Cotangent bundles and micro-supports in mixed characteristic case

Abstract

For a regular scheme and its reduced closed subscheme, the latter being of finite type over a perfect field of positive characteristic, we define its cotangent bundle restricted to the closed subscheme as a family of vector bundles on smooth schemes over the field endowed with morphisms to the closed subscheme factoring through the Frobenius. For a constructible complex on the etale site of the scheme, we introduce the condition to be micro-supported on a closed conical subset in the cotangent bundle. We compute the singular supports of certain Kummer sheaves of rank 1.