The Overconvergent Site I. Coefficients

Abstract

We define and study the overconvergent site of an algebraic variety, the sheaf of overconvergent functions on this site and show that the modules of finite presentations correspond to Berthelot's overconvergent isocrystals. We work with Berkovich theory instead of rigid analytic geometry and do not use any of Berthelot's results. This gives a complete alternative approach to rigid cohomology.