Lecture----数学院晨兴数学中心

Title:	Semisimplicity of geometric monodromy on etale cohomology.
Speaker:	Akio Tamagawa (RIMS, Kyoto University)
Time:	2016-4-13, 16:30-17:30
Place:	110
Abstract:	Let K be a function field over an algebraically closed field of characteritic p \geq 0, X a proper smooth K-scheme, and l a prime distinct from p. Deligne proved that the Q_l-coefficient etale cohomology groups of the geometric fiber of X --> K are always semisimple as G_K-modules. In this talk, we consider a similar problem for the F_l-coefficient etale cohomology groups. Among other things, we show that if p=0 (resp. in general), they are semisimple for all but finitely many l's (resp. for all l's in a set of density 1).
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