On the 4-color theorem for signed graphs
Combinatorics
2019-06-14 v1
Abstract
There are several ways to generalize graph coloring to signed graphs. M\'a\v{c}ajov\'a, Raspaud and \v{S}koviera introduced one of them and conjectured that in this setting, for signed planar graphs four colors are always enough, generalising thereby The Four Color Theorem. We disprove the conjecture.
Cite
@article{arxiv.1906.05638,
title = {On the 4-color theorem for signed graphs},
author = {František Kardoš and Jonathan Narboni},
journal= {arXiv preprint arXiv:1906.05638},
year = {2019}
}