Galois Covers and the Hilbert-Grunwald Property
[Revêtements galoisiens et propriété de Hilbert-Grunwald]
Dèbes, Pierre ; Ghazi, Nour
Annales de l'Institut Fourier, Tome 62 (2012), p. 989-1013 / Harvested from Numdam

Notre résultat principal mêle plusieurs thèmes  : il contient une conclusion de type Grunwald-Wang, une version du théorème d’irréductibilité de Hilbert et une forme p-adique à la Harbater, mais avec bonne réduction, du problème inverse de Galois sous sa forme régulière (RIGP). Nous en déduisons un énoncé qui pose de nouvelles questions sur le RIGP sur . La stratégie générale est d’étudier et d’exploiter la bonne réduction de certains modèles tordus de revêtements et des espaces de modules associés.

Our main result combines three topics: it contains a Grunwald-Wang type conclusion, a version of Hilbert’s irreducibility theorem and a p-adic form à la Harbater, but with good reduction, of the Regular Inverse Galois Problem. As a consequence we obtain a statement that questions the RIGP over . The general strategy is to study and exploit the good reduction of certain twisted models of the covers and of the associated moduli spaces.

Publié le : 2012-01-01
DOI : https://doi.org/10.5802/aif.2714
Classification:  14H30,  11R32,  12F12,  12E25,  14Gxx,  14Dxx,  14H10
Mots clés: théorie inverse de Galois, problème de Grunwald, théorème d’irréductibilité de Hilbert, revêtements algébriques, corsp locaux, corps globaux, espaces de Hurwitz
@article{AIF_2012__62_3_989_0,
     author = {D\`ebes, Pierre and Ghazi, Nour},
     title = {Galois Covers and  the Hilbert-Grunwald Property},
     journal = {Annales de l'Institut Fourier},
     volume = {62},
     year = {2012},
     pages = {989-1013},
     doi = {10.5802/aif.2714},
     zbl = {1255.14022},
     mrnumber = {3013814},
     language = {en},
     url = {http://dml.mathdoc.fr/item/AIF_2012__62_3_989_0}
}
Dèbes, Pierre; Ghazi, Nour. Galois Covers and  the Hilbert-Grunwald Property. Annales de l'Institut Fourier, Tome 62 (2012) pp. 989-1013. doi : 10.5802/aif.2714. http://gdmltest.u-ga.fr/item/AIF_2012__62_3_989_0/

[1] Artin, Michael; Grothendieck, Alexandre; Verdier, Jean.-Louis SGA 4 Théorie des Topos et Cohomologie Étale des Schémas, Springer, LNM, Tome 269, 270, 305 (1973) | MR 354654

[2] Beckmann, Sybilla On extensions of number fields obtained by specializing branched coverings, J. Reine Angew. Math., Tome 419 (1991), pp. 27-53 | MR 1116916 | Zbl 0721.11052

[3] Dèbes, Pierre Covers of P 1 over the p-adics, Recent developments in the Inverse Galois Problem, Cambridge University Press (Contemporary Math.) Tome 186 (1995), pp. 217-238 | MR 1352273 | Zbl 0856.12004

[4] Dèbes, Pierre Galois covers with prescribed fibers: the Beckmann-Black problem, Ann. Scuola Norm. Sup. Pisa, Cl. Sci. (4), Tome 28 (1999), pp. 273-286 | Numdam | MR 1736229 | Zbl 0954.12002

[5] Dèbes, Pierre Some arithmetic properties of algebraic covers, Aspects of Galois Theory, Cambridge University Press (London Math. Soc. Lecture Note Series) Tome 256 (1999), pp. 66-84 | MR 1708602 | Zbl 0977.14009

[6] Dèbes, Pierre Théorème d’existence de Riemann, Arithmétique des revêtements algébriques, SMF (Séminaires et Congrès) Tome 5 (2001), pp. 27-41 | MR 1924915 | Zbl 1037.12007

[7] Dèbes, Pierre Arithmétique des revêtements de la droite, Lecture Notes 2009/10 (2009) (http://math.univ-lille1.fr/~pde/ens.html)

[8] Dèbes, Pierre; Douai, Jean-Claude Algebraic covers: field of moduli versus field of definition, Annales Sci. E.N.S., Tome 30 (1997), pp. 303-338 | Numdam | MR 1443489 | Zbl 0906.12001

[9] Dèbes, Pierre; Douai, Jean-Claude; Moret-Bailly, Laurent Descent Varieties for Algebraic Covers, J. Reine Angew. Math., Tome 574 (2004), pp. 51-78 | Article | MR 2099109 | Zbl 1077.14019

[10] Dèbes, Pierre; Emsalem, Michel Harbater-Mumford Components and Hurwitz Towers, J. Math. Inst. Jussieu, Tome 5 (2006) no. 3, pp. 351-371 | Article | MR 2243760

[11] Dèbes, Pierre; Ghazi, Nour Specializations of Galois Covers of the line, Alexandru Myller Mathematical Seminar, Proceedings of the Centennial Conference, V. Barbu and O. Carja, Eds (American Institute of Physics) Tome 1329 (2011), pp. 98-108 | MR 2752504

[12] Dèbes, Pierre; Walkowiak, Yann Bounds for Hilbert’s Irreducibility Theorem, Pure & Applied Math. Quarterly, Tome 4/4 (2008), pp. 1059-1083 | MR 2441693

[13] Deligne, Pierre La conjecture de Weil I, Publ. Math. IHES, Tome 43 (1974), pp. 273-308 | Numdam | MR 340258 | Zbl 0287.14001

[14] Deligne, Pierre La conjecture de Weil II, Publ. Math. IHES, Tome 52 (1980), pp. 137-252 | Numdam | MR 601520 | Zbl 0456.14014

[15] Deschamps, Bruno Existence de points p-adiques pour tout p sur un espace de Hurwitz, Recent developments in the Inverse Galois Problem, Cambridge University Press (Contemporary Math.) Tome 186 (1995), pp. 239-247 | MR 1352274 | Zbl 0838.14019

[16] Eichler, Martin Zum Hilbertschen Irreduzibilittssatz, Math. Ann., Tome 116 (1939), pp. 742-748 | Article | MR 1513256 | Zbl 0021.00705

[17] Ekedahl, Torsten An effective version of Hilbert’s irreducibility theorem, Séminaire de Théorie des Nombres, Paris 1988/1989, Birkhäuser (Progress in Mathematics) Tome 91 (1990), pp. 241-248 | MR 1104709 | Zbl 0729.12005

[18] Fried, Michael D. On Hilbert’s irreducibility theorem, J. Number Theory, Tome 6 (1974), pp. 211-231 | Article | MR 349624 | Zbl 0299.12002

[19] Fried, Michael D. Introduction to modular towers: generalizing dihedral group–modular curve connections, Recent developments in the inverse Galois problem, Amer. Math. Soc., Providence, RI (Contemp. Math.) Tome 186 (1995), pp. 111-171 | MR 1352270 | Zbl 0957.11047

[20] Fried, Michael D.; Völklein, Helmut The inverse Galois problem and rational points on moduli spaces, Math. Ann., Tome 290 (1991) no. 4, pp. 771-800 | Article | MR 1119950 | Zbl 0763.12004

[21] Fulton, William Hurwitz schemes and irreducibility of moduli of algebraic curves, Ann. of Math. (2), Tome 90 (1969), pp. 542-575 | Article | MR 260752 | Zbl 0194.21901

[22] Grothendieck, A. Éléments de géométrie algébrique. IV. Étude locale des schémas et des morphismes de schémas IV, Inst. Hautes Études Sci. Publ. Math. (1967) no. 32, pp. 361 | Numdam | MR 238860 | Zbl 0144.19904

[23] Grothendieck, Alexandre Revêtements étales et groupe fondamental, Springer, LNM, Tome 224 (1971) | MR 354651

[24] Grothendieck, Alexandre SGA 5 Cohomologie -adique et Fonctions L , Springer-Verlag, LNM, Tome 589 (1973) | MR 354654

[25] Grothendieck, Alexandre; Murre, Jacob P. The Tame Fundamental Group of a Formal Neighbourhood of a Divisor with Normal Crossings on a Scheme, Springer, LNM, Tome 208 (1971) | MR 316453 | Zbl 0216.33001

[26] Harbater, David Galois coverings of the arithmetic line, Lecture Notes in Math., Tome 1240 (1987), pp. 165-195 | Article | MR 894511 | Zbl 0627.12015

[27] Jordan, Camille Recherches sur les substitutions, J. Liouville, Tome 17 (1872), pp. 351-367

[28] Lagarias, J. C.; Montgomery, H. L.; Odlyzko, A. M. A Bound for the Least Prime Ideal in the Chebotarev Density Theorem, Invent. Math., Tome 54 (1979), pp. 271-296 | Article | MR 553223 | Zbl 0401.12014

[29] Lagarias, J. C.; Odlyzko, A. M. Effective versions of the Chebotarev Density Theorem, Algebraic Number Fields, Academic Press, New-York ((A. Fröhlich edit.) (1977), pp. 409-464 | MR 447191 | Zbl 0362.12011

[30] Milne, James S. Etale Cohomology, Princeton University Press, Princeton Mathematical Series, Tome 33 (1980) | MR 559531 | Zbl 0433.14012

[31] Moret-Bailly, Laurent Groupes de Picard et problèmes de Skolem II, Annales Sci. E.N.S., Tome 22 (1989), pp. 181-194 | Numdam | MR 1005158 | Zbl 0704.14015

[32] Moret-Bailly, Laurent Problèmes de Skolem sur les champs algébriques, Comp. Math., Tome 125 (2001), pp. 1-30 | Article | MR 1818054

[33] Neukirch, Jürgen On solvable number fields, Invent. Math., Tome 53 (1979) no. 2, pp. 135-164 | Article | MR 560411 | Zbl 0447.12008

[34] Neukirch, Jürgen; Schmidt, Alexander; Wingberg, Kay Cohomology of number fields, Springer-Verlag, Berlin, Grundlehren der Mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences], Tome 323 (2008) | MR 2392026

[35] Plans, Bernat; Vila, Nuria Galois covers of P 1 over Q with prescribed local or global behavior by specialization, J. Théorie des Nombres Bordeaux, Tome 17 (2005), pp. 271-282 | Article | Numdam | MR 2152224

[36] Pop, Florian Embedding problems over large fields, Annals of Math., Tome 144 (1996), pp. 1-35 | Article | MR 1405941 | Zbl 0862.12003

[37] Saltmann, David J. Generic Galois extensions and Problems in Field Theory, Advances in Math., Tome 43 (1982), pp. 250-283 | Article | MR 648801 | Zbl 0484.12004

[38] Serre, Jean-Pierre Quelques applications du théorème de densité de Chebotarev, Pub. Math. I.H.E.S., Tome 54 (1981), pp. 323-401 | Numdam | MR 644559 | Zbl 0496.12011

[39] Serre, Jean-Pierre Topics in Galois Theory, Jones and Bartlett Publishers, Research Notes in Mathematics (1992) | MR 1162313 | Zbl 0746.12001

[40] Wewers, Stefan Construction of Hurwitz spaces, Essen (1998) (Ph. D. Thesis) | Zbl 0925.14002