Main focus of my research currently is extension of coloring and homomorphism results from graphs to signed graphs. This is of special importance because it provides a better connection with minor theory. It is also a main theme of an ANR project named HOSIGRA (HOmomorphisms of SIgned GRAPhs). There are plenty of questions with different level of difficulties, suitable for M1, M2 and Ph.D. projects. For some details you can see the website of the project by clicking on ANR-HOSIGRA 2018-2022 on the right column. Or you can simply write me an e-mail for an appointment and discussion.

My current and previous students:

Ph. D (current):

  1. Weiqiang Yu Started October 2019. Supported by Chinese Science Council.
    Project: Packing number of signed graphs
  2. Yiting Jiang cotutelle. Started September 2018.
  3. Mouhamad El Joubbeh cotutelle with Lebanese University, started September 2018.
    Project: Coloring and orientation.
  4. Rongxing Xu, Visiting Ph. D. student October 2018-October 2020.
    Project: List coloring and homomorphisms of signed graphs.
  5. Zhouningxin Wang, Started October 2018. Supported by Cofund-FSMP, started October 2018.
    Project: Circular coloring and Homomorphisms of signed graphs.

Ph. D (graduated)

  1. Suchismita Mishra Visiting Ph. D. student June 2019-December 2019.
    Project: Strong edge-coloring and exact squares of graphs
  2. Maria Abi Aad Lebanese University, 2015-2017.
    Project: Hamiltonicity and coloring of digraphs.
  3. Qiang Sun, University Paris 11, 2012-2016.
    Project: mapping (planar graphs) into projective cubes.


  1. Laila El Koussy, 2020-2021, Logique mathématique et fondements de l'informatique à l’Université de Paris. Bourse: Rafea Tahtawi de Campus France.
    Project: Triple transitive graphs.
  2. Julio Maldonado Henríquez, 2020-2021, MPRI, with FSMP-scholarship.
    Project: (H, Π )-critical graphs.
  3. Priyanka Aravindan, 2019-2020 Coimbatore, India and 2020-2021 MPRI , with FSMP-scholarship.
    Project: C4-cricial graphs of high girth.
  4. Samuel Nalin, 2018-2019 M1 Paris-Diderot,
    Project: Grötzsch theorem and signed graphs
  5. Zhouningxin Wang, 2017-2018 Erasmus Paris 6, supported by FSMP,
    Project: Signed subdivisions of K4.
  6. Sheng-Ju Cho, 2013-2014 Paris-Sud.
    Project: The Problem of Minimum Signature of Signed Complete Graphs.
  7. Sagnik Sen, ALGANT program, 2009-2010 LaBRI-Bordeaux, joint supervision with Eric Sopena.
    Project: Oriented chromatic number of planar graphs.


  1. Ananta Mukherjee, summer 2019,
    Project: list coloring of planar graphs"
  2. Maria Abi Aad, spring 2014,
    Project: Decomposing directed graphs.
  3. Hajar Habjaouim, summer 2013,
    Project: Zaslavsky chromatic number of signed planar graphs.
  4. Laurent Nieuviarts, summer 2013,
    Project: Eigenvalues of signed graphs