A smooth counterexample to Nori’s conjecture on the fundamental group scheme

Pauly, Christian

doi:10.1090/S0002-9939-07-08805-3

A smooth counterexample to Nori’s conjecture on the fundamental group scheme
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by Christian Pauly PDF

Proc. Amer. Math. Soc. 135 (2007), 2707-2711 Request permission

Abstract:

We show that Nori’s fundamental group scheme $\pi (X,x)$ does not base change correctly under extension of the base field for certain smooth projective ordinary curves $X$ of genus $2$ defined over a field of characteristic $2$.

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