A parity walk in an edge-coloring of a graph is a walk along which each color is used an even number of times. A parity edge-coloring (respectively, strong parity edge-coloring) is an edge-coloring in which there is no nontrivial parity path (respectively, open parity walk). The parity edge-chromatic number p(G) (respectively, strong parity edge-chromatic number pˆ(G) ) is the least number of colors in a parity edge-coloring (respectively, strong parity edge-coloring) of G. Notice that pˆ(G)≥p(G)≥χ′(G)≥Δ(G) for any graph G. In this paper, we determine pˆ(G) and p(G) for some complete bipartite graphs and some products of graphs. For instance, we determine pˆ(Km,n) and p(K m,n ) for m≤n with n≡0,−1,−2 (mod 2⌈lg m⌉).
Journal of Combinatorial Optimization 24(4), p.427-436