8–12 sept. 2025
Le Bois-Marie
Fuseau horaire Europe/Paris

On Two mod p Period Maps: Ekedahl–Oort and Fine Deligne–Lusztig Stratifications

12 sept. 2025, 09:30
1h
Centre de conférences Marilyn et James Simons (Le Bois-Marie)

Centre de conférences Marilyn et James Simons

Le Bois-Marie

35, route de Chartres 91440 Bures-sur-Yvette

Orateur

Fabrizio Andreatta (Univ. degli Studi di Milano)

Description

Consider a Shimura variety of Hodge type admitting a smooth integral model S at an odd prime $p > 3$. Consider its perfectoid cover $S(p^\infty)$ and the Hodge-Tate period map introduced by A. Caraiani and P. Scholze. We compare the pull-back to $S(p^\infty)$ of the Ekedahl-Oort stratification on the mod p special fiber of S and the pull back to $S(p^\infty)$ of the fine Deligne-Lusztig stratification on the mod p special fiber of the flag variety which is the target of the Hodge-Tate period map. If time allowa, an application to the non-emptiness of Ekedhal-Oort strata is provided.

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