Prisms and deformations of de Rham cohomology

Jun 12, 2018, 10:30 AM
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


B. Bhatt (University of Michigan)


Prisms are generalizations of perfectoid rings to a setting where "Frobenius need not be an isomorphism". I will explain the definition and use it to construct a prismatic site for any scheme. The resulting prismatic cohomology often gives a one-parameter deformation of de Rham cohomology. For instance, it recovers the recently constructed A_{inf}-cohomology for smooth schemes over perfectoid rings (and thus crystalline cohomology when in characteristic p). A relative variant yields cohomological Breuil-Kisin modules, and related ideas also give a co-ordinate free construction of q-de Rham cohomology. Joint work with Peter Scholze.

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