## Dana Bartosova: About the conjecture that oligomorphic groups have metrizable universal minimal flows

Place:  Fields Institute (Room 210)

Date: 27-March-2015 (13:30-15:00)

Title: About the conjecture that oligomorphic groups have metrizable
universal minimal flows
Abstract: We will discuss a conjecture of Lionel Nguyen van Th\’e as
in the title. It was shown by Andy Zucker to be equivalent to whether
every class of finitary approximations of a countable ultrahomogeneous structure with oligomorphic automorphism group has a finite Ramsey degree. We look at the problem from the Boolean algebra point of view. An interesting example in this context is the automorphism group of a topological structure whose natural quotient is the pseudo-arc, which is a work in progress with Aleksandra Kwiatkowksa (UCLA).

## Oleg Gutik: Around the bicyclic monoid: topological and semigroup views

Wednesday, April 1, 2015, 17:15
Wrocław University of Technology, 215 D-1

Speaker: Oleg Gutik (National University of Lviv)

Title: Around the bicyclic monoid: topological and semigroup views

Abstract:

We discuss algebraic and topological properties of (semitopological and topological) semigroups which are close to the bicyclic monoid: the semigroup of matrix units, the semigroup of co-finite partial bijections and the polycyclic monoid. We speak about topologizations of such semigroups as topological or semitopological semigroups, their embeddings into compact-like topological semigroups and their closures in topological semigroups.

## 8th Young Set Theory Workshop, October 25-30, 2015

The 8th Young Set Theory Workshop will take place October 25-30 2015, at the Israel Institute of Advanced Studies in Jerusalem.

The aims of the “Young Set Theory Workshops” are to bring together young researchers in the domain of set theory and give them the opportunity to learn from each other and from experts in a friendly environment. A long-term objective of this series of workshops is to create and maintain a network of young set theorists and senior researchers, so as to establish working contacts and help disseminate knowledge in the field.

To register and apply for financial support, use this link.

There will be four minicourses, five invited talks by young set theorists, and a few more invited 1-hour talks by senior set theorists.

### MINICOURSES:

 Alexander S. Kechris (Caltech) [tentative] Péter Komjáth (Eötvös) Menachem Magidor (HUJI) W. Hugh Woodin (Harvard)

## Graduate Summer School in Set Theory (Irvine), July 6 – 17, 2015

There will be a summer school for graduate students in set theory from July 6 through July 17, 2015, at the University of California, Irvine. The summer school is supported by NSF Grant DMS-1044150.

The webpage for the program is here: https://gssst2015.wordpress.com/

The goal of the course is to learn about advanced topics in forcing and large cardinals. The final program will depend on the experience level of the participants, but would likely include: forcing axioms and applications; infinite combinatorics (tree property, square, etc.); behavior of the continuum function; and theory of ideals and generic elementary embeddings. Please see the website for more information about prerequisites.

The course instructors are Brent Cody (VCU), Monroe Eskew (VCU), and Spencer Unger (UCLA). The organizer is Sean Cox (VCU).

The school is able to provide full support to US citizens and permanent residents. Foreign students are welcomed to participate, but would need to obtain funding from their universities or advisers.

Please email the organizer, Sean Cox (scox9@vcu.edu), with any questions.

## Frank Stephan: Automatic Structures – recent results and open questions

Invitation to the Logic Seminar at the National University of Singapore

Date: Wednesday, 25 March 2015, 17:00 hrs

Room: S17#05-11, Department of Mathematics, NUS

Speaker: Frank Stephan

Title: Automatic Structures – recent results and open questions

URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Abstract:
Automatic structures are a way to represent algebraic
structures using finite automata; all the algebraic operations
and relations have to be recognised / verified by finite automata
which read the inputs and outputs with the same speed (one symbol
per cycle). The talk gives an overview on what structures can
be represented this way and which questions are left open in
the field.

## Robert Rałowski: Two point sets, continuation

Tuesday, March 24, 2015, 17:15
Wrocław University of Technology, 215 D-1

Speaker: Robert Rałowski (Wrocław University of Technology)

Title: Two point sets, continuation

Abstract:

We will continue discussion started a week ago concerning two point sets. We will give another example of a property of two point set which is consistent with ZFC.

## Mike Pawliuk: Amenability and Directed Graphs Part 2 (Cherlin’s List)

Place:  Fields Institute (Room 230)

Date: 20-March-2015 (13:30-15:00)

Title: “Amenability and Directed Graphs Part 2 : Cherlin’s List”
Abstract: Last week Miodrag spoke in general about Amenability, Fraisse classes and consistent random expansions. This talk will be more specific and focus on checking the amenability and unique ergodicity of the automorphism groups of the directed graphs on Cherlin’s list. In addition, we will present a type of product of Fraisse classes that behaves nicely with respect to amenability and unique ergodicity.

## Chris Lambie-Hanson: Coloring classes and the Hanf number for amalgamation.

Set Theory and Topology seminar (BGU)
Notice the one-time change in place to +201.

Time: Tuesday, March 24, 12:15-13:40.
Place: Seminar room +201, Math building 58.
Speaker: Chris Lambie-Hanson (HUJI).
Title: Coloring classes and the Hanf number for amalgamation.
Abstract: The amalgamation property is a topic of fundamental importance in model theory and is still imperfectly understood. In the 1980s, Grossberg asked a question, which remains open, about the existence of a Hanf number for amalgamation in abstract elementary classes. In particular, Grossberg conjectured that the Hanf number for amalgamation for classes given by an $L_{\omega_1, \omega}$ sentence is $beth_{omega_1}$. We introduce a new collection of abstract elementary classes, called coloring classes, and use them to give a partial answer to Grossberg’s question, significantly improving upon work of Baldwin, Kolesnikov, and Shelah. Analysis of these coloring classes leads to some purely combinatorial questions that are of interest in their own right. This is joint work with Alexei Kolesnikov.

## Xianghui Shi: Large cardinals and generalized degree structures

Mathematical logic seminar – March 24, 2015
Time:     12:30 – 13:30

Room:     Wean Hall 8201

Speaker:         Xianghui Shi
School of Mathematical Sciences
Beijing Normal University

Title:     Large cardinals and generalized degree structures

Abstract:

The notion of Turing degree can be generalized to large ordinals, in particular to uncountable cardinals. Sy Friedman showed that in Jensen’s constructible universe, the generalized degree structure at singular cardinals of uncountable cofinality is eventually well ordered. I will present an interesting new degree structure at singular cardinals of countable cofinality in the core model for a certain large cardinal. In this talk, I will also discuss the correlation between the complexity of degree structures and the strength of relevant large cardinals.

## 2-years Postdoc Position in Mathematical Logic in Torino (train2move)

There is an opportunity to apply for a 2-years fellowship in Torino University Mathematics Department in the field of Mathematical Logic with a focus in Descriptive Set Theory (to be meant with the broadest possible meaning). The details on the application can be found at: http://www.train2move.unito.it/data/T2M_Callforproposals_2015.pdf, and the website on which one can gather all infomations is: http://www.train2move.unito.it/login.html.

The deadline is 5th of may 2015. Those interested to apply can contact one of the following members of the logic group of the mathematics department in Torino:

Best regards, Matteo Viale