Number theory seminar

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Spring Semester 2011

Date / Time

Speaker

Title

Location

25 February 2011
14:15-15:15

Dr. Harald Helfgott
ENS Paris / Bristol

Event Details

Number Theory Seminar

Title	Three-term arithmetic progressions in the primes
Speaker, Affiliation	Dr. Harald Helfgott, ENS Paris / Bristol
Date, Time	25 February 2011, 14:15-15:15
Location	HG G 43

Three-term arithmetic progressions in the primes

HG G 43

11 March 2011
14:15-15:15

Jacob Tsimerman
Princeton University

Event Details

Number Theory Seminar

Title	Constructing Abelian Varieties over the Algebraic Closure of the Rationals Not Isogenous to a Jacobian
Speaker, Affiliation	Jacob Tsimerman, Princeton University
Date, Time	11 March 2011, 14:15-15:15
Location	HG G 43
Abstract	We discuss the following question of Nick Katz and Frans Oort: Given an Algebraically closed field $K$, is there an Abelian variety over $K$ of dimension $g$ which is not isogenous to a Jacobian? For $K$ the complex numbers, it is easy to see that the answer is "yes" for $g>3$ using measure theory, but over a countable field like $\bar{\mathbf{Q}}$, new methods are required. Building on work of Chai-Oort, we show that, as expected, such Abelian varieties exist for $K=\bar{\mathbf{Q}}$ and $g>3$ . We will explain the proof as well as its connection to the Andr\'e-Oort conjecture.

Constructing Abelian Varieties over the Algebraic Closure of the Rationals Not Isogenous to a Jacobianread_more

HG G 43

18 March 2011
14:15-15:15

Prof. Dr. Andrej Dujella
University of Zagreb

Event Details

Number Theory Seminar

Title	High rank elliptic curves and applications
Speaker, Affiliation	Prof. Dr. Andrej Dujella, University of Zagreb
Date, Time	18 March 2011, 14:15-15:15
Location	HG G 43

High rank elliptic curves and applications

HG G 43

25 March 2011
14:15-15:15

Prof. Dr. Bruno Klingler
Université Paris 7

Event Details

Number Theory Seminar

Title	On rigidity for complex hyperbolic lattices
Speaker, Affiliation	Prof. Dr. Bruno Klingler, Université Paris 7
Date, Time	25 March 2011, 14:15-15:15
Location	HG G 43
Abstract	I will explain how rigidity problems for complex hyperbolic lattices (i.e. discrete subgroups with finite covolume of an Hermitian group U(n,1)) lead to interesting questions in Hodge theory and automorphic forms, and provide an answer for some of them.

On rigidity for complex hyperbolic latticesread_more

HG G 43

8 April 2011
14:15-15:15

Prof. Dr. Nicolas Bergeron
Université Pierre et Marie Curie

Event Details

Number Theory Seminar

Title	Special cycles and cohomology of certain arithmetic manifolds
Speaker, Affiliation	Prof. Dr. Nicolas Bergeron, Université Pierre et Marie Curie
Date, Time	8 April 2011, 14:15-15:15
Location	HG G 43
Abstract	In a joint work with John Millson and Colette Moeglin we show that special cycles generate a large part of the cohomology of locally symmetric spaces associated to orthogonal groups. We prove in particular that classes of totally geodesic submanifolds generate the cohomology groups of degree n of compact congruence p-dimensional hyperbolic manifolds "of simple type" as long as n is strictly smaller than (p-2)/4. We also prove that for connected Shimura varieties associated to O(p,2) the Hodge conjecture is true for classes of degree <(p-1)/4. I will explain the strategy of the proof.

Special cycles and cohomology of certain arithmetic manifoldsread_more

HG G 43

15 April 2011
14:15-15:15

Prof. Dr. Yuri Bilu
Université Bordeaux I

Event Details

Number Theory Seminar

Title	Rational points on modular curves
Speaker, Affiliation	Prof. Dr. Yuri Bilu, Université Bordeaux I
Date, Time	15 April 2011, 14:15-15:15
Location	HG G 43

Rational points on modular curves

HG G 43

6 May 2011

Event Details

Number Theory Seminar

Title	ETH Number Theory Days 2011
Speaker, Affiliation
Date, Time	6 May 2011,
Location	EPF Lausanne

ETH Number Theory Days 2011

EPF Lausanne

7 May 2011

Event Details

Number Theory Seminar

Title	ETH Number Theory Days 2011
Speaker, Affiliation
Date, Time	7 May 2011,
Location	EPF Lausanne

ETH Number Theory Days 2011

EPF Lausanne

27 May 2011
14:15-15:15

Prof. Dr. Kunrui Yu
Hong Kong University of Science and Technology

Event Details

Number Theory Seminar

Title	p-adic Logarithmic Forms and a Problem of Erdös
Speaker, Affiliation	Prof. Dr. Kunrui Yu, Hong Kong University of Science and Technology
Date, Time	27 May 2011, 14:15-15:15
Location	HG G 43

p-adic Logarithmic Forms and a Problem of Erdös

HG G 43

Organizers: Clemens Fuchs, Özlem Imamoglu, Emmanuel Kowalski, Richard Pink, Gisbert Wüstholz

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