Semi-continuity for conductor divisors of étale sheaves

Abstract

In this article, we prove a semi-continuity property for both conductor divisors and logarithmic conductor divisors for étale sheaves on higher relative dimensions in a geometric situation. It generalizes a semi-continuity result for conductors of étale sheaves on relative curves to higher relative dimensions, and it can be considered as a higher dimensional $\ell$-adic analogy of André's result on the semi-continuity of Poincaré-Katz ranks of meromorphic connections on smooth relative curves.

22 pages. The article has been published in IMRN