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ALGEBRAIC AND NORI FUNDAMENTAL GERBES

Published online by Cambridge University Press:  07 July 2017

Fabio Tonini
Affiliation:
Freie Universität Berlin, FB Mathematik und Informatik, Arnimallee 3, Zimmer 112A, 14195 Berlin, Deutschland ([email protected]; [email protected])
Lei Zhang
Affiliation:
Freie Universität Berlin, FB Mathematik und Informatik, Arnimallee 3, Zimmer 112A, 14195 Berlin, Deutschland ([email protected]; [email protected])

Abstract

In this paper we extend the generalized algebraic fundamental group constructed in Esnault and Hogadi, (Trans. Amer. Math. Soc. 364(5) (2012), 2429–2442) to general fibered categories using the language of gerbes. As an application we obtain a Tannakian interpretation for the Nori fundamental gerbe defined in Borne and Vistoli (J. Algebraic Geom. (2014), S1056–3911, 00638-X) for nonsmooth non-pseudo-proper algebraic stacks.

Type
Research Article
Copyright
© Cambridge University Press 2017 

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Footnotes

This work was supported by the European Research Council (ERC) Advanced Grant 0419744101 and the Einstein Foundation.

References

Artin, M., Grothendieck, A. and Verdier, J.-L., Théorie de Topos et Cohomologie Etale des Schémas, SGA, Volume 4 (Springer, Berlin, 1963/64).Google Scholar
Berthelot, P. and Ogus, A., Notes on Crystalline Cohomology (Princeton University Press, Princeton, New Jersey, 1978).Google Scholar
Borne, N. and Vistoli, A., The Nori fundamental gerbe of a fibered category, J. Algebraic Geom. (2014), S1056–3911, 00638-X.Google Scholar
Borne, N. and Vistoli, A., Fundamental gerbes, Preprint, 2016, arXiv:1610.07341, p. 33.Google Scholar
Deligne, P., Catégories Tannakiannes, in The Grothendieck Festschrift, Vol. II, Progress in Mathematics, Volume 87, pp. 111195 (Birkhäuser Boston, Boston, MA, 1990).Google Scholar
Esnault, H. and Hogadi, A., On the algebraic fundamental group of smooth varieties in characteristic p > 0, Trans. Amer. Math. Soc. 364(5) (2012), 24292442.+0,+Trans.+Amer.+Math.+Soc.+364(5)+(2012),+2429–2442.>Google Scholar
Gieseker, D., Flat vector bundles and the fundamental group in nonzero characteristics, Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4) 2(1) (1975), 131. MR MR0382271 (52 #3156).Google Scholar
Grothendieck, A. and Raynaud, M., Revêtements Étales et Groupe Fondamental, SGA, Volume 1 (Springer, Berlin, 1971).Google Scholar
Nori, M., The fundamental group schemes, Proc. Indian Aacd. Sci. 91 (1982), 73122.Google Scholar
Saavedra, N., Catégories Tannakiennes, Lecture Notes in Mathematics, Volume 265 (Springer, Berlin, 1972).Google Scholar
Santos, dos, Fundamental group schemes for stratified sheaves, J. Algebra 317(2) (2007), 691713.Google Scholar
Tonini, F., Sheafification functors and Tannaka’s reconstruction, Preprint, 2014, arXiv:1409.4073, p. 35.Google Scholar
Tonini, F. and Zhang, L., $F$ -divided sheaves trivialized by dominant maps are essentially finite, Preprint, 2016, arXiv:1612.00208, p. 19.Google Scholar
Vistoli, A., Grothendieck topologies, fibred categories and descent theory, in Fundamental Algebraic Geometry (American Mathematical Society, Providence, RI, 2006).Google Scholar
Waterhouse, W. C., Introduction to Affine Group Schemes, Graduate Texts in Mathematics, p. 184 (Springer, Berlin, 1979).Google Scholar