2018
Nov
26

# Seminars

2018
Nov
27

# T&G: Graham Denham (Western University), Cohomological vanishing and abelian duality

2:00pm to 3:30pm

## Location:

Room 209, Manchester Building, Jerusalem

Cohomology jump loci are secondary cohomological invariants of discrete groups and topological spaces. I will describe some recent work on the cohomology jump loci of complements of unions of smooth complex hypersurfaces, and I will motivate the notion of abelian duality spaces that I introduced in joint work with Alex Suciu and Sergey Yuzvinsky. The study of such hypersurface arrangements involves a mix of combinatorics and complex geometry.

2018
Nov
27

# Yan Dolinsky. A new type of stochastic target problems.

12:00pm to 1:00pm

## Location:

Coffee lounge

Abstract: I will discuss two stochastic target problem in the Brownian framework .
The first problem has a nice solution which I will present. The second problem
is much more complicated and for now remains open. I will discuss the challenges and connection with other fields in probability theory.

2019
Jan
08

# Godofredo Iommi (PUC), Upper semi-continuity of the entropy map for Markov shifts

2:15pm to 3:15pm

Abstract: In this talk I will show that for finite entropy countable Markov shifts the entropy map is upper semi-continuous when restricted to the set of ergodic measures. This is joint work with Mike Todd and Anibal Velozo.

2018
Dec
05

# Set Theory Seminar: Ur Yaar

2:00pm to 3:30pm

2018
Dec
12

# Set Theory Seminar: Yair Hayut "Chang's Conjecture" (Part III)

2:00pm to 3:30pm

## Location:

Ross 63

Title: Chang's Conjecture (joint with Monroe Eskew)
Abstract:
I will review some consistency results related to Chang's Conjecture (CC).
First I will discuss some classical results of deriving instances of CC from huge cardinals and the new results for getting instances of CC from supercompact cardinals, and present some open problems.
Then, I will review the consistency proof of some versions of the Global Chang's Conjecture - which is the consistency of the occurrence many instances of CC simultaneously.
We will aim to show the consistency of the statement: (\mu^+,\mu) -->> (
u^+,

2018
Nov
28

# Set Theory Seminar: Yair Hayut "Chang's Conjecture" (Part II)

2:00pm to 3:30pm

## Location:

ross 63

Title: Chang's Conjecture (joint with Monroe Eskew)
Abstract:
I will review some consistency results related to Chang's Conjecture (CC).
First I will discuss some classical results of deriving instances of CC from huge cardinals and the new results for getting instances of CC from supercompact cardinals, and present some open problems.
Then, I will review the consistency proof of some versions of the Global Chang's Conjecture - which is the consistency of the occurrence many instances of CC simultaneously.
We will aim to show the consistency of the statement: (\mu^+,\mu) -->> (
u^+,

2018
Nov
26

# Combinatorics: Ron Adin, BIU, "Cyclic permutations, shuffles and quasi-symmetric functions"

11:00am to 1:00pm

## Location:

Rothberg CS bldg, room B500, Safra campus, Gival Ram

Speaker: Ron Adin, Bar-Ilan University
Title: Cyclic permutations, shuffles and quasi-symmetric functions
Abstract:
By a theorem of Stanley, the distribution of descent number over all the shuffles of two permutations depends only on the descent numbers of these permutations. For a quantitative version of this result and its cyclic analogue, we use a new cyclic counterpart of Gessel's ring of quasi-symmetric functions, together with an unusual homomorphism and a mysterious binomial identity.
No previous acquaintance assumed.

2018
Nov
27

2019
Jan
02

# Analysis Seminar: Martin Fraas (Virginia) "A many-body index for quantum charge transport"

12:00pm to 1:00pm

## Location:

Ross building, room 70

Title: A many-body index for quantum charge transport

2018
Nov
21

# Logic Seminar - Saharon Shelah

11:00am to 1:00pm

## Location:

Ross 63

**קשת איוּם מוֹדל כוֹלל**

**the spectrum of the existence of a universal model**

**תמצית/abstract:**

קיוּם מוֹדל כולל של תורה בעצמה נתוּנה זו שאלה טבעית בתוֹרת המוֹדלים ובתוֹרת הקבוּצוֹת. נטפל בתנאים מספיקים לאי קיוּם, אין צוֹרך בידיעוֹת מוּקדמוֹת.

The existence of a universal model (of a theory T in a cardinal lambda) is a natural question in model theory and set theory. We shall deal with new sufficient conditions for non-existence.

No need of previous knowledge

2018
Nov
28

# Logic Seminar - Spencer Unger

11:00am to 1:00pm

## Location:

Ross 63

**A constructive solution to Tarski's circle squaring problem**

**Spencer Unger**

2018
Dec
26

# Logic Seminar - Antongiulio Fornasiero

11:00am to 1:00pm

## Location:

Ross 63

**Generic derivations on o-minimal structures**

**Antongiulio Fornasiero**

A derivation on a field K is a map d from K to K such that d(x + y) = d(x) + d(y) and d(x y) = x d(y) + d(x) y.

Given an o-minimal structure M in a language L, we introduce the notion L-derivation, i.e derivation compatible with L. For example, if M is the field of reals with exponentiation, then we further require that the derivation d satisfies d(exp x) = exp(x) d(x).

2018
Dec
03

# Combinatorics: Kai Fong Ernest Chong, SUTD Singapore, "Stress algebras on simplicial complexes"

11:00am to 1:00pm

## Location:

Rothberg CS bldg, room B500, Safra campus, Givat Ram

Speaker: Kai Fong Ernest Chong, SUTD, Singapore
Title: Stress algebras on simplicial complexes
Abstract:

2018
Nov
20

# T&G: Gangotryi Sorcar (Hebrew University), On the topology of the Teichmuller space of negatively curved Riemannian metrics

2:00pm to 3:30pm

## Location:

Room 209, Manchester Building, Jerusalem

This talk is a survey on results concerning the Teichmuller space of negatively curved Riemannian metrics on M. It is defined as the quotient space of the space of all negatively curved Riemannian metrics on M modulo the space of all isotopies of M that are homotopic to the identity. This space was shown to have highly non-trivial homotopy when M is real hyperbolic by Tom Farrell and Pedro Ontaneda in 2009.