Davoodi, Akbar and Omoomi, Behnaz - On the 1-2-3-conjecture

dmtcs:2117 - Discrete Mathematics & Theoretical Computer Science, February 10, 2015, Vol. 17 no. 1 (in progress)
On the 1-2-3-conjecture

Authors: Davoodi, Akbar and Omoomi, Behnaz

A k-edge-weighting of a graph G is a function w:E(G)→{1,…,k}. An edge-weighting naturally induces a vertex coloring c, where for every vertex v∈V(G), c(v)=∑e∼vw(e). If the induced coloring c is a proper vertex coloring, then w is called a vertex-coloring k-edge-weighting (VC k-EW). Karoński et al. (J. Combin. Theory Ser. B, 91 (2004) 151 13;157) conjectured that every graph admits a VC 3-EW. This conjecture is known as the 1-2-3-conjecture. In this paper, first, we study the vertex-coloring edge-weighting of the Cartesian product of graphs. We prove that if the 1-2-3-conjecture holds for two graphs G and H, then it also holds for G□H. Also we prove that the Cartesian product of connected bipartite graphs admits a VC 2-EW. Moreover, we present several sufficient conditions for a graph to admit a VC 2-EW. Finally, we explore some bipartite graphs which do not admit a VC 2-EW.

Source : oai:HAL:hal-01196861v1
Volume: Vol. 17 no. 1 (in progress)
Section: Graph Theory
Published on: February 10, 2015
Submitted on: August 22, 2012
Keywords: Vertex-coloring edge-weighting,1-2-3-conjecture,Edge weighting,Vertex-coloring 2-edge-weighting,[INFO.INFO-DM] Computer Science [cs]/Discrete Mathematics [cs.DM],[INFO.INFO-HC] Computer Science [cs]/Human-Computer Interaction [cs.HC]