Discrete Mathematics ( IF 0.770 ) Pub Date : 2020-02-01 , DOI: 10.1016/j.disc.2020.111833 Wei Wang; Jianguo Qian
Let be a signed graph where two edges joining the same pair of vertices with opposite signs are allowed. The zero-free chromatic number of is the minimum even integer such that admits a proper coloring . The zero-free list chromatic number is the list version of zero-free chromatic number. is called zero-free chromatic-choosable if . We show that if has at most vertices then is zero-free chromatic-choosable. This result strengthens Noel–Reed–Wu Theorem which states that every graph with at most vertices is chromatic-choosable, where is the chromatic number of .