2017
Dec
25

# Events & Seminars

2016
Nov
28

# NT&AG: Boris Zilber (University of Oxford), "On algebraically closed field of characteristic 1"

2:00pm to 3:00pm

## Location:

Ros Building, 70A

Abstract: I will start with a motivation of what algebraic (and model-theoretic) properties
an algebraically closed field of characteristic 1 is expected to have. Then I will explain
how these properties can be obtained by the well-known in model theory Hrushovski's
construction and then formulate very precise axioms that such a field must satisfy.
The axioms have a form of statements about existence of solutions to systems
of equations in terms of a 'multi-dimansional' valuation theory and the validity
of these statements is an open problem to be discussed.

2017
Apr
03

# NT&AG: Izzet Coskun (University of Illinois at Chicago), "Birational geometry of moduli spaces of sheaves on surfaces"

4:00pm to 5:00pm

## Location:

Tel Aviv University, Schreiber building, 209

Abstract: In the last five years Bridgeland stability has revolutionized
our understanding of the geometry of moduli spaces of sheaves on surfaces,
allowing us to compute ample and effective cones and describe different
birational models. In this talk, I will survey some of my joint work with
Daniele Arcara, Aaron Bertram, Jack Huizenga and Matthew Woolf on the
birational geometry of moduli spaces of sheaves on the plane. I will
describe the ample and effective cones of these moduli spaces,
concentrating on Hilbert schemes of points and concrete examples.

2015
Dec
22

# Number theory: Alexei Entin (Stanford) "Monodromy of Hurwitz spaces and extensions of F_q(t)"

10:30am to 11:45am

## Location:

Ross Building, room 70A

Hurwitz spaces are moduli spaces for extensions of curves with prescribed ramification types. They arise naturally when enumerating extensions of global function fields and also in many other contexts.
The classical Hurwitz space H_{m,n} may be viewed as a finite cover of the space of n-sets of points on P^1. We will show that this cover has a big monodromy group for n>4.
This can be applied to study the statistics of extensions of F_q(t) with varying branching locus in the large q limit. Joint work with Chris Hall and Robert Guralnick.

2017
Dec
25

# NG&AT: Avner Segal (UBC) "Poles of the Standard L-function and Functorial Lifts for G2"

3:00pm to 4:00pm

## Location:

Room 70A, Ross Building, Jerusalem, Israel

The functoriality conjecture is a key ingredient in the theory of automorphic forms and the Langlands program. Given two reductive groups G and H, the principle of functoriality asserts that a map r:H^->G^ between their dual complex groups should naturally give rise to a map r*:Rep(H)->Rep(G) between their automorphic representations. In this talk, I will describe the idea of functoriality, its connection to L-functions and recent work on weak functorial lifts to the exceptional group of type G_2.

2016
Mar
17

# Number theory

Repeats every week every Thursday until Thu Jun 16 2016 except Thu Apr 14 2016.

12:00pm to 1:15pm12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

12:00pm to 1:15pm

## Location:

Ross Building, room 63, Jerusalem, Israel

In his investigation of modular forms of half-integral weight, Shimura established, using Hecke theory, a family of relations between eigneforms of half-integral weight k+1/2 with a given level 4N and character chi and cusp forms of weight 2k and character chi^2.
The level being subsequently determined by Niwa to be at most 2N.

2017
Feb
27

# NT&AG: Stephen Lichtenbaum (Brown University), "A conjectured cohomological description of special values of zeta-functions"

2:00pm to 3:00pm

## Location:

Ross 70A

Abstract: Let X be a regular scheme, projective and flat over Spec Z. We
give a conjectural formula in terms of motivic cohomology, singular
cohomology and de Rham cohomology for the special value of the
zeta-function of X at any rational integer. We will explain how this
reduces to the standard formula for the residue of the Dedekind
zeta-function at s = 1.
האירוע הזה כולל שיחת וידאו ב-Google Hangouts.

2017
Nov
06

# NT&AG: Walter Gubler (University of Regensburg), "The non-archimedean Monge-Ampère problem"

2:00pm to 3:00pm

## Location:

Ros 70

Abstract: Calabi conjectured that the complex Monge-Ampère equation on compact Kaehler manifolds has a unique solution. This was solved by Yau in 1978. In this talk, we present a non-archimedean version on projective Berkovich spaces. In joint work with Burgos, Jell, Künnemann and Martin, we improve a result of Boucksom, Favre and Jonsson in the equicharacteristic 0 case. We give also a result in positive equicharacteristic using test ideals.

2016
Apr
21

# Number Theory: Benjamin Matschke (University of Bordeaux) "A database of rational elliptic curves with given bad reduction"

2:00pm to 3:15pm

## Location:

TBA

In this talk we present a database of rational elliptic curves with
good reduction outside certain finite sets of primes, including the
set {2, 3, 5, 7, 11}, and all sets whose product is at most 1000.
In fact this is a biproduct of a larger project, in which we construct
practical algorithms to solve S-unit, Mordell, cubic Thue, cubic
Thue--Mahler, as well as generalized Ramanujan--Nagell equations, and
to compute S-integral points on rational elliptic curves with given
Mordell--Weil basis.
Our algorithms rely on new height bounds, which we obtained using the

2016
Dec
19

# NT&AG: Edva Roditty-Gershon (University of Bristol), "Arithmetic statistics in function fields"

2:00pm to 3:00pm

## Location:

Manchester Building, Faculty Lounge

Abstract: In the talk I will discuss classical problems concerning the distribution
of square-full numbers and their analogues over function fields. The
results described are in the context of the ring Fq[T ] of polynomials
over a finite field Fq of q elements, in the limit q → ∞.
I will also present some recent generalization of these kind of
classical problems.
האירוע הזה כולל שיחת וידאו ב-Google Hangouts.

2017
Jun
05

# NT&AG: Simon Marshall (University of Wisconsin), "Endoscopy and cohomology growth on U(n,1) Shimura varieties"

2:00pm to 3:00pm

## Location:

Ros 70

Using the endoscopic classification
of automorphic forms for unitary groups,
I will prove conjecturally sharp upper
bounds for the growth of Betti numbers
in congruence towers of complex
hyperbolic manifolds. This is
joint work with Sug Woo Shin.
האירוע הזה כולל שיחת וידאו ב-Google Hangouts.
הצטרף: https://plus.google.com/hangouts/_/calendar/ODdkc2JxNmlmbjNhZ2U0ODVvb3E3...

2016
Mar
17

# Number theory

Repeats every week every Thursday until Wed Mar 16 2016 .

12:00pm to 1:15pm## Location:

Ross Building, room 70, Jerusalem, Israel

2018
Jan
08

# NT&AG: Hershy Kisilevsky (Concordia University), "Special Values of twists of Modular/Elliptic L-Functions"

2:00pm to 3:00pm

## Location:

Room 70A, Ross Building, Jerusalem, Israel

Let L(E/Q, s) be the L-function of an elliptic curve E defined over the rational field Q. We examine the central value L(E, 1, χ) of twists of L(E/Q, s) by Dirichlet characters χ. We discuss the vanishing and non-vanishing frequencies of these values as χ ranges over characters of fixed order greater than 2. We also examine thee square-free part of the algebraic part of L(E/F, 1) for abelian fields F/Q when these values are non-zero.

2016
Dec
12

# NT&AG: Amnon Yekutieli (BGU), "The Derived Category of Sheaves of Commutative DG Rings"

2:00pm to 3:00pm

## Location:

Ros Building, 70A

Abstract: In modern algebraic geometry we encounter the notion of derived intersection of subschemes. This is a sophisticated way to encode what happens when two subschemes Y_1 and Y_2 of a given scheme X intersect non-transversely. The classical intersection multiplicity can be extracted from the derived intersection.

2017
May
29

# NT&AG: Nicolas Templier (Cornell University), "Mirror symmetry for minuscule flag varieties"

2:00pm to 3:00pm

## Location:

Ros70A

We prove cases of Rietsch mirror conjecture that the quantum
connection for projective homogeneous varieties is isomorphic to the
pushforward D-module attached to Berenstein-Kazhdan geometric crystals.
The idea is to recognize the quantum connection as Galois and the
geometric crystal as automorphic. In particular we link the purity of
Berenstein-Kazhdan crystals to the Ramanujan property of certain Hecke
eigensheaves.
The isomorphism of D-modules comes from global rigidity results where a
Hecke eigenform is determined by its local ramification. We reveal