English

Recolouring Homomorphisms to triangle-free reflexive graphs

Combinatorics 2024-03-06 v1

Abstract

For a graph HH, the HH-recolouring problem Recol(H)\operatorname{Recol}(H) asks, for two given homomorphisms from a given graph GG to HH, if one can get between them by a sequence of homomorphisms of GG to HH in which consecutive homomorphisms differ on only one vertex. We show that, if GG and HH are reflexive and HH is triangle-free, then this problem can be solved in polynomial time. This shows, at the same time, that the closely related HH-reconfiguration problem Recon(H)\operatorname{Recon}(H) of deciding whether two given homomorphisms from a given graph GG to HH are in the same component of the Hom-graph Hom(G,H)\operatorname{{Hom}}(G,H), can be solved in polynomial time for triangle-free reflexive graphs HH.

Keywords

Cite

@article{arxiv.2111.00723,
  title  = {Recolouring Homomorphisms to triangle-free reflexive graphs},
  author = {Jae-baek Lee and Jonathan A. Noel and Mark Siggers},
  journal= {arXiv preprint arXiv:2111.00723},
  year   = {2024}
}
R2 v1 2026-06-24T07:20:22.298Z