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Current interests

Group cohomology, Galois theory, finite groups in general, dessins d'enfants.

Here's my CV, in English.

Computer calculations

a database of dessins and their Belyi maps.

Witt-invariants for links (joint with Gael Collinet).

Stiefel-Whitney classes, Chern classes and Steenrod operations for some 2-groups.


21. (with N. Gill and M. Liebeck) The binary actions of simple groups of Lie type of characteristic 2, to appear. Arxiv

20. (with N. Gill) The binary actions of simple groups with a single conjugacy class of involutions, to appear. Arxiv

19. (with N. Gill) The binary actions of alternating groups, to appear. Arxiv

18. Homogeneous coherent configurations from spherical buildings and other edge-coloured graphs,
Graphs Combin. 38 (2022), no. 3. Arxiv

17. (with J. Minac) Extensions of unipotent groups, Massey products and Galois theory,
Adv. Math. vol 354, 2019. Arxiv Journal

16. (with J. Minac and A. Topaz; appendix by Wittenberg) Four-fold Massey products in Galois cohomology,
Compos. Math. vol 154 (9), 2018. Arxiv Journal

15. The Grothendieck-Teichmüller group of PSL(2,q),
J. Group Theory vol 21 (2), 2018. Arxiv SMC script 1 SMC script 2 Journal

14. Cayley graphs and automatic sequences,
Journal of Algebraic Combinatorics, vol 45 (1), 2017. Arxiv Journal

13. The Grothendieck-Teichmüller group of a finite group and G-dessins d'enfants,
Symmetry in Graphs, Maps and Polytopes, Springer Proc. Math. Stat. vol 159, 2016. Arxiv SMC script 1 SMC script 2

12. An elementary approach to dessins d'enfants and the Grothendieck-Teichmüller group,
Enseign. Math. vol 60, 2014. Arxiv Journal

11. Examples of Sweedler cohomology in positive characteristic,
Comm. Alg., vol 43 (5), 2015. Arxiv Journal

10. (with J. Minac) Milnor K-theory and the graded representation ring,
Journal of K-Theory, vol 13 (3), 2014. Arxiv Journal

9. (with G. Collinet) A link invariant with values in the Witt ring,
Quantum Topol. vol 5 (3), 2014. Arxiv Sage script Journal

8. (with C. Kassel and A. Masuoka) Twisting algebras using non-commutative torsors,
Math. Zeit. vol 271 (3), 2012. Arxiv Journal

7. (with C. Kassel) Cohomology of invariant Drinfeld twists on group algebras,
Int. Math. Res. Not. vol 2010, 2010. Arxiv Journal

6. The computation of Stiefel-Whitney classes,
Ann. Inst. Fourier vol 59, 2009. Arxiv Journal.

5. Geometric methods for cohomological invariants,
Doc. Math. vol 12, 2007. Arxiv Journal

4. The representation ring of a simply connected Lie group as a lambda-ring,
Comm. Algebra vol 35 (3), 2007. Arxiv Journal

3. The Chow rings of G2 and Spin(7),
J. reine angewand. Math. vol 604, 2007. Arxiv Journal Addendum

2. Steenrod operations on the Chow ring of a classifying space,
Adv. Math. vol 196 (2), 2005. Arxiv Journal

1. Chow rings and cobordism of some Chevalley groups,
Math. Proc. Cam. Phil. Soc. vol 136 (3), 2004. Arxiv Journal

These were all refereed, or will be at some point.


Leçons sur l'homologie et le groupe fondamental,
Cours Spécialisés, 29. Société Mathématique de France, Paris, 2022.
A gentle introduction to local class field theory,
Cambridge University Press, Cambridge, 2018. MathSciNet Google books


Not intended for publication

Survey on the theory of beta-rings: Adams operations in cohomotopy. Arxiv

A paper (with Y. Ségalat) containing known, but hard to find, results: Not so new congruences for Stirling numbers of the first kind, with an application to Chern classes, Arxiv

Documents needed to get a degree

Habilitation à diriger les recherches.

PhD Thesis : Algebraic cycles, cobordism, and the cohomology of classifying spaces PDF