A Lefschetz principle in non-archimedean geometry -- Brian Conrad, September 12, 2014

In analytic geometry over a non-archimedean field it is often convenient to work over a ground field that is algebraically closed, but that can create some difficulties because such fields have non-noetherian valuation ring. We explain a technique based on deformation theory and formal algebraic spaces to reduce certain problems in relative non-archimedean geometry to the case of a discretely-valued ground field, and give an application to de Rham cohomology, answering a question of Scholze. This is joint work with O. Gabber.