This was a project to develop signed graph homomorphisms.

The main meeting was held October 1-7, 2012, at la Gabertie, Thezac.

Co-organizers: Laurent Beadou, Alexandre Pinlou and Eric Sopena.


Yandong Bai, Larent Beaudou, Richard Brewster, Clement Charpentier, Florent Foucaud, Ararat Harutyunyan, Weihua He, Hao Li, Reza Naserasr, Pascal Ochem, Alexandre Pinlou, Andre Raspaud, Sagnik Sen, Eric Sopena, Petru Valicov, Valentin Borozan,


First day I presented the new concept of signed graph homomorphisms, and some possible direction to go from there.

Each morning, after the breakfast, we had a meeting to discuss the new ideas from the previous day. Then we split into small groups to work on our favorite subject.

A lecture on the subject of nowhere-zero flow on signed graph was given by Andre Raspaud.

Title of research problems considered:

  1. Signed chromatic number of signed planar graphs
  2. Analogue of Zeager-Zhang conjecture for signed bipartite graphs
  3. Complexity of (G, \Sigma)-coloring
  4. Categorical product for signed graphs
  5. Extensions of Hadwiger's conjecture
  6. Nowhere-zero flows on signed graphs

As of December 2013 at least two papers based on results from this meeting are being written.