报告题目：Purity and torsors over Prüfer bases

报告人：郭宁，Euler International Mathematical Institute (Russia)

时间：2023年7月30日（周日），14：30-15：30

地点：第二教学楼 2104

摘要：In algebraic geometry, purity refers to a diverse range of phenomena in which certain invariants or categories associated to geometric objects are insensitive to the removal of closed subsets of large codimension. In this talk, we present Zariski—Nagata purity concerning finite étale covers on smooth schemes over Prüfer rings by proving Auslander’s flatness criterion in this non-Noetherian context. By Gabber—Ramero’s upper bound of projective dimensions, we present an Auslander—Buchsbaum formula. Finally, we take advantage of these cohomological results to establish the parafactoriality of schemes and the purity of torsors over Prüfer bases. This is a joint work with Fei Liu.