Abstract
Let G be a finite group, let g≥2 and g ′ ≥ 0 be integers. We introduce the algebraic stack classifying the stable curves of genus g endowed with an action of G faithful in each geometric fiber and such that the quotient of each fiber is a semi-stable curve of genus g′. We study the completion of the local rings of this algebraic stack. They are closely related to universal equivariant deformation rings R C,G of stable curves endowed with a faithful action of G. A useful tool for this purpose is a local-global principle generalizing the one obtained by Bertin and Mézard in [BM00]. We then use the results we already proved in [Mau03b] and [Mau03a] to describe some properties of the space (purity, dimension).
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Bertin, J., Mézard, A.: Déformations formelles des revêtements sauvagement ramifiés de courbes algébriques. Invent. Math. 141 (1), 195–238 (2000)
Bertin, J., Maugeais, S.: Déformation équivariante des courbes semi-stables. Ann. Inst. Fourier 55 (6), 1905–1941 (2005)
Cornelissen, G., Kato, F.: Equivariant deformation of Mumford curves and of ordinary curves in positive characteristic. Duke Math. J. 116 (3), 431–470 (2003)
Cornelissen, G., Mézard, A.: Relèvements des revêtements de courbes faiblement remifiés. arXiv:math.AG/0412189, preprint
de Jong, A.J.: Families of curves and alterations. Ann. Inst. Fourier (Grenoble) 47 (2), 599–621 (1997)
Deligne, P., Mumford, D.: The irreducibility of the space of curves of given genus. Inst. Hautes Études Sci. Publ. Math. 36, 75–109 (1969)
Ekedahl, T.: Boundary behaviour of Hurwitz schemes, The moduli space of curves (Texel Island, 1994), Progr. Math. vol. 129, Birkhäuser Boston, Boston, MA, 1995, pp. 173–198
Grothendieck, A.: Sur quelques points d'algèbre homologique. Tôhoku Math. J. 9 (2), 119–221 (1957)
Harbater, D.: Moduli of p-covers of curves. Comm. Algebra 8 (12), 1095–1122 (1980)
Liu, Q.: Algebraic geometry and arithmetic curves. Oxford University Press, 2002, Oxford Graduate Texts in Mathematics, No. 6
Maugeais, S.: Déformations équivariantes des courbes stables i, études cohomologiques, 2003, math.AG/0310137, preprint
Maugeais, S.: Relèvement des revêtements p-cycliques des courbes rationnelles semi-stables. Math. Ann. 327 (2), 365–393 (2003)
Maugeais, S.: Théorie des déformations équivariantes des morphismes localement d'intersections complètes, 2003, math.AG/0310136, preprint
Tufféry, S.: Déformations de courbes avec action de groupe. Forum Math. 5 (3), 243–259 (1993)
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Maugeais, S. Quelques résultats sur les déformations équivariantes des courbes stables. manuscripta math. 120, 53–82 (2006). https://doi.org/10.1007/s00229-006-0633-2
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DOI: https://doi.org/10.1007/s00229-006-0633-2