代数学コロキウム

過去の記録 ~10/22次回の予定今後の予定 10/23~

開催情報 水曜日 17:00~18:00 数理科学研究科棟(駒場) 056号室
担当者 今井 直毅, 三枝 洋一

次回の予定

2018年11月14日(水)

18:00-19:00   数理科学研究科棟(駒場) 056号室
斎藤秀司 氏 (東京大学数理科学研究科)
A motivic construction of ramification filtrations (ENGLISH)
[ 講演概要 ]
We give a new interpretation of Artin conductors of characters in the framework of theory of motives with modulus. It gives a unified way to understand Artin conductors of characters and irregularities of line bundle with integrable connections as well as overconvergent F-isocrystals of rank 1. It also gives rise to new conductors, for example, for G-torsors with G a finite flat group scheme, which specializes to the classical Artin conductor in case G = Z/nZ. We also give a motivic proof of a theorem of Kato and Matsuda on the determination of Artin conductors along divisors on smooth schemes by its restrictions to curves. Its proof is based on a motivic version of a theorem of Gabber-Katz. This is a joint work with Kay Rülling.