2018
Apr
11

# Seminars

2018
Apr
15

2018
May
22

2018
May
22

2017
Mar
08

# Logic seminar - Yair Hayur, "Radin Forcing and model without weak diamond"

4:00pm to 6:00pm

## Location:

Ross 70

Abstract: We continue with the topic of the previous week. We will define the Radin forcing, discuss (without proof) and its basic properties. We will give Woodin's proof for the consistency of the existence of strong inaccessible without diamond and show how to strengthen it to the consistency of strong inaccessible without weak diamond.

2017
Jul
10

# Special logic seminar - Noa Lavi, "Independent chapters in dependent theories"

11:00am to 1:00pm

## Location:

Ross 70

This talk is about three published papers of mine that form my phd. In the first two chapters I focus in the model theory of real closed fields and in the third one I take one step back and investigate in greater genearility dependent theories.
The results are the following:
1. Boundedness criterion for rational functions over generalized semi-algebraic sets in real closed fields.
2. Positivity criterion for polynomials over generalized semi-algebraic sets in real closed valued fields.

2018
May
02

# Logic Seminar - Chloe Perin - "Forking in the free group"

12:00pm to 2:00pm

## Location:

Ross 63

Sela proved that the theory of free groups is stable. It is thus natural to wonder what the independence relation looks like. Together with Sklinos, we worked out a complete characterization of forking independence in the standard model (over any set of parameters) in terms of an algebraic-geometric object called the JSJ decomposition, which encodes all the splittings of the group as an amalgamated product or an HNN extension relative to the parameter set.
In the talk we will try to give an idea of the proof over some examples.

2017
Dec
06

# Logic Seminar - Daoud Siniora - "Automorphism groups of homogeneous structures"

11:00am to 1:00pm

## Location:

Math 209

A special class among the countably infinite relational structures is the class of homogeneous structures. These are the structures where every finite partial isomorphism extends to a total automorphism. A countable set, the ordered rationals, and the random graph are all homogeneous.

2018
May
01

# Logic Seminar - Asaf Karagila - "What can you say about critical cardinals?"

1:30pm to 3:30pm

We isolate the property of being a critical point, and prove some basic positive
properties of them. We will also prove a lifting property that allows lifting
elementary embedding to symmetric extensions, and outline a construction that
shows that it is consistent that a successor of a critical cardinal is singular.
This is a recent work with Yair Hayut.

2017
Mar
22

# Logic seminar - Chris Lambie-Hanson, "Trees with ascent paths"

4:00pm to 6:00pm

## Location:

Ross 70

Abstract: The notion of an ascent path through a tree, isolated by Laver, is a generalization of the notion of a cofinal branch and, in many cases, the existence of an ascent path through a tree provides a concrete obstruction to the tree being special. We will discuss some recent results regarding ascent paths through kappa-trees, where kappa > omega_1 is a regular cardinal. We will discuss the consistency of the existence or non-existence of a special mu^+-tree with a cf(mu)-ascent path, where mu is a singular cardinal.

2017
Apr
24

# Logic seminar

Repeats every week every Monday until Sun May 21 2017 except Mon May 01 2017.

12:00pm to 2:00pm12:00pm to 2:00pm

12:00pm to 2:00pm

## Location:

Ross 63

We will take a close look at the first few steps of the construction of the Bristol model, which is a model intermediate to L[c], for a Cohen real c, satisfying V
eq L(x) for all x.

2018
Jun
27

# Logic Seminar - Shahar Oriel - TBA

11:00am to 1:00pm

2017
Nov
22

# Logic Seminar - Yair Hayut - "Chang's Conjecture at many cardinals simultaneously"

11:00am to 1:00pm

## Location:

Math 209

Chang's Conjecture is a strengthening of Lowenheim-Skolem-Tarski theorem. While Lowenheim-Skolem-Tarski theorem is provable in ZFC, any instance of Chang's Conjecture is independent with ZFC and has nontrivial consistency strength. Thus, the question of how many instances of Chang's Conjecture can consistently hold simultaneously is natural.

I will talk about some classical results on the impossibility of some instances of Chang's Conjecture and present some results from a joint work with Monroe Eskew.

2018
Jun
13

2017
Jun
28

# Logic seminar - Shimon Garti, "Tiltan"

4:00pm to 6:00pm

## Location:

Ross 70

We shall try to prove some surprising (and hopefully, correct) theorems about the relationship between the club principle (Hebrew: tiltan) and the splitting number, with respect to the classical s at omega and the generalized s at supercompact cardinals.