Dear all,

The seminar meets on Wednesday June 27th at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Jindra Zapletal will present a talk.

Best,

David

Global set theory seminar and conference announcements

Dear all,

The seminar meets on Wednesday June 27th at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Jindra Zapletal will present a talk.

Best,

David

Dear all,

The seminar meets on Wednesday June 20th at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Program: Mirna Džamonja — Higher order versions of the logic of chains

close

First order logic of chains was discovered by Carol Karp and revisited

in recent work of Dz. with Jouko Vaananen. The results have shown that

the logic, defined through a singular cardinal of countable cofinality,

behaves very much like the first order logic. In our new joint work, we

study higher order versions of the logic of chains and their fragments

to defend the thesis that in this context we can also recover

similarities with the ordinary logic. We also discuss the idea of

infinite computation.

Best,

David

The seminar meets on Wednesday June 6t at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Speaker: Viera Šottová

Title: Ideal version of selection principle $S_1(\mathcal P,\mathcal R)$.

Abstract: attached.

Dear all,

The seminar meets on Wednesday May 23rd at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Program: Damian Sobota — Rosenthal families and ultrafilters

Rosenthal’s lemma is a simple technical result with numerous

applications to measure theory and Banach space theory. The lemma in its

simplest form reads as follows: “For every infinite real-entried matrix

(m(n,k): n,k in N) such that every entry is non-negative and the sum of

every row is <=1, and every epsilon>0, there exists an infinite subset A

of N such that for every k in A we have sum_{n in A, n\neq

k}m_n^k<epsilon.” A natural question arises whether we can choose the

set A from a previously fixed family F of infinite subsets of N. If F

has such a property, then we call it Rosenthal. Thus, Rosenthal’s lemma

states that [N]^omega is Rosenthal. During my talk I’ll present some

necessary or sufficient conditions for a family to be Rosenthal and

prove that under MA(sigma-centered) there exists a P-point which is a

Rosenthal family but not a Q-point. (No Banach space will appear during

the talk.)

Best,

David

Dear all,

The seminar meets on Wednesday May 9th at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Program: Jonathan Verner — Ultrafilters and nonstandard models of

arithmetic

(This is a talk postponed from April 18th.)

Best,

David

The seminar meets on Wednesday April 18th at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Program: Jonathan Verner — Ultrafilters and models of arithmetic

Dear all,

The seminar meets on Wednesday April 11th at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Program: Wojciech Wołoszyn will be presenting results about Laver type

posets from the paper of J. Zapletal and myself.

Best,

David

Dear all,

The seminar meets on Wednesday April 4th at 11:00 in the Institute of

Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

We will have a guest speaker Andrew Brooke-Taylor.

Best,

David

Dear all,

The seminar meets on Wednesday March 28th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building.

Program: Borisa Kuzeljevic — Isomorphic substructures of Fraisse limits

This is joint work with Milos Kurilic. For a relational structure X, its poset of copies is the set of all the substructures of X which are isomorphic to X, enlarged with the empty set, and ordered by inclusion. We will analyze posets of copies of various countable ultrahomogeneous structures. In particular, we will show that for many of these structures the class of order types of maximal chains of copies coincides with the class of order types of compact sets of reals with minimum non-isolated.

Best,

David