Events & Seminars

2017 Dec 07

Combinatorics: Shira Zerbib Gelaki (MSRI, U. Michigan) "Colorful coverings of polytopes -- the hidden topological truth behind different colorful phenomena"

12:00pm to 1:00pm

Location: 

Room 101 in Sprinzak
Speaker: Shira Zerbib Gelaki (MSRI, University of Michigan) Title: Colorful coverings of polytopes -- the hidden topological truth behind different colorful phenomena Abstract: The topological KKMS Theorem is a powerful extension of the Brouwer's Fixed-Point Theorem, which was proved by Shapley in 1973 in the context of game theory. We prove a colorful and polytopal generalization of the KKMS Theorem, and show that our theorem implies some seemingly unrelated results in discrete geometry and combinatorics involving colorful settings.
2017 Jun 19

NT&AG: Ehud de Shalit (HUJI) "Ordinary foliations on unitary Shimura varieties"

2:00pm to 3:00pm

Abstract: Inseparable morphisms proved to be an important tool for the study of algebraic varieties in characteristic p. In particular, Rudakov-Shafarevitch, Miyaoka and Ekedahl have constructed a dictionary between "height 1" foliations in the tangent bundle and "height 1" purely inseparable quotients of a non-singular variety in characteristic p. In a joint work with Eyal Goren we use this dictionary to study the special fiber S of a unitary Shimura variety of signature (n,m), m < n, at a prime p which is inert in the underlying imaginary quadratic field. We
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 01

Number theory: Ambrus Pal (Imperial College) "Crystalline Chebotarev density theorems"

10:30am to 11:45am

Location: 

Ross Building, room 70A
I will formulate a conjectural analogue of Chebotarev's density theorem for convergent F-isocrystals over a smooth geometrically irreducible curve defined over a finite field using the Tannakian formalism. I will talk about the proof of this analogue in several special classes, including all semi-simple convergent F-isocrystals which have a filtration by isoclinic F-isocrystals of pair-wise different slopes whose monodromy groups are reductive and abelian over a non-empty open subcurve. The methods used include the theory of reductive groups and p-adic analysis,
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 1:15pm

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
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

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