Number Theory & Algebraic Geometry

The Number Theory and Algebraic Geometry seminar meets on Mondays at 14:00 at room 70 in the Ross Building.
2020 Dec 21

AG & NT lunch: Gil Livneh "Purely Inseparable Galois Morphisms and Smooth Foliations"

1:00pm to 2:00pm


Abstract: Inseparable extensions and morphisms are an important feature in positive characteristic. The study of these uses (smooth) foliations in the tangent bundle of derivations, as was first seen in a theorem of Jacobson (1944) on purely inseparable field extensions of exponent 1. In this talk we will state Jacobson's theorem and some of its generalizations: to normal domains, to regular local and non-local rings, and to morphisms of smooth varieties.
2020 Dec 07

AG & NT Lunch: Zev Rosengarten "Unipotent groups over imperfect fields"

1:00pm to 2:00pm

Abstract: Unipotent groups form one of the fundamental building blocks in the theory of linear algebraic groups. Over perfect fields, their behavior is very simple. But over imperfect fields, the situation is much more complicated. We will discuss various aspects of these groups, from the fundamental theory to a study of their Picard groups, which appear to play a central role in understanding their behavior. 










2020 Nov 16

AG & NT lunch seminar: José Ibrahim Villanueva Gutiérrez, "Iwasawa main conjecture"

1:00pm to 2:00pm

Speaker:   José Ibrahim Villanueva Gutiérrez

Title:  "Iwasawa main conjecture"

Abstract: Iwasawa main conjecture, which is actually a theorem (Mazur & Wiles
84), fulfills the relations between arithmetic objects, p-adic L-functions and complex 
L-functions. In this talk we sketch how these relations arise and give some consequences.


https://huji.zoom.us/j/85259021329?pwd=RndGa0VNRjFMQ3hXYkJRb1k5ZGFkQT09
2020 Apr 27

Spencer Leslie [HUJI-BGU AGNT Seminar]

2:15pm to 4:00pm

Location: 

https://zoom.us/j/468718180,
Speaker: Spencer Leslie (Duke)
Title: The endoscopic fundamental lemma for unitary symmetric spaces
Abstract: Motivated by the study of certain cycles in locally symmetric
spaces and periods of automorphic forms on unitary groups, I propose a
theory of endoscopy for certain symmetric spaces. The main result is the
fundamental lemma for the unit function. After explaining where the
fundamental lemma fits into this broader picture, I will describe its
proof.
Join Zoom Meeting
2020 Mar 16

NT Seminar - Sam Chow - CANCELLED!!!

2:30pm to 3:30pm

Location: 

Ross 70

Title. Dyadic approximation in the Cantor set

Abstract. We investigate the approximation rate of a typical element of the Cantor set by dyadic rationals. This is a manifestation of the times two times three phenomenon, and is joint work with Demi Allen and Han Yu.
2019 Dec 30

NT Seminar - Shai Evra

2:30pm to 3:30pm

Location: 

Ross 70

Title: Ramanujan Conjectures, Density Hypotheses and Applications for Arithmetic Groups.
Abstract: The Generalized Ramanujan Conjecture (GRC) for GL(n) is a central open problem in modern number theory. Its resolution is known to yield applications in many fields, such as: Diophantine approximation and arithmetic groups. For instance, Deligne's proof of the Ramanujan-Petersson conjecture for GL(2) was a key ingredient in the work of Lubotzky, Phillips and Sarnak on Ramanujan graphs.
2019 Dec 23

NT Seminar - Uriya First

2:30pm to 3:30pm

Location: 

Ross 70
Title: The Grothendieck--Serre conjecture for classical groups in low dimensions
Abstract:
A famous conjecture of Grothendieck and Serre predicts that if G is a reductive group scheme over a semilocal regular domain R and X is a G-torsor, then X has a point over the fraction field of R if and only if it has an R-point. Many instances of the conjecture have been established over the years. Most notably, Panin and Fedorov--Panin proved the conjecture when R contains a field.
2020 Jan 06

Special Seminar - Frauke Bleher

4:00pm to 5:00pm

Location: 

Ross 63
Title: Cup products oncurves over finite fields
Abstract: This is joint work with Ted Chinburg.
Let C be a smooth projective curve over a finite field k, and
let l be a prime number different from the characteristic of k.
In this talk I will discuss triple cup products on the first etale
cohomology group of C with coefficients in the constant
sheaf of l-th roots of unity. These cup products are important
for finding explicit descriptions of the l-adic completion of the
etale fundamental group of C and also for cryptographic
2019 Dec 09

NT Seminar - Eyal Kaplan

2:30pm to 3:30pm

Location: 

Ross 70

Title: The generalized doublingmethod and its applications
Abstract: The doubling method,first introduced by Piatetski-Shapiro and Rallis in the 80s, has had numerousapplications, e.g. to the theta correspondence and to arithmetic problems.In a series of recent works this method was generalized in severalaspects, with an application to functoriality from classical groups to GL(N).The most recent result is a multiplicityone theorem (joint work with Gourevitch and Aizenbud).
I will brieflysurvey the method and talk about some of its applications.

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