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 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
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
2016 Feb 15

Number theory: Andrey Levin (Moscow) "Kronecker double series at CM points and dilogarithm"

2:00pm to 3:00pm

Location: 

Ross building, 70A
This talk is in natural in the context of the Zagier conjecture. We express values of the Kronecker double series at CM points in terms of values some version (Bloch-Wigner) of dilogarithm in algebraic numbers. As zeta-function of the Hilbert class field of quadratic field can be expressed as combination of the Kronecker double series at CM points my result gives explicit form of the Zagier conjecture. My technique is rather elementary and the proof is based on the introduction some new function (elliptic (1,1)-logarithm) and comparisons with it.
2018 Jan 01

NT&AG: Efrat Bank (University of Michigan), "Correlation between primes in short intervals on curves over finite fields"

2:00pm to 3:00pm

Location: 

Room 70A, Ross Building, Jerusalem, Israel
In this talk, I present an analogue of the Hardy-Littlewood conjecture on the asymptotic distribution of prime constellations in the setting of short intervals in function fields of smooth projective curves over finite fields. I will discuss the definition of a "short interval" on a curve as an additive translation of the space of global sections of a sufficiently positive divisor E by a suitable rational function f, and show how this definition generalizes the definition of a short interval in the polynomial setting.
2016 Nov 21

NT&AG: Damaris Schindler (Utrecht University), "Systems of quadratic forms"

2:00pm to 3:00pm

Location: 

Ros Building, 70A
In this talk we discuss some aspects concerning the arithmetic of systems of quadratic forms. This includes a result on the frequency of counterexamples to the Hasse principle for del Pezzo surfaces of degree four (joint work with J. Jahnel), and a result on the representability of integers by systems of three quadratic forms (joint work with L. B. Pierce and M. M. Wood).
2017 Feb 27

NT&AG: Eyal Goren (McGill University), "p-adic dynamics of Hecke operators"

3:00pm to 4:00pm

Location: 

Ross 70A
Abstract: Motivated by understanding the action of Hecke operators on special sub-varieties of Shimura varieties, we consider the simplest possible case: the action of Hecke operators on the j-line, namely on the moduli space of elliptic curves, and in particular the action on singular moduli. Our interest is in this action considered in the p-adic topology. The emerging picture is surprisingly rich and the answers involve Serre-Tate coordinates, the Gross-Hopkins period map and finally involves random walks on GL_n. This is joint work with Payman Kassaei (King's College).
2017 Dec 25

NG&AT: Zev Rosengarten (Stanford University), "Tamagawa Numbers of Linear Algebraic Groups Over Function Fields"

2:00pm to 3:00pm

Location: 

Room 70A, Ross Building, Jerusalem, Israel
Abstract: In 1981, Sansuc obtained a formula for Tamagawa numbers of reductive groups over number fields, modulo some then unknown results on the arithmetic of simply connected groups which have since been proven, particularly Weil's conjecture on Tamagawa numbers over number fields. One easily deduces that this same formula holds for all linear algebraic groups over number fields. Sansuc's method still works to treat reductive groups in the function field setting, thanks to the recent resolution of Weil's conjecture in the function field setting by Lurie and Gaitsgory.
2016 Jun 02

Number theory: Eran Asaf (HUJI) "Invariant norms in representations of GL_2(Q_p)"

12:00pm to 1:15pm

Location: 

Hebrew University, Givat Ram, Ross Building, room 63
A natural question is whether there exists a continuous p-adic analogue for the classical local Langlands correspondence for GL_n(F) . Namely, for a finite extension F of Q_p, we want to associate continuous p -adic representations of GL_n(F) to n-dimensional p-adic representations of the Weil group of F. The particular case, where F=Q_p and n=2 , is now known. One of the main tools for establishing this correspondence was the existence of GL_2(Q_p)-invariant norms in certain representations of GL_2(Q_p).
2017 Jan 02

NT&AG: Ehud de Shalit (HUJI), "Geometry modulo p of some unitary Shimura varieties"

2:00pm to 3:00pm

Location: 

Ros Building, 70A
Abstract: This talk will be about joint work with Eyal Goren about the structure of Picard modular surfaces at a prime p which is inert in the underlying quadratic imaginary field. The main tool for studying the bad reduction of Shimura varieties is the theory of local models (due to de Jong and Rapoport-Zink). Our results concern global geometric questions which go beyond the theory of global models. For example, we are able to count supersingular curves on the Picard surface. We also study certain foliations in its tangent bundle that have not been studied before, and

Pages