2014/11/06 by Kaiser, Tomáš, Rollová, Edita
#05C21 #Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.1411.1788
Bouchet conjectured in 1983 that each signed graph that admits a nowhere-zero flow has a nowhere-zero 6-flow. We prove that the conjecture is true for all signed series-parallel graphs. Unlike the unsigned case, the restriction to series-parallel graphs is nontrivial; in fact, the result is tight for infinitely many graphs.