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Rainbow connection numbers of line graphs, middle graphs and total graphs

Yuefang Sun


A path in an edge-colored graph, where adjacent edges may be colored the same,is a rainbow path if no two edges of it are colored the same. A nontrivial connected graph G is rainbow connected if there is a rainbow path connecting any two vertices, and the rainbow connection number of G, denoted rc(G), is the minimum number of colors that are needed in order to make G rainbow connected. In this paper, we investigate the rainbow connection numbers of the line graph, middle graph and total graph of a connected triangle-free graph G. We obtain three (near) sharp upper bounds in terms of the number of vertex-disjoint cycles of the original graph G.


rainbow connection number, line graph, middle graph, total graph

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