Independence of ℓ and traces on cohomology.

Olsson, Martin · Proc Natl Acad Sci U S A · 2016

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Abstract

Let k be an algebraically closed field, and let [Formula: see text] be an endomorphism of a separated scheme of finite type over k We show that for any [Formula: see text] invertible in k, the alternating sum of traces [Formula: see text] of pullback on étale cohomology is a rational number independent of [Formula: see text] This is deduced from a more general result for motivic sheaves.