报告人：Takeshi Saito斋藤毅（东京大学）

题  目：Characteristic cycle of an l-adic sheaf

时  间：2019.09.04（星期三），09:45-10 :45

地  点：数学院南楼N202室

摘  要：For an l-adic sheaf on a smooth variety over a perfect field of characteristic p >= 0, its characteristic cycle is defined as a cycle supported on the singular support, defined by Beilinson as a conical closed subset of the cotangent bundle of the variety. This is an algebraic analogue of that constructed by Kashiwara-Schapira in a transcendental setting.
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报告人：Takeshi Saito斋藤毅（东京大学）

题  目：Ramification groups of a local field (with Ahmed Abbes and Kazuya Kato)

时  间：2019.09.05（星期四），10:00-11:30

地  点：数学院南楼N202室

摘  要：For a Galois extension of a discrete valuation field with not necessarily perfect residue field, two filtrations (logarithmic and non-logarithmic) by ramification groups are defined by a geometric method by Abbes and myself. For an abelian extension, another filtration is defined earlier by Kato by a cohomological method. After briefly recalling the definition, we discuss a recent result with Kato on the equality of Kato's filtration with the logarithmic filtration.