## Andres Caicedo: Ramsely theory of very small countable ordinals II

Wednesday, October 1 from 3 to 4pm
Room: Math 226
Speaker: Andrés Caicedo (BSU)
Title: Ramsey theory of very small countable ordinals II

Abstract: We examine a closed version of the pigeonhole principle for ordinals, and use it to draw upper bounds on closed Ramsey numbers.

## Will Boney: Some Model Theory of Torsion Modules

Model Theory Seminar

Will Boney

University of Illinois at Chicago

Title:   Some Model Theory of Torsion Modules

Abstract:   We explore some model theory of torsion modules, first over commutative rings and then specializing to PIDs.  Despite being a nonelementary class, there is a high degree of “compactness” in the guise of tameness and type shortness.  We conclude by looking at some examples of various torsion abelian groups and applying various independence relations proposed for AECs.

Date: Monday, October 6, 2014

Time: 5:00 – 6:30 PM
Location: Wean 8220

## Keng Meng Ng: Constructing minimal pairs.

Invitation to the Logic Seminar at the National University of Singapore

Date: Wednesday, 01 October 2014, 17:00 hrs

Room: S17#04-04, Department of Mathematics, NUS

Speaker: Keng Meng Ng

Title: Constructing minimal pairs.

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

Abstract: We show how to use the determinacy of finite games to construct
minimal pairs in the truth-table degrees.

## Andrés Caicedo: Ramsey theory of very small countable ordinals

Wednesday, September 24 from 3 to 4pm
Room: Math 226
Speaker: Andrés Caicedo (BSU)
Title: Ramsey theory of very small countable ordinals

Abstract: We present a brief introduction to classical Ramsey theory, and discuss two extensions in the context of ordinals. We limit ourselves to small countable ordinals, emphasizing those smaller than $\omega^2$.

## Daniel Soukup: Trees, ladders and graphs

Friday 19 September Fields Institute, Room 210, 13:30-15:00

Speaker: Daniel Soukup
Title:  Trees, ladders and graphs

## Clinton Conley : An introduction to Borel graph theory II

Mathematical logic seminar – September 23, 2014

Time:     12:30 – 13:30

Room:     Wean Hall 8220

Speaker:         Clinton Conley
Department of Mathematical Sciences
Carnegie Mellon University

Title:     An introduction to Borel graph theory II

Abstract:

We discuss the theory of Borel graphs on standard Borel spaces, which has been a fertile topic of research in recent decades. While results in this purely Borel context are interesting on their own, we pay special attention to the “measure-theoretic” context in which the underlying space is equipped with a standard probability measure and null sets are discarded at one’s fancy. Results in this setting have connections with a variety of areas of mathematics including graph limits, ergodic theory, and probability. Our particular goals for this talk, after defining various notions, are to show ease of coloring graphs with μ-a.e. hyperfinite connectedness relation and to construct examples of graphs which are hard to color.

## Mid-Atlantic Mathematical Logic Seminar, October 25-26, 2014

The Fall 2014 Rutgers Logic Meeting will take place at Rutgers University on October 25-26, 2014. The invited speakers are Ilijas Farah, Andrew Marks, Justin Moore, Saharon Shelah, Dima Sinapova, and Nam Trang. The lectures will take place in Room 221 in Scott Hall on College Avenue Campus.

Schedule

Saturday October 25, Room 221 in Scott Hall

• 9:00-9:30 Coffee

• 9:30–10:30
Saharon Shelah (Rutgers)
Title:

• 11–12
Nam Trang (CMU)

• 12–2
Lunch

• 2–3
Andrew Marks (UCLA)

• 3–3:30 Coffee

• 3:30– 4:30
Justin Moore (Cornell)

Sunday October 26, Room 221 in Scott Hall

• 9:30–10 Coffee

• 10–11
Dima Sinapova (UIC)

• 11:30–12:30
Ilijas Farah (York)

## Yang Yue: On a Question of Cholak and Downey

Invitation to the Logic Seminar at the National University of Singapore

Date: Wednesday, 17 September 2014, 17:00 hrs

Room: S17#04-04, Department of Mathematics, NUS

Speaker: Yang Yue

Title: On a Question of Cholak and Downey

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

In a paper entitled “On the Cantor-Bendixon rank of recursively
enumerable sets” (JSL 1993), Cholak and Downey showed that for every
recursive ordinal alpha and every nonrecursive r.e. degree d,
there is an r.e. set of rank alpha and degree d.
They also asked if one can generalize the result to
Delta-0-2 degrees, i.e., for every recursive
ordinal alpha and every nonrecursive Delta-0-2
degree d there is a Delta-0-2 set of rank
alpha and degree d. I will show the answer is positive.

This is a joint work with Rod Downey and Guohua Wu.

## Clinton Conley: An introduction to Borel graph theory

Mathematical logic seminar – September 16, 2014
Time:     12:30 – 13:50Room:     Wean Hall 8220

Speaker:         Clinton Conley
Department of Mathematical Sciences
Carnegie Mellon University

Title:     An introduction to Borel graph theory

Abstract:

We discuss the theory of Borel graphs on standard Borel spaces, which has been a fertile topic of research in recent decades. While results in this purely Borel context are interesting on their own, we pay special attention to the “measure-theoretic” context in which the underlying space is equipped with a standard probability measure and null sets are discarded at one’s fancy. Results in this setting have connections with a variety of areas of mathematics including graph limits, ergodic theory, and probability. Our particular goals for this talk, after defining various notions, are to show ease of coloring graphs with $\mu$-a.e. hyperfinite connectedness relation and to construct examples of graphs which are hard to color.

## Model Theory Seminars on Monday 5-6:30PM 9/15 & 9/22

Model Theory Seminar

Carnegie Mellon University

Title:   Superstable Fields and Groups – Part I

Abstract:  This series of talks will focus on proving a theorem of Cherlin and Shelah

(1980): If F is an infinite field with a superstable theory, then F is algebraically closed. This extends a result by Macintyre (1971) which states that any infinite omega-stable field is algebraically closed. The proof proceeds via results about stable groups, which are applied to the additive and multiplicative groups of a field F, along with the superstability assumption and elementary Galois theory.

The first talk will focus on an indecomposability theorem for stable groups (which we will later apply to our field).

Date: Monday, September 15, 2014
Time: 5:00 – 6:30 PM
Location: Wean 8220
—————————————————————————
Model Theory Seminar

Carnegie Mellon University

Title:   Superstable Fields and Groups – Part II

Abstract:  This series of talks will focus on proving a theorem of Cherlin and Shelah

(1980): If F is an infinite field with a superstable theory, then F is algebraically closed. This extends a result by Macintyre (1971) which states that any infinite omega-stable field is algebraically closed. The proof proceeds via results about stable groups, which are applied to the additive and multiplicative groups of a field F, along with the superstability assumption and elementary Galois theory.

The first talk will focus on an indecomposability theorem for stable groups (which we will later apply to our field).

Date: Monday, September 22, 2014

Time: 5:00 – 6:30 PM
Location: Wean 8220