Abstract
In this article we interpret the relations defining the Grothendieck-Teichmüller group \(\widehat{GT}\) as cocycle relations for certain non-commutative co-homology sets, which we compute using a result due to Brown, Serre and Scheiderer. This interpretation allows us to give a new description of the elements of \(\widehat{GT}\), as well as a new proof of the Drinfel’d-Ihara theorem stating that \(\widehat{GT}\) contains the absolute Galois group
. From the same methods we deduce other properties of \(\widehat{GT}\) analogous to known properties of
, such as the self-centralizing of the complex conjugation element.
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References
J. Birman: Braids, Links and Mapping Class Groups, Ann. of Math. Studies, Vol. 82, Princeton Univ. Press, 1975
K. Brown: Cohomology of Groups, GTM 87, Springer-Verlag, 1994
P. Deligne: Le groupe fondamental de la droite projective moins trois points. In Galois groups over ℚ, 79–298; Publ. MSRI no. 16, Springer-Verlag, 1989
V.G. Drinfel’d: On quasitriangular quasi-Hopf algebras and a group closely connected with , Leningrad Math. J. Vol. 2, No. 4, 829–860 (1991)
M. Emsalem, P. Lochak: The action of the absolute Galois group on the moduli space of spheres with four marked points, in The Grothendieck Theory of Dessins d’Enfants, London Math. Soc. Lecture Notes 200, Cambridge University Press, 1994
C. McLachlan, W. Harvey: On mapping-class groups and Teichmuller spaces, Proc. London Math. Soc. (3)30, 496–512 (1975)
D. Harbater, L. Schneps, Estimating Galois orbits of dessins, preprint
Y. Ihara: Braids, Galois groups, and some arithmetic functions, Proceedings of the ICM, Kyoto, Japan 99–120 (1990)
Y. Ihara: On the embedding of into \(\widehat{GT}\), in The Grothendieck Theory of Dessins d’Enfants, London Math. Soc. Lecture Notes 200, Cambridge Univ. Press, 1994
Y. Ihara, M. Matsumoto: On Galois Actions of Profinite Completions of Braid Groups, in Recent Developments in the Inverse Galois Problem, M. Fried et al. Eds., AMS, 1995
P. Lochak, L. Schneps: The Grothendieck-Teichmüller group and automorphisms of braid goups, in The Grothendieck Theory of Dessins d’Enfants, London Math. Soc. Lecture Notes, 200, Cambridge Univ. Press, 1994
H. Nakamura: Galois ridigity of pure sphere braid groups and profinite calculus, J. Math. Sci. Univ. Tokyo 1, 71–136 (1994)
Triangulations, Courbes Algébriques et Théorie des Champs, issue of Panoramas et Synthèses, publication of the SMF (to appear)
D. Quillen: Rational Homotopy Theory, Ann. Math. 90, 205–295 (1969)
L. Schneps: Dessins d’enfants on the Riemann sphere, in The Grothendieck Theory of Dessins d’Enfants, London Math. Soc. Lecture Notes 200, Cambridge Univ. Press, 1994
J-P. Serre: Cohomologie galoisienne, Springer Lecture Notes 5, Springer-Verlag, 1964–1994
J-P. Serre: letters (to appear)
J-P. Serre: Arbres, Amalgames, SL 2, Astérisque 46 (1977)
Revêtements étales et groupe fondamental, Springer Lecture Notes 244, Springer-Verlag (1971)
References
K.S. Brown: Cohomology of Groups. Graduate Texts in Mathematics 87, Springer, New York, 1982
J. Huebschmann: Cohomology theory of aspherical groups and of small cancellation groups. J. Pure Applied Algebra 14, 137–143 (1979)
J. Neukirch: Freie Produkte pro-endlicher Gruppen und ihre Kohomologie. Arch. Math. 22, 337–357 (1971)
C. Scheiderer: Real and Etale Cohomology. Lect. Notes Math. 1588, Springer, Berlin, 1994
C. Scheiderer: Farrell cohomology and Brown theorems for profmite groups. To appear in Manuscr. math.
C.T.C. Wall: Pairs of relative cohomological dimension one. J. Pure Applied Algebra 1, 141–154 (1971)
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Oblatum 27-XI-1995
Oblatum 19-V-1996
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Lochak, P., Schneps, L. & Scheiderer, C. A cohomological interpretation of the Grothendieck-Teichmüller group. Invent. math. 127, 571–600 (1997). https://doi.org/10.1007/s002220050131
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DOI: https://doi.org/10.1007/s002220050131