• 2018 Nov 15

# Basic Notions seminar : Zlil Sela - Basic conjectures and preliminary results in non-commutative algebraic geometry

4:00pm to 5:15pm

## Location:

Ross 70
Speaker: Zlil Sela
Title: Basic conjectures and preliminary results in non-commutative algebraic geometry

Abstract: Algebraic geometry studies the structure of varieties over
fields and commutative rings. Starting in the 1960's ring theorists
(Cohn, Bergman and others) have tried to study the structure of varieties
over some non-commutative rings (notably free associative algebras).

The lack of unique factorization that they tackled and studied in detail,
and the pathologies that they were aware of, prevented any attempt
• 2018 Nov 15

# Colloquium: Ari Shnidman (Boston College) - Rational points on elliptic curves in twist families

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem
The rational solutions on an elliptic curve form a finitely generated abelian group, but the maximum number of generators needed is not known. Goldfeld conjectured that if one also fixes the j-invariant (i.e. the complex structure), then 50% of such curves should require 1 generator and 50% should have only the trivial solution. Smith has recently made substantial progress towards this conjecture in the special case of elliptic curves in Legendre form. I'll discuss recent work with Lemke Oliver, which bounds the average number of generators for general j-invariants.
• 2018 Nov 14

# Set Theory Seminar: Shimon Garti "On the consistency of d_lambda > r_lambda for a singular cardinal lambda"

2:00pm to 3:30pm

## Location:

Ross 63
Abstract: We shall try to prove the consistency of d_lambda > r_lambda (and even d_lambda > u_lambda) for a singular cardinal lambda. This is a joint work with Saharon.
• 2018 Nov 14

# Logic Seminar - Yair Hayut

11:00am to 1:00pm

## Location:

Ross 63

Global Chang's Conjecture

Yair Hayut - (joint with Monroe Eskew)

For $\kappa < \lambda$ infinite cardinals let us consider the following generalization of the Lowenheim-Skolem theorem:
"For every algebra with countably many operations over $\lambda^+$ there is a sub-algebra with order type exactly $\kappa^+$".

We will discuss the consistency and inconsistency of some global versions of this statement and present some open questions.
• 2018 Nov 13

# Dynamics Seminar: Amir Algom (HUJI) Slicing Theorems for products of Cantor sets and self affine carpets

2:15pm to 3:15pm

Ross 70
• 2018 Nov 13

# Dynamics Lunch: Jakub Konieczny "Sarnak conjecture and automatic sequences (following C. Müllner and M. Lemańczyk)"

12:00pm to 1:00pm

## Location:

Manchester faculty club
• 2018 Nov 12

# NT&AG: Zev Rosengarten

2:30pm to 3:30pm

## Location:

Ross 70

Title: Tamagawa Numbers of Linear Algebraic Groups over Function Fields

• 2018 Nov 12

# NT & AG Lunch: Yakov Varshavsky "Langlands conjectures"

1:00pm to 2:00pm

## Location:

Faculty lounge, Math building
The goal of my talk will be to formulate local and global Langlands conjectures Key words: smooth representations of p-adic groups, supercuspidal representations, automorphic representations, cusp forms, Galois representations.
• 2018 Nov 12

# Combinatorics: Michael Chapman, HU, TBA

11:00am to 1:00pm

## Location:

Rothberg CS bldg, room B500, Safra campus, Givat Ram
Speaker: Michael Chapman, HU Title: Graphs which are expanders both locally and globally Abstract:
• 2018 Nov 11

# Kazhdan seminar: Karim Adiprasito "Positivity in combinatorics and beyond"

3:00pm to 5:00pm

## Location:

Ross 70A
Abstract: I will discuss applications of algebraic results to combinatorics, focusing in particular on Lefschetz theorem, Decomposition theorem and Hodge Riemann relations. Secondly, I will discuss proving these results combinatorially, using a technique by McMullen and extended by de Cataldo and Migliorini. Finally, I will discuss Lefschetz type theorems beyond positivity. Recommended prerequisites: basic commutative algebra