Clément Legrand – Duchesne

I am a third year PhD student at LaBRI in Bordeaux. You might be looking for Clément Legrand – Lixon who studied at ENS Rennes at the same time as me.

I am broadly interested in combinatorics and graph theory, with a special fondness for reconfiguration and problems with a geometric flavor. In particular, a significant part of my work focuses on colorings and Kempe changes. My supervisors are Marthe Bonamy and Vincent Delecroix and I am a member of the teams Graphes et Optimisations and Combinatoire et Interactions.

Publications, conferences and Workshops


  • Minimum Separator Reconfiguration , arXiv:2307.07782, IPEC 23, with Guilherme C. M. Gomes, Reem Mahmoud, Amer E. Mouawad, Yoshio Okamoto, Vinicius F. dos Santos and Tom C. van der Zanden.
  • The structure of quasi-transitive graphs avoiding a minor with applications to the domino problem, arXiv:2304.01823, Eurocomb23 and submitted to JCTb, with Louis Esperet and Ugo Giocanti.
  • Recoloring version of Hadwiger's conjecture, arXiv:2103.10684, Eurocomb23 and JCTb, with Marthe Bonamy, Marc Heinrich and Jonathan Narboni.
  • Strengthening a theorem of Meyniel, arXiv:2201.07595, SIAM journal on discrete mathematics, with Quentin Deschamps, Carl Feghali, František Kardoš and Théo Pierron.
  • Kempe changes in degenerate graphs, arXiv:2112.02313, European Journal of Combinatorics, with Marthe Bonamy and Vincent Delecroix.
  • Parameterized complexity of untangling knots, arXiv:2111.05001, ICALP 2022 and SICOMP, with Ashutosh Rai and Martin Tancer.
  • Kempe changes in bounded treewidth graphs, Eurocomb21, with Marthe Bonamy and Vincent Delecroix.

Workshops and contributed talks

  • Invited speaker at JCB 2024
  • Random embedding of bounded degree trees:
    • Lyon Graph seminar (December 12, 2023)
    • Grenoble Graph seminar (December 7, 2023)
    • JGA 2023 (November 22, 2023)
  • Reconfiguration of square-tiled surfaces:
    • Luxembourg Geometry seminar (November 13, 2023)
    • Bordeaux Combinatorics seminar (October 23, 2023)
    • Warwick Geometry and topology seminar (October 19, 2023)
  • The structure of quasi-transitive graphs:
    • Delft Discrete Mathematics and Optimization seminar (November 10, 2023)
    • UCL Cominatorics seminar (October 16, 2023)
    • Bordeaux Graph seminar (October 13, 2023)
  • Recoloring version of Hadwiger's conjecture:
    • Amsterdam combinatorics and probability seminar (October 31, 2023)
    • Eurocomb23
    • Oxford combinatorial theory seminar (February 1, 2022)
    • LSE combinatorics seminar (December 3, 2021)
    • JGA 2021 (November 18, 2021)
    • Bordeaux Graph seminar (October 15, 2021)
  • Strengthening a theorem of Meyniel:
    • JGA 2022 (November 2022)
    • Bordeaux Graph seminar (November 25, 2022)
    • Journées ANR GrR (June 2022)
  • Parametrized complexity of untangling knots:
    • LaBRI's Junior seminar (October 26, 2022)
    • ICALP 2022
  • Kempe changes in bounded treewidth graphs: Eurocomb 2021
  • Sparse Graph Coalition Workshop on Reconfiguration (May 2021)
  • Kempe changes on \(\Delta\)-colorings: Workshop on Combinatorial Reconfiguration at ICALP 2021
  • Journées ANR GrR (June 2021)


  • Networks (First year of IUT), 2024
  • Human computer interaction in C# (First year of IUT), 2024
  • Two lectures in the Master 2 Graph theory course: treewidth and graph minors, 2023
  • Algorithms on trees and functional programming (Second year of Bachelor degree), 2023
  • Combinatorics and probabilities (Second year of Bachelor degree), 2022
  • Introduction to computer science (First year of Bachelor degree), 2021
  • Colles en MP* et MPSI (weekly oral exams in mathematics) at Lycée du Parc, 2020


I practice bouldering several times a week and I recently started playing ultimate frisbee. I enjoy board sports of all kinds. When the whether is not good enough for those activities, I like to read sci-fi or fantasy, to cook or to play classical guitar.