Hebrew University of Jerusalem

Thu 18 Sep 2014, 3:30pm
Number Theory Seminar
room MATH 126

From Ramanujan graphs to Ramanujan complexes

room MATH 126
Thu 18 Sep 2014, 3:30pm4:30pm
Abstract
Ramanujan graphs are optimal expanders (from spectral point of view). Explicit constructions of such graphs were given in the 80's as quotients of the BruhatTits tree associated with GL(2) over a local field F, by suitable congruence subgroups. The spectral bounds were proved using works of Hecke, Deligne and Drinfeld on the "Ramanujan conjecture" in the theory of automorphic forms. The work of Lafforgue, extending Drinfeld from GL(2) to GL(n), opened the door for the construction of Ramanujan complexes as quotients of the BruhatTits buildings. This gives finite simplical complxes which on one hand are "random like" and at the same time have strong symmetries. Recently various applications have been found in combinatorics, coding theory and in relation to Gromov's overlapping properties. We will describe these developments and give some details on recent applications.
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UBC

Thu 25 Sep 2014, 3:30pm
Number Theory Seminar
room MATH 126

Primitive and doubly primitive divisors in dynamical sequences

room MATH 126
Thu 25 Sep 2014, 3:30pm4:30pm
Abstract
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Université Pierre et Marie Curie

Thu 2 Oct 2014, 3:30pm
Number Theory Seminar
room MATH 126

Points of small height on abelian varieties over function fields

room MATH 126
Thu 2 Oct 2014, 3:30pm4:30pm
Abstract
An old conjecture of Lang (for elliptic curves) generalized by Silverman, asserts that the NéronTate height of a rational point of an abelian variety defined over a number field can be bounded below linearly in terms of the Faltings height of the underlying abelian variety. We shall explore the function field analogue of this problem.
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Thu 9 Oct 2014, 3:30pm
Number Theory Seminar
room MATH 126

TBA

room MATH 126
Thu 9 Oct 2014, 3:30pm4:30pm
Abstract
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Thu 16 Oct 2014, 3:30pm
Number Theory Seminar
room MATH 126


room MATH 126
Thu 16 Oct 2014, 3:30pm4:30pm
Abstract
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SFU

Thu 23 Oct 2014, 3:30pm
Number Theory Seminar
room MATH 126

TBA

room MATH 126
Thu 23 Oct 2014, 3:30pm4:30pm
Abstract
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Emory University

Thu 30 Oct 2014, 3:30pm
Number Theory Seminar
room MATH 126

TBA

room MATH 126
Thu 30 Oct 2014, 3:30pm4:30pm
Abstract
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UBC

Thu 6 Nov 2014, 3:30pm
Number Theory Seminar
room MATH 126

TBA

room MATH 126
Thu 6 Nov 2014, 3:30pm4:30pm
Abstract
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Thu 13 Nov 2014, 3:30pm
Number Theory Seminar
room MATH 126


room MATH 126
Thu 13 Nov 2014, 3:30pm4:30pm
Abstract
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Thu 20 Nov 2014, 3:30pm
Number Theory Seminar
room MATH 126


room MATH 126
Thu 20 Nov 2014, 3:30pm4:30pm
Abstract
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Thu 27 Nov 2014, 3:30pm
Number Theory Seminar
room MATH 126


room MATH 126
Thu 27 Nov 2014, 3:30pm4:30pm
Abstract
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