
n independent valuations has burden n and, in particular, is NTP2.
Time and Place
Talk at 3:00pm in hybrid mode: on-site as well as via Zoom
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
2nd floor
room HS 11
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
(Students at Uni Wien are required to attend in person.)
Please direct any other questions about this talk to
matthias.aschenbrenner@univie.ac.at.
Nankai Logic Colloquium
Nankai Logic Colloquium
3/6/2023 22:47:15
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Vladimir Kanovei from the Institute for Information Transmission Problems, RAS. This talk is going to take place this Friday, Mar.10, from 4pm to 5pm(UTC+8, Beijing time).
Title:
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic
Abstract
Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories.
Given an axiom schema S, we let S* be the parameter-free sub-schema.
Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions.
In particular, Kreisel noted that
[...] if one is convinced of the significance of something like agiven axiom schema, it is natural to study details, such as the effect of parameters.
This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title: The 19th Nankai Logic Colloquium --Vladimir Kanovei
Time: 16:00pm, Mar. 10, 2023 (Beijing Time)
Zoom Number:844 4116 3813
Passcode: 628524
Link: https://zoom.us/j/84441163813?pwd=WFlSbThMbldUeVZYZncrTGVyYmp5QT09
_____________________________________________________________________
Best wishes,
Ming Xiao
UPDATE - This Week in Logic at CUNY
This Week in Logic at CUNY
3/6/2023 10:34:51
Hi everyone,
A quick update - Unfortunately, Dr. Weinert will be unable to speak on March 10, so the Logic Workshop is canceled this week.
Best,
Jonas
This Week in Logic at CUNY:
- - - - Monday, Mar 6, 2023 - - - -
Rutgers Logic Seminar
Monday, March 6, 2pm, Rutgers University, Hill 005
Will Adkisson, UIC
The Strong and Super Tree Property
Logic and Metaphysics Workshop
Date: Monday, March 6, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Gary Ostertag (CUNY/Mount Sinai)
Title: Lewis on accommodation and representation de re
Abstract: Recall Lumpl, the lump of clay out of which the statue Goliath is fashioned. While (1) ‘Lumpl could have survived a squashing’ is true, (2) ‘Goliath could have survived a squashing’ is false, it being after all essential to Goliath, but not to Lumpl, that it be a statue. We have here an example of what David Lewis (1986) called “the inconstancy of representation de re”. For Lewis, the inconstancy does not amount to inconsistency, but rather points to the context-sensitivity of de re modal predication: (1) and (2) make implicit, context-sensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truth-conditional judgments are fully consistent. As I show, however, the conversational rule that triggers the implicit reference not only fails to license the reference shift, it effectively prohibits it. The upshot is that counterpart theory is deprived of a central motivation.
- - - - Tuesday, Mar 7, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, March 7, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Bellaouar Djamel, University 08 Mai 1945 Guelma
Some generalizations on the representation of unlimited natural numbers
Based on permanence principles of nonstandard analysis and as a continuation of the papers [1-3], we present some notes and questions on the representation of unlimited natural numbers. As a natural generalization, let A be an unlimited m by n matrix with integer entries (i.e one of its integer entries is unlimited). Here we prove that every unlimited matrix A with integer entries can be written as the sum of a limited matrix S with integer entries and the product of two unlimited matrices W1 and W2 with integer entries, that is, A=S+W1⋅W2. For further research, we propose several matrix representation forms.
Finally, we consider the numbers of the form z=a+bi where a,b are integers, which are called Gaussian integers. In the case when a or b is unlimited, the number z=a+bi is said to be unlimited. Also, some notes on the representation of unlimited Gaussian integers are given.
[1] A. Boudaoud, La conjecture de Dickson et classes particulière d'entiers, Ann. Math. Blaise Pascal. 13 (2006), 103-109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 1-31.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 1-6.
- - - - Wednesday, Mar 8, 2023 - - - -
- - - - Thursday, Mar 9, 2023 - - - -
- - - - Friday, Mar 10, 2023 - - - -
Logic Workshop - TODAY'S WORKSHOP IS CANCELLED
CUNY Graduate Center
Friday March 10, 2:00pm-3:30pm, Room 6417
Set Theory Seminar
CUNY Graduate Center
Friday, March 10, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. James Holland, Rutgers University
Next Week in Logic at CUNY:
- - - - Monday, Mar 13, 2023 - - - -
Logic and Metaphysics Workshop
Date: Monday, March 13, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Melvin Fitting (CUNY)
Title: On Kripke’s proof of Kripke completeness
Abstract: Saul Kripke announced his possible world semantics in 1959, and `published his proof of axiomatic completeness for the standard modal logics of the time in 1963. It is very unlike the standard completeness proof used today, which involves a Lindenbaum/Henkin construction and produces canonical models. Kripke’s proof involved tableaus, in a format that is difficult to follow, and uses tableau construction algorithms that are complex and somewhat error prone to describe. I will first discuss Kripke’s proof, then the historical origins of the modern version. Then I will show that completeness, proved Kripke style, could actually have been done in the Lindenbaum/Henkin way, thus simplifying things considerably. None of this is new but, with the parts collected together it is an interesting story. “In my end is my beginning”.
- - - - Tuesday, Mar 14, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, March 14, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Bartosz Wcisło, University of Gdańsk
- - - - Wednesday, Mar 15, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Jens Hemelaer, University of Antwerp.
Date and Time: Wednesday March 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: EILC toposes.
Abstract: In topos theory, local connectedness of a geometric morphism is a very geometric property, in the sense that it is stable under base change, can be checked locally, and so on. In some situations however, the weaker property of being essential is easier to verify. In this talk, we will discuss EILC toposes: toposes E such that any essential geometric morphism with codomain E is automatically locally connected. It turns out that many toposes of interest are EILC, including toposes of sheaves on Hausdorff spaces and classifying toposes of compact groups.
- - - - Thursday, Mar 16, 2023 - - - -
- - - - Friday, Mar 17, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, March 17, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Jonathan Osinski, University of Hamburg
Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 17, 2:00pm-3:30pm, Room 6417
Filippo Calderoni, Rutgers University
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
Charla de Paul Szeptycki en el Seminario Colombo Mexicano de Teoría de Conjuntos
Seminario Colombo Mexicano de Teoría de Conjuntos
3/6/2023 9:25:02
Seminario Colombo Mexicano de Teoría de Conjuntos
March 9
4:00 p.m. - 5:00 p.m. (Colombia time)
A Ramsey-theoretic strengthening of
sequential compactness
Paul Szeptycki
York University
Abstract. We
define a topological space $X$ to be $n$-Ramsey if for every map $f: [\omega]^n \rightarrow X$ there is an infinite set $M$ and a point $x \in X$ such that $f \uphaproonright [M]^n$ converges to $x$ in a natural sense. Sequentially compact spaces are precisely
the $1$-Ramsey spaces and any $n+1$-Ramsey space is $n$-Ramsey. We discuss basic results about these new classes
of spaces, directions of current work in progress and some open problems.
Zoom meeting information.
Meeting ID: 856
1882 0721
Passcode: 123456
Zoom is the leader in modern enterprise video communications, with an easy, reliable cloud platform for video and audio conferencing, chat, and webinars across mobile, desktop, and room systems. Zoom Rooms is the original software-based conference room solution
used around the world in board, conference, huddle, and training rooms, as well as executive offices and classrooms. Founded in 2011, Zoom helps businesses and organizations bring their teams together in a frictionless environment to get more done. Zoom is
a publicly traded company headquartered in San Jose, CA.
cuaieed-unam.zoom.us
|
This Week in Logic at CUNY
This Week in Logic at CUNY
3/5/2023 22:46:00
This Week in Logic at CUNY:
- - - - Monday, Mar 6, 2023 - - - -
Rutgers Logic Seminar
Monday, March 6, 2pm, Rutgers University, Hill 005
Will Adkisson, UIC
The Strong and Super Tree Property
Logic and Metaphysics Workshop
Date: Monday, March 6, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Gary Ostertag (CUNY/Mount Sinai)
Title: Lewis on accommodation and representation de re
Abstract: Recall Lumpl, the lump of clay out of which the statue Goliath is fashioned. While (1) ‘Lumpl could have survived a squashing’ is true, (2) ‘Goliath could have survived a squashing’ is false, it being after all essential to Goliath, but not to Lumpl, that it be a statue. We have here an example of what David Lewis (1986) called “the inconstancy of representation de re”. For Lewis, the inconstancy does not amount to inconsistency, but rather points to the context-sensitivity of de re modal predication: (1) and (2) make implicit, context-sensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truth-conditional judgments are fully consistent. As I show, however, the conversational rule that triggers the implicit reference not only fails to license the reference shift, it effectively prohibits it. The upshot is that counterpart theory is deprived of a central motivation.
- - - - Tuesday, Mar 7, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, March 7, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Bellaouar Djamel, University 08 Mai 1945 Guelma
Some generalizations on the representation of unlimited natural numbers
Based on permanence principles of nonstandard analysis and as a continuation of the papers [1-3], we present some notes and questions on the representation of unlimited natural numbers. As a natural generalization, let A be an unlimited m by n matrix with integer entries (i.e one of its integer entries is unlimited). Here we prove that every unlimited matrix A with integer entries can be written as the sum of a limited matrix S with integer entries and the product of two unlimited matrices W1 and W2 with integer entries, that is, A=S+W1⋅W2. For further research, we propose several matrix representation forms.
Finally, we consider the numbers of the form z=a+bi where a,b are integers, which are called Gaussian integers. In the case when a or b is unlimited, the number z=a+bi is said to be unlimited. Also, some notes on the representation of unlimited Gaussian integers are given.
[1] A. Boudaoud, La conjecture de Dickson et classes particulière d'entiers, Ann. Math. Blaise Pascal. 13 (2006), 103-109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 1-31.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 1-6.
- - - - Wednesday, Mar 8, 2023 - - - -
- - - - Thursday, Mar 9, 2023 - - - -
- - - - Friday, Mar 10, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 10, 2:00pm-3:30pm, Room 6417
Thilo Weinert, University of Vienna
Set Theory Seminar
CUNY Graduate Center
Friday, March 10, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. James Holland, Rutgers University
Next Week in Logic at CUNY:
- - - - Monday, Mar 13, 2023 - - - -
Logic and Metaphysics Workshop
Date: Monday, March 13, 4.15-6.15pm (NY time), GC 9206
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Melvin Fitting (CUNY)
Title: On Kripke’s proof of Kripke completeness
Abstract: Saul Kripke announced his possible world semantics in 1959, and `published his proof of axiomatic completeness for the standard modal logics of the time in 1963. It is very unlike the standard completeness proof used today, which involves a Lindenbaum/Henkin construction and produces canonical models. Kripke’s proof involved tableaus, in a format that is difficult to follow, and uses tableau construction algorithms that are complex and somewhat error prone to describe. I will first discuss Kripke’s proof, then the historical origins of the modern version. Then I will show that completeness, proved Kripke style, could actually have been done in the Lindenbaum/Henkin way, thus simplifying things considerably. None of this is new but, with the parts collected together it is an interesting story. “In my end is my beginning”.
- - - - Tuesday, Mar 14, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, March 14, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Bartosz Wcisło, University of Gdańsk
- - - - Wednesday, Mar 15, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Speaker: Jens Hemelaer, University of Antwerp.
Date and Time: Wednesday March 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: EILC toposes.
Abstract: In topos theory, local connectedness of a geometric morphism is a very geometric property, in the sense that it is stable under base change, can be checked locally, and so on. In some situations however, the weaker property of being essential is easier to verify. In this talk, we will discuss EILC toposes: toposes E such that any essential geometric morphism with codomain E is automatically locally connected. It turns out that many toposes of interest are EILC, including toposes of sheaves on Hausdorff spaces and classifying toposes of compact groups.
- - - - Thursday, Mar 16, 2023 - - - -
- - - - Friday, Mar 17, 2023 - - - -
Set Theory Seminar
CUNY Graduate Center
Friday, March 17, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Jonathan Osinski, University of Hamburg
Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 17, 2:00pm-3:30pm, Room 6417
Filippo Calderoni, Rutgers University
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
Barcelona Set Theory Seminar
Barcelona Logic Seminar
3/4/2023 11:13:28
Dear All,
Please find attached the announcement of the next Barcelona Set Theory Seminar session.
SPEAKER: Radek Honzik
TITLE: Compactness principles at small cardinals and their preservation
DATE: Wednesday, 8 March 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:
Meeting ID: 985 6524 7347
Passcode: 243408
Best regards,
Joan
P.S.: If you do not wish to receive any more announcements, please send an email to
bagaria@ub.edu with the text “Unsubscribe”.
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Wednesday seminar
Prague Set Theory Seminar
3/3/2023 9:24:32
Dear all,
The seminar meets on Wednesday March 8th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Chris Lambie-Hanson -- Topics in cardinal arithmetic
We will discuss some recent results and some not-so-recent results in
cardinal arithmetic and PCF theory. The precise topics will depend on
the interests of the audience and the preparedness of the speaker but
may include: existence theorems about PCF-theoretic scales, Silver's
theorem for pseudopowers, the cov vs. pp problem, or recent work of the
speaker showing that a generalized narrow system property implies
Shelah's Strong Hypothesis.
Best,
David
(KGRC) two talks at U Wien and TU Wien
Kurt Godel Research Center
3/2/2023 10:31:00
The KGRC welcomes as guests:
Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31.
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Juris Steprāns (host: Vera Fischer) visits the KGRC from March 6 to March
10 and gives a talk, see below.
Lou van den Dries (host: Matthias Aschenbrenner) visits the KGRC from
March 10 to March 22.
Silvain Rideau-Kikuchi (host: Matthias Aschenbrenner) visits the KGRC from
March 15 to March 20 and gives a talk, details to be announced at a later
time.
* * *
Set Theory Research Seminar
Kurt Gödel Research Center
Tuesday, March 7
"Selective and Milliken-Taylor ultrafilters"
Juris Steprāns (York U, CA)
I will report on joint work with Dilip Raghavan solving a question of
Blass about whether the existence of many selective ultrafilters implies
the existence of Milliken-Taylor ultrafilters. The first part of the talk
will provide the historical context of what was known in the mid 80s that
prompted Blass to ask his question. The second part will discuss the key
technical advance in our argument.
Time and Place
Talk at 3:00pm
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Please direct any questions about this talk to vera.fischer@univie.ac.at.
* * *
FG1 Seminar
Algebra Research Unit
Wednesday, March 8
"Various ways to compare spaces, subsets, and functions"
Raphaël Carroy (Università degli Studi di Torino, IT)
One can consider a quasi-order like topological embeddability when one
wants to compare a Polish (or analytic) space to another. If instead one
tries to rank the complexities emerging among subsets of a given space,
continuous reducibility becomes relevant. Both these quasi-orders have
extensions to functions between Polish (or analytic) spaces. Some natural
questions about these quasi-orders are then: the existence of simple
bases, characterizing the simplicity or complexity of the quasi-order in
itself, and describing it when it turns out to be simple enough.
I will try to give some context on these quasi-orders and review known and
more recent results and applications.
Times and Places
Snacks and beverages at 2:00pm
Institute of Discrete Mathematics and Geometry
TU Wien
Wiedner Hauptstrasse 8-10
1040 Wien
Austria
5th floor, green part
room Besprechungsraum DA 05 C22
Talk at 2:45pm
Institute of Discrete Mathematics and Geometry
TU Wien
Wiedner Hauptstrasse 8-10
1040 Wien
Austria
8th floor, green part
room Dissertantenraum DA 08 B19
Please direct any questions about this talk to
sandra.mueller@tuwien.ac.at.
CosmoCaixa Barcelona: Joel Hamkins: pensament estratègic en jocs infinits
Barcelona Logic Seminar
3/2/2023 9:02:35
Benvolguts,
us envio l’anunci de la conferència que farà Joel Hamkins al Cosmocaixa el dia 16 de març a les 7. L’entrada val 6 Euros, però us puc donar un codi que la redueix a 3. Inclou la visita al Cosmocaixa.
Joel Hamkins: pensament estratègic en jocs infinits
https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 .
Espero que vingueu,
Joan
Dear All,
here is the announcement of the talk by Joel Hamkins he will give at Cosmocaixa (Science Museum in Barcelona) on March 16, 7pm. The entry fee is 6 Euros, but I can give you a code that reduces it to 3 Euros. It includes the entrance to the museum
Joel Hamkins: Strategic Thinking in Infinite Games
https://cosmocaixa.org/ca/p/pensament-estrategic-en-jocs-infinits_a122155152 .
Hope to see you there!
Joan
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Logic Seminar 8 March 2023 17:00 hrs at NUS by Chong Chitat
NUS Logic Seminar
3/2/2023 3:58:53
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 8 March 2023, 17:00 hrs
Place: NUS, Department of Mathematics, S17#05-11
Speaker: Chong Chitat, National University of Singapore
Title: Proof-theoreitic strength of the Halpern-Lauchli Theorem
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Abstract:
Let T be the full infinite binary tree (i.e. the Cantor space). An
infinite subtree S of T is a strong subtree if (i) S is isomorphic to
T, (ii) if sigma is a node in S, and sigma_0, sigma_1 are its
immediate successors in S, then sigma_0 and sigma_1 have the same
length in T and furthermore (iii) the intersection of sigma_0 and
sigma_1 is sigma.
The Halpern-Lauchli Theorem is a theorem in combinatorial mathematics
which states that for any finite number of infinite full binary trees
T_1,T_2,..., T_d, and any finite coloring of the d-row vectors in T_1 x
T_2 x ... x T_d, there exist strong subtrees S_1 subseteq T_1, S_2 subseteq
T_2, ..., S_d subseteq T_d for which all d-row vectors in
S_1 x S_2 x ... x S_d have the same color.
This Ramsey type theorem is yet another striking demonstration of the
existence of order within chaotic disorder. There is no known simple
proof of this theorem in the published literature.
In this talk we discuss the proof-theoretic strength of the
Halpern-Lauchli theorem from the reverse mathematics point of view. In
particular, we give a characterisation of the inductive strength of
this theorem as well as its conservation strength over a base theory
weaker than Sigma_2-induction.
This is joint work with Li Wei and Yang Yue.
Today's Logic Seminar is via Zoom
NUS Logic Seminar
3/1/2023 3:29:00
Hello, please note that today's talk is by Zoom and there
is no physical meeting. Here again the login info:
Return-Path:
Date: Fri, 24 Feb 2023 15:00:41 +0800
From: Frank STEPHAN
To: matyangy@nus.edu.sg, settheorytalks@gmail.com, belanger@nus.edu.sg,
Subject: Logic Seminar 1 March 2023 17:00 hrs Singapore time by Linus Richter
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 1 March 2023, 17:00 hrs
Place: NUS, Department of Mathematics, Talk via Zoom:
https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
Meeting ID: 830 4925 8042
Passcode: 1729=x3+y3
Speaker: Linus Richter, Victoria University of Wellington
Title: Co-analytic Counterexamples to Marstrand's Projection Theorem
Abstract: A recent "point-to-set principle" of Jack Lutz and Neil Lutz
characterises the Hausdorff dimension of any subset of Euclidean space
in terms of the Kolmogorov complexity of its individual points.
Sets with particular fractal properties can now be constructed
point-by-point, by coding "enough" information into each point, bit-by-bit.
After introducing the point-to-set principle, I will present a new result
in fractal geometry: under V=L (the axiom of constructiblity),
I will outline the construction of co-analytic sets of Euclidean
space which fail Marstrand's Projection Theorem, a classical result
in fractal geometry concerning the dimension of orthogonal projections
of analytic plane sets onto lines.
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Nankai Logic Colloquium
Nankai Logic Colloquium
2/27/2023 22:39:50
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Martino Lupini from the University of Bologna. This talk is going to take place this Friday, Mar. 03, from 16:00 to 17:00 (UTC+8, Beijing time).
Title: Definable refinements of classical algebraic invariants
Abstract: In this talk I will explain how methods from logic allow one to construct refinements of classical algebraic invariants that are endowed with additional topological and descriptive set-theoretic information. This approach brings to fruition initial insights due to Eilenberg, Mac Lane, and Moore (among others) with the additional ingredient of recent advanced tools from logic. I will then present applications of this viewpoint to invariants from a number of areas in mathematics, including operator algebras, group theory, algebraic topology, and homological algebra.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title: The 18th Nankai Logic Colloquium --Martino Lupini
Time: 16:00, Mar. 3, 2023 (Beijing Time)
Zoom Number:859 1679 0296
Passcode: 577088
Link: https://zoom.us/j/85916790296?pwd=WGRrZjJKa0kvRE9KSGtxNkJia2JiUT09
_____________________________________________________________________
Best wishes,
Ming Xiao
Cross-Alps Logic Seminar (speaker: Dugald MacPherson)
Cross-Alps Logic Seminar
2/27/2023 11:53:59
On Friday 03.03.2023 at 16.00
Dugald MacPherson (University of Leeds)
will give a talk on
Uniform families of definable sets in finite structures
Please refer to the usual webpage
of our LogicGroup for more details and the abstract of the talk. The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
All the best,Vincenzo
(KGRC) Logic Colloquium talk on Thursday, March 2
Kurt Godel Research Center
2/27/2023 10:24:16
The KGRC welcomes as guests:
Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31.
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Jerzy Kąkol (host: Damian Sobota) visits the KGRC until March 3.
Manuel López Pellicer (host: Damian Sobota) visits the KGRC until March 3.
Katrin Tent (host: Matthias Aschenbrenner) visits the KGRC from March 1 to
March 5 and gives a talk (see below).
Juris Steprāns (host: Vera Fischer) visits the KGRC from March 6 to March
10 and gives a talk, details to be announced at a later time.
Silvain Rideau-Kikuchi (host: Matthias Aschenbrenner) visits the KGRC from
March 15 to March 20 and gives a talk, details to be announced at a later
time.
* * *
Logic Colloquium
Kurt Gödel Research Center
Thursday, March 2
"Simplicity of automorphism groups of homogeneous structures"
Katrin Tent (Universität Münster, DE)
We discuss some general criteria that can be used to show that the
automorphism group of a homogeneous structure (such as metric space,
right-angled building, graph or hypergraphs) are simple groups or have
simple quotients.
Time and Place
Talk at 3:00pm
Universität Wien
Institut für Mathematik
Oskar-Morgenstern-Platz 1
1090 Wien
2nd floor room HS 11
If you would like to follow the talk online, please let Matthias
Aschenbrenner (matthias.aschenbrenner@univie.ac.at) or Vera Fischer
(vera.fischer@univie.ac.at) know in advance and we will arrange for it to
be streamed.
Wednesday seminar
Prague Set Theory Seminar
2/27/2023 6:31:41
Dear all,
The seminar meets on Wednesday March 1st at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
The program is not yet determined. If anybody is interested in speaking
or to hear something specific, do let me know.
Best,
David
This Week in Logic at CUNY
This Week in Logic at CUNY
2/26/2023 22:34:00
This Week in Logic at CUNY:
- - - - Monday, Feb 27, 2023 - - - -
Rutgers Logic Seminar
Monday, February 27, 2pm, Rutgers University, Hill 005
Leonardo Nagami Coregliano, IAS Princeton
Ramsey's Theorem in the countable and weak randomness
Logic and Metaphysics Workshop
Date: Monday, February 27, 4.15-6.15pm (NY time), GC 9205
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Lionel Shapiro, UConn
Title: Neopragmatism and logic: A deflationary proposal
Abstract: Neopragmatists seek to sidestep metaphysical puzzles by shifting the target of philosophical explanation from the objects we think and talk about to the functions of expressions and concepts in our cognitive economy. Logical vocabulary can serve as a target for neopragmatist inquiry, and it has also posed obstacles to neopragmatist accounts of other vocabulary. I will argue that the obstacles can be addressed by adopting a neopragmatist perspective toward logical relations, such as logical consequence, and toward propositional content. Doing so calls into question two purported constraints on explanations of the functions of logical connectives. I will sketch an account made possible by rejecting those constraints, one according to which logical connectives serve to express dialectical attitudes. The proposal is deflationary in two ways: it rests on an extension of deflationism from truth to logical relations, and it aims to deflate some of neopragmatists’ theoretical ambitions.
- - - - Tuesday, Feb 28, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 28, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Zuzana Hanikova, Czech Academy of Sciences
Vopěnka's Alternative Set Theory and its mathematical context
Vopěnka first presented his Alternative Set Theory (AST) in the monograph 'Mathematics in the Alternative Set Theory' published by Teubner, Leipzig in 1979. Another book presenting the theory, 'Introduction to Mathematics in the Alternative Set Theory', was published in 1989 in Slovak by Alfa, Bratislava. In addition there are numerous journal papers on the AST by members of the research group established by Vopěnka, and the proceedings of a conference dedicated to the AST, also from 1989. In several essays, Vopěnka sought to lay out the motivation and philosophical import of the AST and some of his subsequent work. As one consequence of the emphasis on his philosophy, the mathematical inspiration for the AST has been somewhat obliterated. The aim of the talk is to discuss the design choices Vopěnka made for the AST in relation to pertinent mathematical developments of the 20th century, such as Skolem's work on nonstandard models of arithmetic, Robinson's nonstandard analysis, Rieger's nonstandard models of arithmetic, Vopěnka's nonstandard model of set theory, Vopěnka and Hájek's theory of semisets, or Parikh's almost consistent theories. The presentation will include an outline of the AST following the works of Vopěnka and Sochor. This is a historical talk; no new mathematical results on the AST will be presented.
- - - - Wednesday, Mar 1, 2023 - - - -
- - - - Thursday, Mar 2, 2023 - - - -
- - - - Friday, Mar 3, 2023 - - - -
Next Week in Logic at CUNY:
- - - - Monday, Mar 6, 2023 - - - -
Rutgers Logic Seminar
Monday, March 6, 2pm, Rutgers University, Hill 005
Will Adkisson, UIC
Logic and Metaphysics Workshop
Date: Monday, March 6, 4.15-6.15pm (NY time), GC 9205
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Gary Ostertag (CUNY/Mount Sinai)
Title: Lewis on accommodation and representation de re
Abstract: Recall Lumpl, the lump of clay out of which the statue Goliath is fashioned. While (1) ‘Lumpl could have survived a squashing’ is true, (2) ‘Goliath could have survived a squashing’ is false, it being after all essential to Goliath, but not to Lumpl, that it be a statue. We have here an example of what David Lewis (1986) called “the inconstancy of representation de re”. For Lewis, the inconstancy does not amount to inconsistency, but rather points to the context-sensitivity of de re modal predication: (1) and (2) make implicit, context-sensitive reference to different counterpart relations. Once we recognize this, Lewisians argue, it becomes clear how our intuitive truth-conditional judgments are fully consistent. As I show, however, the conversational rule that triggers the implicit reference not only fails to license the reference shift, it effectively prohibits it. The upshot is that counterpart theory is deprived of a central motivation.
- - - - Tuesday, Mar 7, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, March 7, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Bellaouar Djamel, University 08 Mai 1945 Guelma
Some generalizations on the representation of unlimited natural numbers
Based on permanence principles of nonstandard analysis and as a continuation of the papers [1-3], we present some notes and questions on the representation of unlimited natural numbers. As a natural generalization, let A be an unlimited m by n matrix with integer entries (i.e one of its integer entries is unlimited). Here we prove that every unlimited matrix A with integer entries can be written as the sum of a limited matrix S with integer entries and the product of two unlimited matrices W1 and W2 with integer entries, that is, A=S+W1⋅W2. For further research, we propose several matrix representation forms.
Finally, we consider the numbers of the form z=a+bi where a,b are integers, which are called Gaussian integers. In the case when a or b is unlimited, the number z=a+bi is said to be unlimited. Also, some notes on the representation of unlimited Gaussian integers are given.
[1] A. Boudaoud, La conjecture de Dickson et classes particulière d'entiers, Ann. Math. Blaise Pascal. 13 (2006), 103-109.
[2] A. Boudaoud and D. Bellaouar, Representation of integers: A nonclassical point of view, J. Log. Anal. 12:4 (2020) 1-31.
[3] K. Hrbacek, On Factoring of unlimited integers, J. Log. Anal. 12:5 (2020) 1-6.
- - - - Wednesday, Mar 8, 2023 - - - -
- - - - Thursday, Mar 9, 2023 - - - -
- - - - Friday, Mar 10, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Modality TBA
Friday March 10, 2:00pm-3:30pm, Room 6417
Thilo Weinert, University of Vienna
Set Theory Seminar
CUNY Graduate Center
Friday, March 10, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. James Holland, Rutgers University
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
Barcelona Set Theory Seminar
Barcelona Logic Seminar
2/25/2023 2:50:59
Dear All,
Please find attached the announcement of the next Barcelona Set Theory Seminar session.
SPEAKER: Boriša Kuzeljević
TITLE: Lower bounds of sets of P-points
DATE: Wednesday, 29 February 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:
Meeting ID: 985 6524 7347
Passcode: 243408
Best regards,
Joan
P.S.: If you do not wish to receive any more announcements, please send an email to
bagaria@ub.edu with the text “Unsubscribe”.
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
BLAST in Charlottle NC: May 16-20, 2023
Conference
2/24/2023 13:53:57
We would like to bring your attention to the upcoming BLAST 2023 conference, which will take place at the University of North Carolina, Charlotte, from May 16 - 20.
BLAST is a conference series focusing on Boolean Algebras, Lattices, Universal Algebra and Model Theory, Set Theory, and Topology. We hope that you will be able to attend the conference, and to contribute a talk.
The confirmed invited speakers for the conference are:
- Marco Abbadini, University of Salerno
- Dana Bartošová, University of Florida
- William Chan, University of North Texas
- Daniel Herden, Baylor University
- Andre Kornell, Dalhousie University
- David Stanovský, Charles University
Additionally, we can confirm that a tutorial will be given by
- Keith Kearnes, University of Colorado Boulder
The website for this conference is still under construction, but a preliminary version can be found here: https://pages.charlotte.edu/blast2023/. The home website for the BLAST conference series can be found here: https://math.colorado.edu/blast/.
Some financial support, provided by the National Science Foundation, is available for students and young researchers.
Tagged: Marco Abbadini, Dana Bartošová, William Chan, Daniel Herden, Andre Kornell, David Stanovský, Keith Kearnes
CMU Math Logic Seminar next Tuesday
Carnegie Mellon Logic Seminar
2/24/2023 10:53:57
TUESDAY, February 28, 2023
Mathematical Logic Seminar: 3:30-4:30 PM Eastern,
Online, Marcin Sabok, McGill University
Join Zoom Meeting:
https://cmu.zoom.us/j/92655324096?pwd=VUhSSlkrdHMxbTlSYUMxYzFXM01kdz09Meeting ID: 926 5532 4096
Passcode: 555455
TITLE: Perfect matchings in hyperfinite graphings
ABSTRACT: The talk will focus on recent results on measurable perfect matchings in hyperfinite graphings. In particular, we will discuss a result saying that every regular hyperfinite one-ended bipartite graphing admits a measurable perfect matching. We will also see some applications of these results, answering several questions in the field. For instance we will characterize the existence of factor of iid perfect matchings in bipartite Cayley graphs, extending a result of Lyons and Nazarov. We will also answer a question of Bencs, Hruskova and Toth arising in the study of balanced orientations in graphings. Finally, we see how the results imply the measurable circle squaring. This is joint work with Matt Bowen and Gabor Kun.
Logic Seminar 1 March 2023 17:00 hrs Singapore time by Linus Richter at NUS via Zoom
NUS Logic Seminar
2/24/2023 2:00:41
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 1 March 2023, 17:00 hrs
Place: NUS, Department of Mathematics, Talk via Zoom:
https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
Meeting ID: 830 4925 8042
Passcode: 1729=x3+y3
Speaker: Linus Richter, Victoria University of Wellington
Title: Co-analytic Counterexamples to Marstrand's Projection Theorem
Abstract: A recent "point-to-set principle" of Jack Lutz and Neil Lutz
characterises the Hausdorff dimension of any subset of Euclidean space
in terms of the Kolmogorov complexity of its individual points.
Sets with particular fractal properties can now be constructed
point-by-point, by coding "enough" information into each point, bit-by-bit.
After introducing the point-to-set principle, I will present a new result
in fractal geometry: under V=L (the axiom of constructiblity),
I will outline the construction of co-analytic sets of Euclidean
space which fail Marstrand's Projection Theorem, a classical result
in fractal geometry concerning the dimension of orthogonal projections
of analytic plane sets onto lines.
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Nankai Logic Colloquium
Nankai Logic Colloquium
2/22/2023 20:20:08
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the morning.
Our speaker this week will be Slawomir Solecki from Cornell University. This talk is going to take place this Friday, Feb.24, 2023, from 9am to 10am (UTC+8, Beijing time).
Title: Descriptive Set Theory and closed groups generated by generic measure preserving transformations
Abstract: The subject matter of the talk lies within the area that employs the descriptive set theoretic point of view in the study of large topological groups.
The behavior of a measure preserving transformation, even a generic one, is highly non-uniform. In contrast to this observation, a different picture of a very uniform behavior of the closed group generated by a generic measure preserving transformation $T$ has emerged. This picture included substantial evidence that pointed to these groups (for a generic $T$) being all topologically isomorphic to a single group, namely, $L^0$---the topological group of all Lebesgue measurable functions from $[0,1]$ to the circle. In fact, Glasner and Weiss asked if this is the case.
We will describe the background touched on above, including the descriptive set theoretic background. We will indicate a proof of the following theorem that answers the Glasner--Weiss question in the negative: for a generic measure preserving transformation $T$, the closed group generated by $T$ is {\bf not} topologically isomorphic to $L^0$.
____________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title: The 17th Nankai Logic Colloquium --Slawomir Solecki
Time: 9:00am, Feb. 24, 2023 (Beijing Time)
Zoom Number:854 3647 9165
Passcode: 977845
Link: https://zoom.us/j/85436479165?pwd=cjFwZlpUZWtCcnhTci9OK0R5ODU0UT09
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
This Week in Logic at CUNY
2/19/2023 22:31:00
This Week in Logic at CUNY:
- - - - Monday, Feb 13, 2023 - - - -
Rutgers Logic Seminar
Monday, February 13, 2pm, Rutgers University, Hill 005
James Holland, Rutgers
Forcing more choice over the Chang model
- - - - Tuesday, Feb 14, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 14, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id) Vladimir Kanovei, Institute for Information Transmission Problems
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic
Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories. Given an axiom schema S, we let S* be the parameter-free sub-schema.
Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions. In particular, Kreisel noted that
[...] if one is convinced of the significance of something like a given axiom schema, it is natural to study details, such as the effect of parameters.This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.
- - - - Wednesday, Feb 15, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Second Lecture.
Speaker: Mee Seong Im, United States Naval Academy, Annapolis.
Date and Time: Wednesday February 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Automata and topological theories.
Abstract: Theory of regular languages and finite state automata is part of the foundations of computer science. Topological quantum field theories (TQFT) are a key structure in modern mathematical physics. We will interpret a nondeterministic automaton as a Boolean-valued one-dimensional TQFT with defects labelled by letters of the alphabet for the automaton. We will also describe how a pair of a regular language and a circular regular language gives rise to a lax one-dimensional TQFT.
- - - - Thursday, Feb 16, 2023 - - - -
- - - - Friday, Feb 17, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Friday February 17, 2:00pm-3:30pm, Room 6417
Russell Miller, CUNY
Computability and the Absolute Galois Group of Q
Fix a computable presentation ¯¯¯¯Q of the algebraic closure of the rational numbers. The absolute Galois group of the rational numbers, which is precisely the automorphism group of the field ¯¯¯¯Q, may then be viewed as a collection of paths through a finite-branching tree. Each individual automorphism has a Turing degree. We will use known results in computability to try to build natural countable elementary subgroups of the absolute Galois group. Several intriguing questions in number theory will appear as we measure the extent to which we succeed in doing so.
Next Week in Logic at CUNY:
- - - - Monday, Feb 20, 2023 - - - -
- - - - Tuesday, Feb 21, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 21, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Alexei Miasnikov, Stevens Institute of Technology
First-order classification and non-standard models
In this talk I will discuss some recent advances in the first-order classification problem. I will touch on first-order rigidity and quasi finite axiomatization. However, the main point of the presentation is on how, in principle, one can describe all structures which are first-order equivalent to a given one. This leads to non-standard models of algebraic structures (aka non-standard analysis or non-standard arithmetic), which are interesting in their own right.
- - - - Wednesday, Feb 22, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Third Lecture.
Speaker: Joshua Sussan, CUNY.
Date and Time: Wednesday February 22, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Non-semisimple Hermitian TQFTs.
Abstract: Topological quantum field theories coming from semisimple categories build upon interesting structures in representation theory and have important applications in low dimensional topology and physics. The construction of non-semisimple TQFTs is more recent and they shed new light on questions that seem to be inaccessible using their semisimple relatives. In order to have potential applications to physics, these non-semisimple categories and TQFTs should possess Hermitian structures. We will define these structures and give some applications.
- - - - Thursday, Feb 23, 2023 - - - -
- - - - Friday, Feb 24, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Friday February 24, 2:00pm-3:30pm, Room 6417
Johanna Franklin, Hofstra University
When Gromov asked 'What is a typical group?', he was thinking of finitely presented groups, and he proposed an approach involving limiting density. Here, we reframe this question in the context of universal algebra and discuss some examples illustrating the behaviors of some of these algebraic varieties and then general conditions that imply some of these behaviors. Our primary general result states that for a commutative generalized bijective variety and presentations with a single generator and single identity, the zero-one law holds and, furthermore, that the sentences with density 1 are those true in the free structure. The proof of this result requires a specialized version of Gaifman's Locality Theorem that enables us to get a better bound on the complexity of the formulas of interest to us.
This work is joint with Meng-Che 'Turbo' Ho and Julia Knight.
Next Week in Logic at CUNY:
- - - - Monday, Feb 27, 2023 - - - -
Logic and Metaphysics Workshop
Date: Monday, February 27, 4.15-6.15pm (NY time), GC room TBD
NOTE: Meetings this semester are in person only (no zoom)
For meeting information, please sign up for our mailing list at
https://logic.commons.gc.cuny.edu/about/Lionel Shapiro, UConn
- - - - Tuesday, Feb 28, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 28, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Zuzana Hanikova, Czech Academy of Sciences
Vopěnka's Alternative Set Theory and its mathematical context
Vopěnka first presented his Alternative Set Theory (AST) in the monograph 'Mathematics in the Alternative Set Theory' published by Teubner, Leipzig in 1979. Another book presenting the theory, 'Introduction to Mathematics in the Alternative Set Theory', was published in 1989 in Slovak by Alfa, Bratislava. In addition there are numerous journal papers on the AST by members of the research group established by Vopěnka, and the proceedings of a conference dedicated to the AST, also from 1989. In several essays, Vopěnka sought to lay out the motivation and philosophical import of the AST and some of his subsequent work. As one consequence of the emphasis on his philosophy, the mathematical inspiration for the AST has been somewhat obliterated. The aim of the talk is to discuss the design choices Vopěnka made for the AST in relation to pertinent mathematical developments of the 20th century, such as Skolem's work on nonstandard models of arithmetic, Robinson's nonstandard analysis, Rieger's nonstandard models of arithmetic, Vopěnka's nonstandard model of set theory, Vopěnka and Hájek's theory of semisets, or Parikh's almost consistent theories. The presentation will include an outline of the AST following the works of Vopěnka and Sochor. This is a historical talk; no new mathematical results on the AST will be presented.
- - - - Wednesday, Mar 1, 2023 - - - -
- - - - Thursday, Mar 2, 2023 - - - -
- - - - Friday, Mar 3, 2023 - - - -
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
Wednesday seminar
Prague Set Theory Seminar
2/19/2023 10:44:12
Dear all,
The seminar meets on Wednesday February 22nd at 11:00 in the Institute
of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Jonathan Cancino Manriquez -- Maximal trees on P(omega)/fin
Given a partial order (P,<), a tree T on P is a subset of P such that T
order by the inverse order defined by <, is a tree. This notion was
introduced by D. Monk some years ago, and asked about the size of
maximal trees on [omega]^omega order by almost inclusion. In this talk
we will review some constructions of maximal trees of cardinality
omega_1 under some parametrized diamond principles and some related
results. This is joint work with G. Campero, M. Hrusak and F. Miranda.
Best,
David
Barcelona Set Theory Seminar
Barcelona Logic Seminar
2/18/2023 16:01:35
Dear All,
Please find attached the announcement of the next Barcelona Set Theory Seminar session.
SPEAKER: On Disjoint Stationary Sequences
DATE: Wednesday, 22 February 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:
Meeting ID: 985 6524 7347
Passcode: 243408
Best regards,
Joan
P.S.: If you do not wish to receive any more announcements, please send an email to
bagaria@ub.edu with the text “Unsubscribe”.
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Logic Seminar Wed 15 Feb 2023 17:00 hrs at NUS by David Belanger
NUS Logic Seminar
2/14/2023 18:19:12
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 15 February 2023, 17:00 hrs
Place: NUS, Department of Mathematics, S17#05-11
Speaker: David Belanger
Title: A system of functionals-of-finite-type for BSigma_n models
Abstract:
We present a system of functionals that can serve as Skolem functions,
so that any arithmetical formula can be rewritten in terms of them, in
a model of BSigma_n + not ISigma_n. A distinguishing feature of our
construction is that each functional is coded as a natural number
within the model, and there is an upper bound on the codes. The method
has a number of interesting applications.
This is joint work with Chong, Li, Wong and Yang.
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Nankai Logic Colloquium
Nankai Logic Colloquium
2/13/2023 5:42:19
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Riccardo Camerlo from University of Genoa. This talk is going to take place this Friday, Feb.17, 2023, from 4 pm to 5 pm (UTC+8, Beijing time).
Title: On some reducibility hierarchies
Abstract:
The notion of reducibility allows to compare sets or, more generally,
relations by using a given class of functions to make the comparison.
The choice of different classes of functions may give rise to very
diffent hierarchies.
Purpose of the talk is to give an elementary presentation of some of
these hierarchies, discuss some examples, and comment on some open
problems.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title: The 16th Nankai Logic Colloquium --Riccardo Camerlo
Time: 16:00pm, Feb. 17, 2023 (Beijing Time)
Zoom Number:839 6396 1742
Passcode: 321054
Link: https://zoom.us/j/83963961742?pwd=c2ppSXpMQks3Vit5bnZkUm5heElNUT09
_____________________________________________________________________
Best wishes,
Ming Xiao
This Week in Logic at CUNY
This Week in Logic at CUNY
2/12/2023 22:30:00
This Week in Logic at CUNY:
- - - - Monday, Feb 13, 2023 - - - -
Rutgers Logic Seminar
Monday, February 13, 2pm, Rutgers University, Hill 005
James Holland, Rutgers
Forcing more choice over the Chang model
- - - - Tuesday, Feb 14, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 14, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id) Vladimir Kanovei, Institute for Information Transmission Problems
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic
Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories. Given an axiom schema S, we let S* be the parameter-free sub-schema.
Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions. In particular, Kreisel noted that
[...] if one is convinced of the significance of something like a given axiom schema, it is natural to study details, such as the effect of parameters.This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.
- - - - Wednesday, Feb 15, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Second Lecture.
Speaker: Mee Seong Im, United States Naval Academy, Annapolis.
Date and Time: Wednesday February 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Automata and topological theories.
Abstract: Theory of regular languages and finite state automata is part of the foundations of computer science. Topological quantum field theories (TQFT) are a key structure in modern mathematical physics. We will interpret a nondeterministic automaton as a Boolean-valued one-dimensional TQFT with defects labelled by letters of the alphabet for the automaton. We will also describe how a pair of a regular language and a circular regular language gives rise to a lax one-dimensional TQFT.
- - - - Thursday, Feb 16, 2023 - - - -
- - - - Friday, Feb 17, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Friday February 17, 2:00pm-3:30pm, Room 6417
Russell Miller, CUNY
Computability and the Absolute Galois Group of Q
Fix a computable presentation ¯¯¯¯Q of the algebraic closure of the rational numbers. The absolute Galois group of the rational numbers, which is precisely the automorphism group of the field ¯¯¯¯Q, may then be viewed as a collection of paths through a finite-branching tree. Each individual automorphism has a Turing degree. We will use known results in computability to try to build natural countable elementary subgroups of the absolute Galois group. Several intriguing questions in number theory will appear as we measure the extent to which we succeed in doing so.
Next Week in Logic at CUNY:
- - - - Monday, Feb 20, 2023 - - - -
- - - - Tuesday, Feb 21, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 21, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Alexei Miasnikov, Stevens Institute of Technology
First-order classification and non-standard models
In this talk I will discuss some recent advances in the first-order classification problem. I will touch on first-order rigidity and quasi finite axiomatization. However, the main point of the presentation is on how, in principle, one can describe all structures which are first-order equivalent to a given one. This leads to non-standard models of algebraic structures (aka non-standard analysis or non-standard arithmetic), which are interesting in their own right.
- - - - Wednesday, Feb 22, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, Third Lecture.
Speaker: Joshua Sussan, CUNY.
Date and Time: Wednesday February 22, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Non-semisimple Hermitian TQFTs.
Abstract: Topological quantum field theories coming from semisimple categories build upon interesting structures in representation theory and have important applications in low dimensional topology and physics. The construction of non-semisimple TQFTs is more recent and they shed new light on questions that seem to be inaccessible using their semisimple relatives. In order to have potential applications to physics, these non-semisimple categories and TQFTs should possess Hermitian structures. We will define these structures and give some applications.
- - - - Thursday, Feb 23, 2023 - - - -
- - - - Friday, Feb 24, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Friday February 24, 2:00pm-3:30pm, Room 6417
Johanna Franklin, Hofstra University
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
Wednesday seminar
Prague Set Theory Seminar
2/12/2023 14:15:49
Dear all,
The seminar meets on Wednesday February 15th at 11:00 in the Institute
of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Chris Lambie-Hanson -- Whitehead's problem, expanded and
condensed, Part 2
Whitehead's problem, which asks whether every Whitehead group is a free
abelian group, was a prominent open question in group theory in the
mid-20th century. In 1974, Shelah proved that the problem is independent
of ZFC: if V=L, then every Whitehead group is free, whereas if Martin's
Axiom and the negation of CH hold, then there is a non-free Whitehead
group. This was a major surprise and was one of the first major problems
coming from outside logic and set theory to be proven to be independent.
Last week, we sketched a proof of Shelah's independence result. This
week, we present some more recent work, focusing on the category of
condensed abelian groups, introduced recently by Clausen and Scholze as
an enrichment of the category of topological abelian groups with nicer
algebraic properties. We will give a new, concrete, combinatorial proof
of a result, due to Clausen and Scholze, stating that Whitehead's
problem is not independent in the category of condensed abelian groups.
We will end by using some of the ideas of this proof to highlight some
potential connections between condensed mathematics and the theory of
forcing.
Best,
David
Barcelona Set Theory Seminar
Barcelona Logic Seminar
2/8/2023 3:52:44
Dear All,
Please find attached the announcement of the next Barcelona Set Theory Seminar session.
SPEAKER: Andreas Lietz
TITLE: Forcing "NS is
1-Dense"
from Large Cardinals
DATE: Wednesday, 15 February 2023
TIME: 16:00 (CET)
PLACE: Room B1 (UB). The Seminar can also be followed online via Zoom:
Meeting ID: 985 6524 7347
Passcode: 243408
Best regards,
Joan
P.S.: If you do not wish to receive any more announcements, please send an email to
bagaria@ub.edu with the text “Unsubscribe”.
Joan Bagaria
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Nankai Logic Colloquium
Nankai Logic Colloquium
2/8/2023 3:47:59
Hello everyone,
This week our weekly Nankai Logic Colloquium is going to be in the afternoon.
Our speaker this week will be Anush Tserunyan from McGill University. This talk is going to take place this Friday, Feb.10, 2023, from 4 pm to 5 pm (UTC+8, Beijing time).
Title. A descriptive approach to pointwise ergodic theorems
Abstract. Pointwise ergodic theorems provide a bridge between the global behaviour of the dynamical system and the local combinatorial statistics of the system at a point. These theorems are powerful tools used in ergodic theory, probability, number theory, and other areas of mathematics. I will describe a new general yet elementary approach for proving such theorems, which is inspired by descriptive set theory. This approach has led to new kinds of pointwise ergodic theorems, and I will discuss those obtained in joint work with Jenna Zomback.
___________________________________________________________________________________________________________________________________________________
This is going to be an online event. Follow the link below to join the Zoom meeting. Please use your real name to join the meeting.
Title: The 15th Nankai Logic Colloquium --Anush Tserunyan
Time: 16:00pm, Feb. 10, 2023 (Beijing Time)
Zoom Number:836 2979 3119
Passcode: 476294
Link: https://us02web.zoom.us/j/83629793119?pwd=R1c4OHJReXNMTHE2dFpOOS91bnhQUT09
_____________________________________________________________________
Best wishes,
Ming Xiao
Logic Seminar Wed 8 Feb 2023 17:00 hrs at NUS via Zoom by Will Johnson
NUS Logic Seminar
2/6/2023 21:16:09
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 8 February 2023, 17:00 hrs
Talk via Zoom:
https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
Meeting ID: 830 4925 8042
Passcode: 1729=x3+y3
Speaker: Will Johnson
Title: NIP integral domains and Henselianity
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Abstract:
Is every NIP integral domain a Henselian local ring?
In this talk, I will give evidence for this conjecture,
sketching why it holds in the positive characteristic
case and the finite dp-rank case. I will also discuss
how this ``generalized Henselianity conjecture''
is related to the standard conjectures on NIP fields
and valued fields. For example, the Henselianity
conjecture for NIP valued fields implies the
generalized Henselianity conjecture for Noetherian NIP
integral domains.
Lastly I will discuss how this conjecture fits
into the general problem of classifying NIP fields
and NIP commutative rings. For example, it implies
that NIP fields with definable field topologies
must be ample/large in the sense of Pop, and
NIP commutative rings must be finite products
of Henselian local rings.
UPDATE: This Week in Logic at CUNY
This Week in Logic at CUNY
2/6/2023 10:18:34
Hi everyone,
Note the updated email for Victoria Gitman throughout the newsletter below - please use her updated address
vgitman@gmail.com.
Best,
Jonas
This Week in Logic at CUNY:
- - - - Monday, Feb 6, 2023 - - - -
Rutgers Logic Seminar
Monday, February 6, 2pm, Rutgers University, Hill 005
Brian Pinsky, Rutgers
Hopfian groups are complete co-analytic
- - - - Tuesday, Feb 7, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 7, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id)Mikhail Katz, Bar Ilan University
Effective infinitesimals in R
We survey the effective foundations for analysis with infinitesimals recently developed by Hrbacek and Katz, and detail some applications. Theories SPOT and SCOT illustrate the fact that analysis with infinitesimals requires no more choice than traditional analysis. The theory SCOT incorporates in particular all the axioms of Nelson's Radically Elementary Probability Theory, which is therefore conservative over ZF+ADC.
- - - - Wednesday, Feb 8, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, First Lecture.
Speaker: Mikhail Khovanov, Columbia University.
Date and Time: Wednesday February 8, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Universal construction and its applications.
Abstract: Universal construction starts with an evaluation of closed n-manifolds and builds a topological theory (a lax TQFT) for n-cobordisms. A version of it has been used for years as an intermediate step in constructing link homology theories, by evaluating foams embedded in 3-space. More recently, universal construction in low dimensions has been used to find interesting structures related to Deligne categories, formal languages and automata. In the talk we will describe the universal construction and review these developments.
- - - - Thursday, Feb 9, 2023 - - - -
- - - - Friday, Feb 10, 2023 - - - -
Set Theory SeminarCUNY Graduate Center, Friday, February 10, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@gmail.com) for meeting id. Davide Leonessi CUNY
Strategy and determinacy in infinite Hex
The popular game of Hex can be extended to the infinite hexagonal lattice, defining a winning condition which formalises the idea of a chain of colored stones stretching towards infinity. The descriptive-set-theoretic complexity of the set of winning positions is unknown, although it is at most Σ^1_1, and it is conjectured to be Borel; this has implications on whether games of infinite Hex are determined from all initial positions as either first-player wins or draws.
I will show that, unlike the finite game, infinite Hex with an initially empty board is a draw. But is the game still a draw when starting from a non-empty board? This open question can be partially answered in the positive by assuming the existence of certain local strategies, and in the negative by giving the advantage of placing two stones at each turn to one of the players. This is joint work with Joel David Hamkins.
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Friday February 10, 2:00pm-3:30pm, Room 6417
Athar Abdul-Quader, Purchase College
Satisfaction and saturation
It is well known that a countable model of PA has a truth predicate if and only if it is recursively saturated. It is also well known that not all countable recursively saturated models of PA have *inductive* or even Δ0-inductive truth predicates: indeed, such models must satisfy Con(PA), for example. Recent work by Enayat-Pakhomov and Cieśliński-Łełyk-Wcisło explored the principle of 'disjunctive correctness', asserting that every disjunction is true if and only if it has a true disjunct. In particular, one can show that every countable model of PA has a 'disjunctively trivial' elementary extension: that is, an elementary extension with a truth predicate in which all nonstandard length disjunctions are evaluated as true. In this talk, we will see that such 'disjunctively trivial' models are necessarily arithmetically saturated; indeed, we will see that a countable model of PA is arithmetically saturated if and only if it has a disjunctively trivial truth predicate. We will explore related pathologies in truth predicates, and classify the sets which can be defined using such pathologies. We find other surprising connections between arithmetic saturation and these questions of definability. This is joint work with Mateusz Łełyk, based heavily on unpublished work by Jim Schmerl.
Next Week in Logic at CUNY:
- - - - Monday, Feb 13, 2023 - - - -
Rutgers Logic Seminar
Monday, February 13, 2pm, Rutgers University, Hill 005
James Holland, Rutgers
- - - - Tuesday, Feb 14, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 14, 1:00pmVirtual (email Victoria Gitman vgitman@gmail.com for meeting id) Vladimir Kanovei, Institute for Information Transmission Problems
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic
Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories. Given an axiom schema S, we let S* be the parameter-free sub-schema.
Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions. In particular, Kreisel noted that
[...] if one is convinced of the significance of something like a given axiom schema, it is natural to study details, such as the effect of parameters.This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.
- - - - Wednesday, Feb 15, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, First Lecture.
Speaker: Mee Seong Im, United States Naval Academy, Annapolis.
Date and Time: Wednesday February 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Automata and topological theories.
Abstract: Theory of regular languages and finite state automata is part of the foundations of computer science. Topological quantum field theories (TQFT) are a key structure in modern mathematical physics. We will interpret a nondeterministic automaton as a Boolean-valued one-dimensional TQFT with defects labelled by letters of the alphabet for the automaton. We will also describe how a pair of a regular language and a circular regular language gives rise to a lax one-dimensional TQFT.
- - - - Thursday, Feb 16, 2023 - - - -
- - - - Friday, Feb 17, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@gmail.com) for meeting id.
Friday February 17, 2:00pm-3:30pm, Room 6417
Russell Miller, CUNY
Computability and the Absolute Galois Group of Q
Fix a computable presentation ¯¯¯¯Q of the algebraic closure of the rational numbers. The absolute Galois group of the rational numbers, which is precisely the automorphism group of the field ¯¯¯¯Q, may then be viewed as a collection of paths through a finite-branching tree. Each individual automorphism has a Turing degree. We will use known results in computability to try to build natural countable elementary subgroups of the absolute Galois group. Several intriguing questions in number theory will appear as we measure the extent to which we succeed in doing so.
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
This Week in Logic at CUNY
This Week in Logic at CUNY
2/5/2023 22:30:00
This Week in Logic at CUNY:
- - - - Monday, Feb 6, 2023 - - - -
Rutgers Logic Seminar
Monday, February 6, 2pm, Rutgers University, Hill 005
Brian Pinsky, Rutgers
Hopfian groups are complete co-analytic
- - - - Tuesday, Feb 7, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 7, 1:00pmVirtual (email Victoria Gitman vgitman@nylogic.org for meeting id)Mikhail Katz, Bar Ilan University
Effective infinitesimals in R
We survey the effective foundations for analysis with infinitesimals recently developed by Hrbacek and Katz, and detail some applications. Theories SPOT and SCOT illustrate the fact that analysis with infinitesimals requires no more choice than traditional analysis. The theory SCOT incorporates in particular all the axioms of Nelson's Radically Elementary Probability Theory, which is therefore conservative over ZF+ADC.
- - - - Wednesday, Feb 8, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, First Lecture.
Speaker: Mikhail Khovanov, Columbia University.
Date and Time: Wednesday February 8, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Universal construction and its applications.
Abstract: Universal construction starts with an evaluation of closed n-manifolds and builds a topological theory (a lax TQFT) for n-cobordisms. A version of it has been used for years as an intermediate step in constructing link homology theories, by evaluating foams embedded in 3-space. More recently, universal construction in low dimensions has been used to find interesting structures related to Deligne categories, formal languages and automata. In the talk we will describe the universal construction and review these developments.
- - - - Thursday, Feb 9, 2023 - - - -
- - - - Friday, Feb 10, 2023 - - - -
Set Theory SeminarCUNY Graduate Center, Friday, February 10, 12:15pm NY timeVirtual: Please email Victoria Gitman (vgitman@nylogic.org) for meeting id. Davide Leonessi CUNY
Strategy and determinacy in infinite Hex
The popular game of Hex can be extended to the infinite hexagonal lattice, defining a winning condition which formalises the idea of a chain of colored stones stretching towards infinity. The descriptive-set-theoretic complexity of the set of winning positions is unknown, although it is at most Σ^1_1, and it is conjectured to be Borel; this has implications on whether games of infinite Hex are determined from all initial positions as either first-player wins or draws.
I will show that, unlike the finite game, infinite Hex with an initially empty board is a draw. But is the game still a draw when starting from a non-empty board? This open question can be partially answered in the positive by assuming the existence of certain local strategies, and in the negative by giving the advantage of placing two stones at each turn to one of the players. This is joint work with Joel David Hamkins.
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@nylogic.org) for meeting id.
Friday February 10, 2:00pm-3:30pm, Room 6417
Athar Abdul-Quader, Purchase College
Satisfaction and saturation
It is well known that a countable model of PA has a truth predicate if and only if it is recursively saturated. It is also well known that not all countable recursively saturated models of PA have *inductive* or even Δ0-inductive truth predicates: indeed, such models must satisfy Con(PA), for example. Recent work by Enayat-Pakhomov and Cieśliński-Łełyk-Wcisło explored the principle of 'disjunctive correctness', asserting that every disjunction is true if and only if it has a true disjunct. In particular, one can show that every countable model of PA has a 'disjunctively trivial' elementary extension: that is, an elementary extension with a truth predicate in which all nonstandard length disjunctions are evaluated as true. In this talk, we will see that such 'disjunctively trivial' models are necessarily arithmetically saturated; indeed, we will see that a countable model of PA is arithmetically saturated if and only if it has a disjunctively trivial truth predicate. We will explore related pathologies in truth predicates, and classify the sets which can be defined using such pathologies. We find other surprising connections between arithmetic saturation and these questions of definability. This is joint work with Mateusz Łełyk, based heavily on unpublished work by Jim Schmerl.
Next Week in Logic at CUNY:
- - - - Monday, Feb 13, 2023 - - - -
Rutgers Logic Seminar
Monday, February 13, 2pm, Rutgers University, Hill 005
James Holland, Rutgers
- - - - Tuesday, Feb 14, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, February 14, 1:00pmVirtual (email Victoria Gitman vgitman@nylogic.org for meeting id)Vladimir Kanovei, Institute for Information Transmission Problems
On the significance of parameters in the choice and сomprehension schemata in the 2nd-order Peano arithmetic
Parameters are free variables in various axiom schemata in PA, ZFC, and other similar theories. Given an axiom schema S, we let S* be the parameter-free sub-schema.
Kreisel (A survey of proof theory, JSL 1968) was one of those who paid attention to the comparison of some schemata in second-order PA and their parameter-free versions. In particular, Kreisel noted that
[...] if one is convinced of the significance of something like a given axiom schema, it is natural to study details, such as the effect of parameters.This talk is devoted to the effect of parameters in the schemata of Comprehension and Choice in second-order arithmetic.
- - - - Wednesday, Feb 15, 2023 - - - -
The New York City Category Theory Seminar
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
Special Topic: TQFT and Computation, First Lecture.
Speaker: Mee Seong Im, United States Naval Academy, Annapolis.
Date and Time: Wednesday February 15, 2023, 7:00 - 8:30 PM. IN PERSON TALK.
Title: Automata and topological theories.
Abstract: Theory of regular languages and finite state automata is part of the foundations of computer science. Topological quantum field theories (TQFT) are a key structure in modern mathematical physics. We will interpret a nondeterministic automaton as a Boolean-valued one-dimensional TQFT with defects labelled by letters of the alphabet for the automaton. We will also describe how a pair of a regular language and a circular regular language gives rise to a lax one-dimensional TQFT.
- - - - Thursday, Feb 16, 2023 - - - -
- - - - Friday, Feb 17, 2023 - - - -
Logic Workshop
CUNY Graduate Center
Hybrid: Please email Victoria Gitman (
vgitman@nylogic.org) for meeting id.
Friday February 17, 2:00pm-3:30pm, Room 6417
Russell Miller, CUNY
Computability and the Absolute Galois Group of Q
Fix a computable presentation ¯¯¯¯Q of the algebraic closure of the rational numbers. The absolute Galois group of the rational numbers, which is precisely the automorphism group of the field ¯¯¯¯Q, may then be viewed as a collection of paths through a finite-branching tree. Each individual automorphism has a Turing degree. We will use known results in computability to try to build natural countable elementary subgroups of the absolute Galois group. Several intriguing questions in number theory will appear as we measure the extent to which we succeed in doing so.
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
Wednesday seminar
Prague Set Theory Seminar
2/4/2023 7:24:17
Dear all,
The seminar meets on Wednesday February 8th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Chris Lambie-Hanson -- Whitehead's problem, expanded and condensed
Whitehead's problem, which asks whether every Whitehead group is a free
abelian group, was a prominent open question in group theory in the
mid-20th century. In 1974, Shelah proved that the problem is independent
of ZFC: if V=L, then every Whitehead group is free, whereas if Martin's
Axiom and the negation of CH hold, then there is a non-free Whitehead
group. This was a major surprise and was one of the first major problems
coming from outside logic and set theory to be proven to be independent.
In recent years, Clausen and Scholze have introduced the category of
condensed abelian groups, which can be seen as an enrichment of the
category of topological abelian groups with nicer algebraic properties.
Through some deep structural analysis of this category, they showed
that, when appropriately interpreted, Whitehead's problem is not
independent in the category of condensed abelian groups; it is provable
in ZFC that every abelian group that is Whitehead in the condensed
category must be free. In the first half of the talk, we will introduce
Whitehead's problem and provide a sketch of Shelah's proof. In the
second half, we will give a new, concrete, combinatorial proof of
Clausen and Scholze's result. No knowledge of algebra will be assumed of
the audience; all proofs will involve only set theoretic techniques and
very basic group theory.
Best,
David
Core model seminar next Tuesday
Carnegie Mellon Logic Seminar
2/2/2023 10:16:42
ABSTRACT: We discuss the inner model C(aa) introduced by Kennedy-Magidor-Väänänen, and answer several questions posed in their paper "Inner models from strong logics". Assuming large cardinal axioms, we'll show that this model satisfies GCH (this is joint work with John Steel) and that C(aa) satisfies o(κ) = κ++ for all regular cardinals κ > ω1 (this is joint work with Otto Rajala).
CMU math logic seminar next Tuesday
Carnegie Mellon Logic Seminar
2/2/2023 10:12:06
TUESDAY, February 7, 2023
Mathematical Logic Seminar: 3:30-4:30 PM Eastern,
Online, Tom Benhamou, University of Illinois at Chicago
Join Zoom Meeting:
https://cmu.zoom.us/j/92655324096?pwd=VUhSSlkrdHMxbTlSYUMxYzFXM01kdz09Meeting ID: 926 5532 4096
Passcode: 555455
TITLE: Saturation properties of ultrafilters
ABSTRACT: In this talk, we will focus on certain saturation properties of filters and ultrafilters which generalizes the so-called Galvin property. In the first part of the talk, we will present a connection between such ultrafilters and the existence of Slim-Kurepa trees. We will then present several results regarding the existence of non-Galvin ultrafilters under several large cardinal assumptions. Finally, if time permits, we will present a recent application to canonical inner models and some open related questions.
Logic Seminar 1 Feb 2023 17:00 hrs at NUS by Yu Liang, Nanjing University
NUS Logic Seminar
1/27/2023 0:29:50
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 1 February 2023, 17:00 hrs
Place: NUS, Department of Mathematics, S17#05-11
Speaker: Yu Liang
Title: Some applications of recursion theory to set theory
Abstract: I shall present some recent results in set theory
which are based on proof methods and results from recursion theory.
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
Reminder for today's Talk
NUS Logic Seminar
1/25/2023 3:49:53
The following logic semianr talk is today (now) at 17:00 hrs
Singapore time; the talk is only by Zoom.
The Zoom Login is this:
https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
Meeting ID: 830 4925 8042
Passcode: 1729=x3+y3
Title and Abstract of today's talk can be found on the
following webpage of the logic seminar:
https://www.comp.nus.edu.sg/~fstephan/logicseminar.html
The title is: Regressive versions of Hindman's Theorem.
The speaker is: Leonardo Mainardi.
You find on this link also the still free time-slots; if any of
you wants to give a talk from overseas, we will make it on Zoom
as well; local speakers can also give a physical talk in the
meeting.
Best regards, Frank
Cross-Alps Logic Seminar (speaker: Katarzyna Kowalik)
Cross-Alps Logic Seminar
1/23/2023 4:58:04
On Friday 27.01.2023 at 16:00
Katarzyna Kowalik (University of Warsaw)will give a talk on
Reverse mathematics of some Ramsey-theoretic principles over a weak base theoryPlease refer to the usual webpage of our
LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
This Week in Logic at CUNY
This Week in Logic at CUNY
1/22/2023 22:30:00
The CUNY semester starts this week - welcome back, everyone! I want to draw particular attention to the Fitting at 80 Conference taking place this Saturday, January 28th (see below for details).
Best,
Jonas Reitz
This Week in Logic at CUNY:
- - - - Monday, Jan 23, 2023 - - - -
Rutgers Logic Seminar
Monday, January 23, 2pm, Rutgers University, Hill 005
Chris Laskowski (University of Maryland)
The Borel complexity of modules
- - - - Tuesday, Jan 24, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, January 24, 1:00pmVirtual (email Victoria Gitman vgitman@nylogic.org for meeting id)Karel Hrbacek, CUNY
Representation of unlimited integers
Nonstandard methods have been successfully applied to standard problems in number theory by R. Jin, T. Tao and others. A. Boudaoud and D. Bellaouar are pursuing the opposite direction: they are formulating number-theoretic problems in the language of nonstandard analysis and solving them by standard methods. Two examples of the kind of questions they consider are:
(1) Can every unlimited natural number n be represented in the form n = s + w_1w_2 where s is a limited integer and w_1, w_2 are unlimited?
(2) Can every unlimited natural number n be represented in the form n = w_1w_2 + w_3w_4 so that each ratio w_i / w_j is appreciable (ie, neither infinitesimal nor unlimited)?
I give a negative answer to question (1) (assuming Dickson’s Conjecture) and a positive answer to question (2).
A. Boudaoud, D. Bellaouar, Representation of integers: A nonclassical point of view, Journal of Logic & Analysis. 12:4 (2020) 1{31; K. Hrbacek, Journal of Logic & Analysis 12:5 (2020) 1–6.
- - - - Wednesday, Jan 25, 2023 - - - -
- - - - Thursday, Jan 26, 2023 - - - -
- - - - Friday, Jan 27, 2023 - - - -
- - - - Saturday, Jan 28, 2023 - - - -
Fitting at 80Saturday, January 28
A prominent logician Melvin Fitting has turned 80. This online conference is a special event in his honor. Melvin Fitting was in the departments of Computer Science, Philosophy, and Mathematics at the CUNY Graduate Center and in the department of Mathematics and Computer Science at Lehman College. He is now Professor Emeritus. He has authored 11 books and over a hundred research papers with staggering citation figures. In 2012 Melvin Fitting was given the Herbrand Award by the Conference on Automated Deduction (CADE) for distinguished contributions to the field.
Greetings, congratulations, photos for posting, and ZOOM link requests could be sent to Sergei Artemov by
sartemov@gmail.com or
sartemov@gc.cuny.edu.
Conference website
https://sartemov.ws.gc.cuny.edu/fitting-at-80/Program (the times are given in the Eastern Day Time zone EST).
January 28, Saturday
8:00-8:45 am Arnon Avron (Tel Aviv), “Breaking the Tie: Benacerraf’s Identification Argument Revisited”
8:45-9:30 am Junhua Yu (Beijing), "Exploring Operators on Neighborhood Models"
9:45-10:30 am Sara Negri (Genoa), "Faithful Modal Embedding: From Gödel to Labelled Calculi"
10:30-11:15 am Heinrich Wansing (Bochum), “Remarks on Semantic Information and Logic. From Semantic Tetralateralism to the Pentalattice 65536_5”
11:30 am -12:15 pm Roman Kuznets (Vienna), "On Interpolation"
12:15-1:00 pm Walter Carnielli (Campinas), “Combining KX4 and S4: A Logic That Encompasses Factive and Non-factive Evidence”
1:15-2:00 pm Eduardo Barrio and Federico Pailos (Buenos Aires), “Meta-classical Non-classical Logics”
2:00-2:45 pm Graham Priest (New York), "Jaśkowski and the Jains: a Fitting Tribute"
2:45-4:00 pm Session of memories and congratulations featuring Sergei Artemov, Hiroakira Ono, Anil Nerode, Melvin Fitting, and others.
Next Week in Logic at CUNY:
- - - - Monday, Jan 30, 2023 - - - -
- - - - Tuesday, Jan 31, 2023 - - - -
Models of Peano Arithmetic (MOPA)Tuesday, January 31, 1:00pmVirtual (email Victoria Gitman vgitman@nylogic.org for meeting id)Lorenzo Galeotti, Amsterdam University College
Order types of models of arithmetic without induction
It is a well-known fact that non-standard models of Peano Arithmetic (PA) have order type N + Z · D, where D is a dense linear order. The question of which dense linear orders D can occur in such order types is non-trivial and widely studied. In this context Friedman asked the following question:
Are there consistent extensions of Peano Arithmetic T and T′ such that the class of order types of models of T and the class of order types of models of T′ differ?
Friedman’s question is very complex and still wide open. In this talk we will go in the opposite direction and consider a version of Friedman’s question for syntactic fragments of PA. We will present results from a joint work with Benedikt Löwe on order types of non-standard models of syntactic subsystems of arithmetic obtained by restricting the language to subsets of the operations. We will put particular emphasis on models of syntactic subsystems of Peano Arithmetic obtained by dropping the schema of induction.
- - - - Wednesday, Feb 1, 2023 - - - -
- - - - Thursday, Feb 2, 2023 - - - -
- - - - Friday, Feb 3, 2023 - - - -
Set Theory SeminarCUNY Graduate Center, Friday, February 3, 12:30pm NY timeVirtual: Please email Victoria Gitman (vgitman@nylogic.org) for meeting id. Jing Zhang, University of Toronto
- - - - Other Logic News - - - -- - - - Web Site - - - -Find us on the web at: nylogic.github.io(site designed, built & maintained by Victoria Gitman)-------- ADMINISTRIVIA --------To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.If you have a logic-related event that you would like included in future mailings, please email jreitz@nylogic.org.
Wednesday seminar
Prague Set Theory Seminar
1/22/2023 17:07:37
Dear all,
The seminar meets on Wednesday January 25th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: David Bradley-Williams -- Limits of betweenness relations and
their automorphism groups
Some permutation groups are best represented/constructed as
kinds-of-products of or limits of simpler permutation groups. We discuss
joint work with John Truss (Leeds) in which we construct a family of
structures called "limits of betweenness relations" as a kind of
tree-limit of trees (for appropriate combinatorial meanings of the word
"tree"). A crucial part of the construction is an particular instance of
categorical Fraissé Theory. Further we plan to say how their
automorphism groups fit into the landscape of infinite primitive Jordan
permutation groups and the structure theory of Jordan groups established
by S. Adeleke, D. Macpherson, and P. M. Neumann.
Best,
David
PS: Let me also remind you the joint Logic Seminar/Colloquium of the
MLTCS department on Monday January 23rd, 16:00, Institute of Mathematics
CAS, blue lecture room on the ground floor of the rear building. After
the lecture we will go to a pub.
Niel Thapen -- Bounded arithmetic and witnessing
A witnessing theorem lets you recover, from a proof that an object
exists, an algorithm to construct such an object. I will introduce the
weak arithmetic theory S^1_2 and describe a simple model-theoretic proof
of Buss's witnessing theorem, connecting this theory with polynomial
time computations, with some unprovability results that follow from
this. I will discuss some open problems about witnessing for stronger
bounded theories.
(KGRC) guests, video, and a talk on Thursday, January 26
Kurt Godel Research Center
1/19/2023 12:21:04
The KGRC welcomes as guests:
Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31 and
gives a talk on January 26, see below.
Franz-Viktor Kuhlmann (host: Matthias Aschenbrenner) visits the KGRC until
January 31.
Jonathan Schilhan (host: Thilo Weinert) visits the KGRC until January 31.
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15.
Jerzy Kąkol (host: Damian Sobota) visits the KGRC from February 27 to March 3.
Manuel López Pellicer (host: Damian Sobota) visits the KGRC from February 27 to
March 3.
Juris Steprāns (host: Vera Fischer) visits the KGRC from March 6 to March 10
and gives a two-part talk, details to be announced at a later time.
* * *
For some seminar talks, video recordings are available:
"Introduction to big Ramsey degrees" by David Chodounský:
https://univienna.zoom.us/rec/share/he-aDDiZDHZJ8Y4Zn_FjiIwdbOf0VN6UKJrxWC7xXAEf6CG_k6Cu_QfM3gQGzwsd.wYq8tUjxaZFywaFK
Pass code: @&61nNnR
"The weak Ramsey property" by Wiesław Kubiś:
https://univienna.zoom.us/rec/share/VeLRgmK7tBdTUOLxgzKjPhh20ErRsjUWp7v6hkNpZtM9Gxe3Xu73_Cc_iTF_AYpL.zDpkipMb7P_vKHwO
Pass code: +MkI4HUc
"A weak form of Global Choice under the GCH, part II" by Peter Holy:
https://univienna.zoom.us/rec/share/xVaRaaDknVfPsyI6D_XZtFsxMjHr8bYSXbup0r6knM3oojoSAFdjipHgPOzN5jVw.8N-UyUkiL2g_6IJj
Pass code: gS3%+Hy2
* * *
Logic Colloquium
Kurt Gödel Research Center
Thursday, January 26
"Lang-Weil type bounds in finite difference fields"
Martin Hils (Universität Münster, DE)
We establish Lang-Weil type bounds for the number of rational points of
difference varieties over finite difference fields, in terms of the transformal
dimension of the variety and assuming the existence of a smooth rational point.
It follows that, working in any non-principle ultraproduct $K$ of finite
difference fields, the normalized pseudofinite dimension of a quantifier free
partial type $p$ is equal to the transformal dimension of $p$, i.e., to the
maximal transformal transcendence degree over $K$ of a realization of $p$.
This is joint work with Ehud Hrushovski, Jinhe Ye and Tingxiang Zou.
Time and Place
Talk at 3:00pm in hybrid mode, in person as well as via Zoom. (Students at Uni
Wien are required to attend in person.)
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom: If you need the Zoom data and have not received the meeting link by
the day before the talk, please contact richard.springer@univie.ac.at!
(Please direct any other requests about the Zoom session to
vera.fischer@univie.ac.at.)
Logic Seminar Wed 18 Jan 2023 17:00 hrs at NUS by Bakhadyr Khoussainov
NUS Logic Seminar
1/18/2023 4:12:18
Hello, there was a mistake, the talk is only in Zoom.
Please use this login (also below):
> > Link to join the Zoom Meeting
> > https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
> >
> > Meeting ID: 830 4925 8042
> > Passcode: 1729=x3+y3
Sorry for the confusion caused. Regards, Frank Stephan
On Thu, Jan 12, 2023 at 03:01:35PM +0800, Frank STEPHAN wrote:
> Invitation to the Logic Seminar at the National University of Singapore
>
> Date: Wednesday, 18 January 2022, 17:00 hrs
>
> Place: NUS, Department of Mathematics, S17#04-05
> Talk via Zoom:
> https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
> Meeting ID: 830 4925 8042
> Passcode: 1729=x3+y3
>
> Speaker: Bakhadyr Khoussainov
>
> Title: Definability of algorithmically presented structures.
>
> URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
>
> We aim to describe the isomorphism types of algorithmically
> presented structures in the language of the first order logic.
> This is one of the key research topics related to the expressive
> power of the first order logic. The focus is on two classes
> of structures. The first class is the class of structures for
> which the positive atomic diagrams are computably enumerable.
> We call these structures positive structures. The second class
> is the class of structures for which the negative atomic diagrams
> are computably enumerable. We call these structures negative
> structures. We investigate definability of positive and negative
> structures by sets of sentences quantified with Existential,
> Universal, Existential-Universal and Universal-Existential
> quantifiers using expansions of languages.
>
Descriptive Set Theory and Dynamics: Warsaw, Poland, August 14-25, 2023
Conference
1/17/2023 20:37:12
In August 2023 a workshop and a conference on descriptive set theory and dynamics will take place in Warsaw:
Workshop (14-18.08.2023, Warsaw)
Conference (21-25.08.2023, Warsaw)
Both are organized within the thematic semester STRUCTURES devoted to various areas of foundations of mathematics and computer science
https://www.impan.pl/en/activities/banach-center/conferences/23-simons-08
Tagged: Dana Bartošová, Anton Bernshteyn, Filippo Calderoni, Ruiyuan Chen, Michal Doucha, Joshua Frish, Su Gao, Łukasz Grabowski, Jan Grebík, Alexander Kechris, Gábor Kun, Aleksandra Kwiatkowska, François Le Maître, Aristotelis Panagiotopoulos, Oleg Pikhurko, Assaf Shani, Konstantin Slutsky, Sławomir Solecki, Ádám Timár, Todor Tsankov, Spencer Unger, Zoltán Vidnyánszky, Andrew Zucker, Matthew Foreman, Yonatan Gutman, Todor Tsankov, Anush Tserunyan, Shaun Allison, Matthew Bowen, Colin Jahel, Forte Shinko, Grigory Terlov, Riley Thornton, Felix Weilacher, Konrad Wrobel
CMU Math Logic Seminar next Tuesday
Carnegie Mellon Logic Seminar
1/17/2023 12:37:12
TUESDAY, January 24, 2023
Mathematical Logic Seminar: 3:30-4:30 PM Eastern, Online, Paolo Marimon,
Imperial College London
Join Zoom Meeting:
https://cmu.zoom.us/j/92655324096?pwd=VUhSSlkrdHMxbTlSYUMxYzFXM01kdz09
Meeting ID: 926 5532 4096
Passcode: 555455
TITLE: Invariant Keisler measures in simple omega-categorical structures
ABSTRACT: We study invariant Keisler measures in the context of
omega-categorical structures. For a first-order structure M, these are
finitely additive probability measures on the Boolean algebra of definable
subsets Def_x(M) which are invariant under the action of the automorphism
group Aut(M). A natural notion of smallness for a definable subset of M is
that it is assigned measure 0 by any invariant Keisler measure. Another
natural model-theoretic notion of smallness is forking over the empty set.
These two notions coincide in various classes of structures, including
stable and NIP omega-categorical ones. In a recent article, Chernikov,
Hrushovski, Kruckman, Krupinski, Moconja, Pillay and Ramsey find the first
examples of simple structures with formulas which do not fork over the
empty set but are universally measure zero. I give the first known simple
omega-categorical examples exhibiting this property. These are various
omega-categorical Hrushovski constructions. In order to prove this, I use
a probabilistic independence result by Jahel and Tsankov to show that a
stronger version of the independence theorem holds for simple
omega-categorical structures where a formula forks over the empty set if
and only if it is universally measure zero.
Wednesday seminar
Prague Set Theory Seminar
1/15/2023 16:33:35
Dear all,
The seminar meets on Wednesday January 18th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
There will be a joint Logic Seminar/Colloquium of the MLTCS department
on Monday January 23rd, 16:00, Institute of Mathematics CAS, blue
lecture room on the ground floor of the rear building. After the lecture
we will go to a pub. Everybody will be welcome!
Wednesday program:
Adam Bartoš -- Isosceles-free homogeneous metric spaces
While studying metric spaces in the context of Fraïssé theory we have
considered the class of isosceles-free metric spaces: the spaces
containing no nondegenerate isosceles triangles. All finite
isoceles-free spaces form a hereditary class without weak amalgamation
property. Every 1-homogeneous isosceles-free space is already
ultrahomogeneous, and we can characterize all such spaces. There are
also related decompositions of metric spaces giving bounds on the
maximal number of distinct distances in a finite ultrahomogeneous metric
space. This is joint work with Christian Bargetz, Wiesław Kubiś, and
Franz Luggin.
MLTCS seminar:
Niel Thapen -- Bounded arithmetic and witnessing
A witnessing theorem lets you recover, from a proof that an object
exists, an algorithm to construct such an object. I will introduce the
weak arithmetic theory S^1_2 and describe a simple model-theoretic proof
of Buss's witnessing theorem, connecting this theory with polynomial
time computations, with some unprovability results that follow from
this. I will discuss some open problems about witnessing for stronger
bounded theories.
Best,
David
(KGRC) Set Theory Seminar talk on Tuesday, January 17
Kurt Godel Research Center
1/13/2023 10:46:49
The KGRC welcomes as guests:
Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31, 2023
and gives a talk on January 26, 2023 (details to be announced at a later time).
Franz-Viktor Kuhlmann (host: Matthias Aschenbrenner) visits the KGRC until
January 31, 2023.
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August 15.
Tomasz Żuchowski (host: Damian Sobota) visits the KGRC until January 17.
Jerzy Kąkol (host: Damian Sobota) visits the KGRC from February 27 to March 3.
Manuel López Pellicer (host: Damian Sobota) visits the KGRC from February 27 to
March 3.
Juris Steprāns (host: Vera Fischer) visits the KGRC from March 6 to March 10
and gives a two-part talk (details to be announced at a later time).
* * *
Set Theory Research Seminar
Kurt Gödel Research Center
Tuesday, January 17
"A weak form of Global Choice under the GCH, part 2"
Peter Holy (TU Wien)
In 2012, Joel Hamkins asked (on MathOverflow) whether it is possible for the
universe of sets to have a linear ordering, but no wellordering (that is,
global choice fails). This question, which I consider very interesting, appears
to still be open. In my talk, I want to present a somewhat related result.
After providing a gentle introduction to second order set theory and the
principle of global choice (no knowledge on these matters is assumed), we
consider a different weakening of global choice under the GCH: The minimal
ordinal-connection axiom MOC due to Rodrigo Freire. It is equivalent to the
statement that the universe of sets can be stratified by a subset-increasing
hierarchy with each K_alpha of the same size as alpha,
and such that K_kappa=H(kappa), the collection of sets of hereditary size less
than kappa, for every regular infinite cardinal kappa. In this form, it clearly
implies the GCH, and is easily seen to be a weak form of global choice under
the GCH. We will show, using class forcing products of adding Cohen subsets of
regular cardinals (without assuming any particular knowledge regarding the
technique of class forcing), that MOC can consistently fail in models of the
GCH, and that MOC can consistently hold while global choice fails.
This is joint work with Rodrigo Freire (University of Brasilia).
Time and Place
Talk at 3:00pm in hybrid mode, in person as well as via Zoom. (Students at Uni
Wien are required to attend in person.)
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom:
If you need the Zoom data and have not received the meeting link by the
day before the talk, please contact richard.springer@univie.ac.at! (Please
direct any other requests about the Set Theory Seminar to
vera.fischer@univie.ac.at.)
Logic Seminar Wed 18 Jan 2023 17:00 hrs at NUS by Bakhadyr Khoussainov
NUS Logic Seminar
1/12/2023 2:01:35
Invitation to the Logic Seminar at the National University of Singapore
Date: Wednesday, 18 January 2022, 17:00 hrs
Place: NUS, Department of Mathematics, S17#04-05
Talk via Zoom:
https://nus-sg.zoom.us/j/83049258042?pwd=UWViaWNvTFUrdFdhOHJCdEVydnVkdz09
Meeting ID: 830 4925 8042
Passcode: 1729=x3+y3
Speaker: Bakhadyr Khoussainov
Title: Definability of algorithmically presented structures.
URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html
We aim to describe the isomorphism types of algorithmically
presented structures in the language of the first order logic.
This is one of the key research topics related to the expressive
power of the first order logic. The focus is on two classes
of structures. The first class is the class of structures for
which the positive atomic diagrams are computably enumerable.
We call these structures positive structures. The second class
is the class of structures for which the negative atomic diagrams
are computably enumerable. We call these structures negative
structures. We investigate definability of positive and negative
structures by sets of sentences quantified with Existential,
Universal, Existential-Universal and Universal-Existential
quantifiers using expansions of languages.
Core Model Seminar starting again in two weeks
Carnegie Mellon Logic Seminar
1/10/2023 13:02:19
TUESDAY, January 24, 2023
Core Model Seminar: 1:30-3 PM Eastern, Online, Takehiko Gappo, TU Wien
Join Zoom Meeting:
https://cmu.zoom.us/j/97749733438?pwd=Yk5PcSsvekptWWxMNUhCU2pFbzA0Zz09
Meeting ID: 977 4973 3438
Passcode: 457791
TITLE: Chang models over derived models
ABSTRACT: We will give a proof outline of the main theorem in Sargsyan's
paper, "Covering with Chang models over derived models." In this paper, he
constructed a new model of determinacy extending the derived model, called
the Chang model over the derived model, inside of a symmetric extension of
a least branch hod mouse with Woodin cardinals. This result will be used
in the next talk.
TUESDAY, January 31, 2023
Core Model Seminar: 1:30-3 PM Eastern, Online, Takehiko Gappo, TU Wien
Join Zoom Meeting:
https://cmu.zoom.us/j/97749733438?pwd=Yk5PcSsvekptWWxMNUhCU2pFbzA0Zz09
Meeting ID: 977 4973 3438
Passcode: 457791
TITLE: Determinacy in the Chang model from a hod pair
ABSTRACT: We will show that the Chang model satisfies determinacy from the
existence of an excellent least branch hod pair with a Woodin limit of
Woodin cardinals. The proof is based on Sargsyan's result on Chang models
over derived models. This is joint work with Sargsyan.
TUESDAY, February 7, 2023
Core Model Seminar: 1:30-3 PM Eastern, Online, Gabriel Goldberg,
University of California, Berkeley
Join Zoom Meeting:
https://cmu.zoom.us/j/97749733438?pwd=Yk5PcSsvekptWWxMNUhCU2pFbzA0Zz09
Meeting ID: 977 4973 3438
Passcode: 457791
TITLE: TBA; ABSTRACT: TBA
TUESDAY, February 14, 2023
Core Model Seminar: 1:30-3 PM Eastern, Online, Gabriel Goldberg,
University of California, Berkeley
Join Zoom Meeting:
https://cmu.zoom.us/j/97749733438?pwd=Yk5PcSsvekptWWxMNUhCU2pFbzA0Zz09
Meeting ID: 977 4973 3438
Passcode: 457791
TITLE: TBA; ABSTRACT: TBA
Cross-Alps Logic Seminar for World Logic Day (speaker: Vasco Brattka)
Cross-Alps Logic Seminar
1/9/2023 2:00:00
On Friday 13.01.2023 at 16:00
on the occasion of World Logic Day 2023, a special session of the Cross-Alps Logic Seminars will take place, with special guest
Vasco Brattka (Universität der Bundeswehr München)
who will give a talk on
Some fascinating topics in logic around reducibilities
Please refer to the usual webpage of our LogicGroup for more details and the abstract of the talk.
The seminar will be held remotely through Webex. Please write to vincenzo.dimonte [at] uniud [dot] it for the link to the event.
The Cross-Alps Logic Seminar is co-organized by the logic groups of Genoa, Lausanne, Turin and Udine as part of our collaboration in the project PRIN 2017 'Mathematical logic: models, sets, computability'.
Wednesday seminar
Prague Set Theory Seminar
1/8/2023 13:26:38
Dear all,
The seminar meets on Wednesday January 11th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Jaroslav Supina -- Katětov order on ideals and the
Fréchet-Urysohn property
We show that the Katětov order on ideals on natural numbers is a useful
tool in answering a question posed by J. Gerlits and Zs. Nagy and two
questions by M. Sakai. The questions are related to local topological
properties of a space of all continuous functions on an underlying
topological space, the most known among them being the Fréchet-Urysohn
property. This is a joint work with S. Bardyla and L. Zdomskyy.
Best,
David
(KGRC) seminar talks Tuesday, January 10 and Thursday, January 12
Kurt Godel Research Center
1/5/2023 15:45:05
The KGRC welcomes as guests:
Martin Hils (host: Matthias Aschenbrenner) visits the KGRC until March 31,
2023 and gives a talk on January 19, 2023 (details to be announced at a
later time).
Franz-Viktor Kuhlmann (host: Matthias Aschenbrenner) visits the KGRC until
January 31, 2023.
Clifton Ealy (host: Matthias Aschenbrenner) visits the KGRC until August
15.
Tomasz Żuchowski (host: Damian Sobota) visits the KGRC from January 9 to
January 17.
Jerzy Kąkol (host: Damian Sobota) visits the KGRC from February 27 to
March 3.
Manuel López Pellicer (host: Damian Sobota) visits the KGRC from February
27 to March 3.
* * *
Set Theory Research Seminar
Kurt Gödel Research Center
Tuesday, January 10
"A weak form of Global Choice under the GCH, part 1"
Peter Holy (TU Wien)
In 2012, Joel Hamkins asked (on MathOverflow) whether it is possible for
the universe of sets to have a linear ordering, but no wellordering (that
is, global choice fails). This question, which I consider very
interesting, appears to still be open. In my talk, I want to present a
somewhat related result. After providing a gentle introduction to second
order set theory and the principle of global choice (no knowledge on these
matters is assumed), we consider a different weakening of global choice
under the GCH: The minimal ordinal-connection axiom MOC due to Rodrigo
Freire. It is equivalent to the statement that the universe of sets can be
stratified by a subset-increasing hierarchy with
each K_alpha of the same size as alpha, and such that K_kappa=H(kappa),
the collection of sets of hereditary size less than kappa, for every
regular infinite cardinal kappa. In this form, it clearly implies the GCH,
and is easily seen to be a weak form of global choice under the GCH. We
will show, using class forcing products of adding Cohen subsets of regular
cardinals (without assuming any particular knowledge regarding the
technique of class forcing), that MOC can consistently fail in models of
the GCH, and that MOC can consistently hold while global choice fails.
This is joint work with Rodrigo Freire (University of Brasilia).
Time and Place
Talk at 3:00pm in hybrid mode, in person as well as via Zoom. (Students at Uni
Wien are required to attend in person.)
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
For details about how to join the Zoom session, please see the end of this
message.
* * *
Logic Colloquium
Kurt Gödel Research Center
Thursday, January 12
"Order-preserving Martin's Conjecture"
Benjamin Siskind (Carnegie Mellon University, US)
We'll talk about the current status of Martin's Conjecture, a conjecture
positing that, up to equivalence almost-everywhere, the only natural
functions on the Turing Degrees are the well-known ones: constant
functions, the identity, and transfinite iterates of the Turing Jump.
While the full conjecture is open even for low-level Borel functions, the
order-preserving case seems much more tractable. We'll discuss recent
progress on this order-preserving version of Martin's Conjecture.
This is joint work with Patrick Lutz.
Time and Place
Talk at 3:00pm in hybrid mode, in person as well as via Zoom. (Students at
Uni Wien are required to attend in person.)
Universität Wien
Institut für Mathematik
Kolingasse 14-16
1090 Wien
1st floor
Seminar room 10
Zoom for both talks: If you need the Zoom data and have not received the
meeting link by the day before the talk, please contact
richard.springer@univie.ac.at! (Please direct any other requests about the
Zoom meeting(s) to vera.fischer@univie.ac.at.)
Wednesday seminar
Prague Set Theory Seminar
1/2/2023 8:44:03
Dear all,
The seminar meets on Wednesday January 4th at 11:00 in the Institute of
Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.
Program: Jonathan Cancino Manriquez -- Ideal independent families and
ultrafilters
A family X of infinite subsets of natural numbers is an ideal
independent family if no element of X is almost contained in the union
of finitely many other sets in the family X. The ideal independence
number, s_mm, is defined as the minimal cardinality of an ideal
independent family. These notions were introduced by D. Monk several
years ago, and in joint work with O. Guzmán and A. Miller it was proved
that the dominating number is a lower bound for s_mm, among other
things. In recent work with V. Fischer and C. B. Switzer it was proved
that the ultrafilter number is a lower bound for s_mm, that the spectrum
of ideal independent families can be quite wide and also a preservation
theorem for ideal independent families along countable support
iterations. In this talk we will review some of these results.
Best,
David