l'Institut des Hautes Études Scientifiques,
le Morningside Center of Mathematics, Chinese Academy of Sciences
Organisateurs scientifiques:
Ahmed Abbes (CNRS, IHÉS),
Fabrice Orgogozo (CNRS, École polytechnique),
Takeshi Saito (Université de Tokyo),
Mercredi 13 novembre 2013 de 10h à 11h Yichao Tian (Morningside Center for Mathematics) Goren-Oort stratification and Tate cycles on Hilbert modular varieties Let B be a quaternionic algebra over a totally real field F, and p be a prime at least 3 unramified in F. We consider a Shimura variety X associated to B^* of level prime to p. A generalization of Deligne-Carayol's "modèle étrange" allows us to define an integral model for X. We will then define a Goren-Oort stratification on the characteristic p fiber of X, and show that each closed Goren-Oort stratum is an iterated P^1-fibration over another quaternionic Shimura variety in characteristic p. Now suppose that [F:Q] is even and that p is inert in F. An iteration of this construction gives rise to many algebraic cycles of middle codimension on the characteristic p fibre of Hilbert modular varieties of prime-to-p level. We show that the cohomological classes of these cycles generate a large subspace of the Tate cycles, which, in some special cases, coincides with the prediction of the Tate conjecture for the Hilbert modular variety over finite fields. This is a joint work with Liang Xiao.
Le séminaire a lieu une fois par mois (en général le deuxième mercredi)
aux lieux et heures suivants :
- IHÉS : Centre de conférences Marilyn et James Simons, horaire d'été de 10h30 à 11h30 [TU+2] ; horaire d'hiver de 10h à 11h [TU+1]. - Todai : salle 056, horaire d'été de 17h30 à 18h30 ; horaire d'hiver de 18h à 19h. - Centre Morningside : salle 110, horaire d'été de 16h30 à 17h30 ; horaire d'hiver de 17h à 18h. |