On Incidence Coloring of Complete Multipartite and Semicubic Bipartite Graphs
Discussiones Mathematicae. Graph Theory, Tome 38 (2018) no. 1, pp. 107-119

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In the paper, we show that the incidence chromatic number χ_i of a complete k-partite graph is at most Δ + 2 (i.e., proving the incidence coloring conjecture for these graphs) and it is equal to Δ + 1 if and only if the smallest part has only one vertex (i.e., Δ = n − 1). Formally, for a complete k-partite graph G = K_r_1,r_2,...,r_k with the size of the smallest part equal to r_1 ≥ 1 we have χ_i (G)= Δ(G)+1 amp; if  r_1=1, Δ(G)+2 amp; if  r_1 gt;1. In the paper we prove that the incidence 4-coloring problem for semicubic bipartite graphs is 𝒩𝒫-complete, thus we prove also the 𝒩𝒫-completeness of L(1, 1)-labeling problem for semicubic bipartite graphs. Moreover, we observe that the incidence 4-coloring problem is 𝒩𝒫-complete for cubic graphs, which was proved in the paper [12] (in terms of generalized dominating sets).
Keywords: incidence coloring, complete multipartite graphs, semicubic graphs, subcubic graphs, -completeness, L (1,1)-labelling
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Janczewski, Robert; Małafiejski, Michał; Małafiejska, Anna. On Incidence Coloring of Complete Multipartite and Semicubic Bipartite Graphs. Discussiones Mathematicae. Graph Theory, Tome 38 (2018) no. 1, pp. 107-119. http://geodesic.mathdoc.fr/item/DMGT_2018_38_1_a8/