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On fibrations whose geometric fibers are nonreduced

Published online by Cambridge University Press:  11 January 2016

Stefan Schröer*
Affiliation:
Mathematisches Institut, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany, [email protected]
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Abstract

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We give a bound on embedding dimensions of geometric generic fibers in terms of the dimension of the base, for fibrations in positive characteristic. This generalizes the well-known fact that for fibrations over curves, the geometric generic fiber is reduced. We illustrate our results with Fermat hypersurfaces and genus 1 curves.

Keywords

Type
Research Article
Copyright
Copyright © Editorial Board of Nagoya Mathematical Journal 2010

References

[1] Ahmad, H., The algebraic closure in function fields of quadratic forms in characteristic 2, Bull. Austral. Math. Soc. 55 (1997), 293297.CrossRefGoogle Scholar
[2] Bădescu, L., Algebraic Surfaces, Universitext, Springer, New York, 2001.Google Scholar
[3] Bănică, C. and Forster, O., “Multiplicity structures on space curves” in The Lefschetz Centennial Conference, Part I (Mexico City, 1984), Contemp. Math. 58, Amer. Math. Soc., Providence, 1986, 4764.Google Scholar
[4] Bosch, S., Lütkebohmert, W., and Raynaud, M., Néron Models, Ergeb. Math. Grenzgeb. (3) 21, Springer, Berlin, 1990.Google Scholar
[5] Bourbaki, N., Algèbre commutative, Masson, Paris, 1983.Google Scholar
[6] Bourbaki, N., Algebra II, Elem. Math. (Berlin), Springer, Berlin, 1990.Google Scholar
[7] Buchweitz, R.-O., Eisenbud, D., and Herzog, J., “Cohen-Macaulay modules on quadrics” in Singularities, Representation of Algebras, and Vector Bundles, Lecture Notes in Math. 1273, Springer, Berlin, 1987, 58116.Google Scholar
[8] Drézet, J.-M., Paramétrisation des courbes multiples primitives, Adv. Geom. 7 (2007), 559612.CrossRefGoogle Scholar
[9] Grothendieck, A., Éléments de géométrie algébrique, IV: Étude locale des schémas et des morphismes de schémas, II, Publ. Math. Inst. Hautes Études Sci. 24, Springer, Heidelberg, 1965.Google Scholar
[10] Grothendieck, A., Éléments de géométrie algébrique, IV: Étude locale des schémas et des mor- phismes de schémas, III, Publ. Math. Inst. Hautes Études Sci. 28, Springer, Heidel-berg, 1966.Google Scholar
[11] Grothendieck, A., “Le groupe de Brauer III” in Dix exposés sur la cohomologie des schémas, North-Holland, Amsterdam, 1968, 88189.Google Scholar
[12] Grothendieck, A., Sections hyperplanes et projections coniques (EGA V), preprint.Google Scholar
[13] Hoffmann, D., “Diagonal forms of degree p in characteristic p 2 ” in Algebraic and Arithmetic Theory of Quadratic Forms, Contemp. Math. 344, Amer. Math. Soc., Providence, 2004, 135183.Google Scholar
[14] Hoffmann, D. and Laghribi, A., Quadratic forms and Pfister neighbors in character- istic 2, Trans. Amer. Math. Soc. 356 (2004), 40194053.CrossRefGoogle Scholar
[15] Jouanolou, J.-P., Théorèmes de Bertini et applications, Prog. Math. 42, Birkhauser, Boston, 1983.Google Scholar
[16] Kollár, J., Extremal rays on smooth threefolds, Ann. Sci. Ecole Norm. Sup. 24 (1991), 339361.CrossRefGoogle Scholar
[17] Kraft, H., Inseparable Körpererweiterungen, Comment. Math. Helv. 45 (1970), 110118.CrossRefGoogle Scholar
[18] MacLane, S., Modular fields, I: Separating transcendence bases, Duke Math. J. 5 (1939), 372393.Google Scholar
[19] Manolache, N., Multiple structures on smooth support, Math. Nachr. 167 (1994), 157202.CrossRefGoogle Scholar
[20] Matsumura, H., Commutative Algebra, 2nd ed., Math. Lecture Note Ser. 56, Benjamin/Cummings, Reading, Massachusetts, 1980.Google Scholar
[21] Mori, S. and Saito, N., Fano threefolds with wild conic bundle structures, Proc. Japan Acad. Ser. A Math. Sci. 79 (2003), 111114.CrossRefGoogle Scholar
[22] Serre, J.-P., Groupes algébriques et corps de classes, Actualités Sci. Indust. 1264, Hermann, Paris, 1975.Google Scholar
[23] Totaro, B., Birational geometry of quadrics in characteristic 2, J. Algebraic Geom. 17 (2008), 577597.CrossRefGoogle Scholar