On the homotopy exact sequence for Nori's fundamental group
arXiv:0908.0498
Abstract
Unlike Grothendieck's étale fundamental group, Nori's fundamental group does not fulfill the homotopy exact sequence in general. We give necessary and sufficient conditions which force exactness of the sequence.
Lei Zhang found a gap in the proof of Proposition 3.4. We withdraw the article, at least for the time being