On the Complexity of Rainbow Vertex Colouring Diametral Path Graphs

Jakob Dyrseth, Paloma Thomé de Lima

Research output: Conference Article in Proceeding or Book/Report chapterArticle in proceedingsResearchpeer-review


Given a graph and a colouring of its vertices, a rainbow vertex path is a path between two vertices such that all the internal nodes of the path are coloured distinctly. A graph is rainbow vertex-connected if between every pair of vertices in the graph there exists a rainbow vertex path. We study the problem of deciding whether a given graph can be coloured using k or less colours such that it is rainbow vertex-connected. Note that every graph G needs at least diam(G)-1 colours to be rainbow vertex connected.
Heggernes et al. [MFCS, 2018] conjectured that if G is a graph in which every induced subgraph has a dominating diametral path, then G can always be rainbow vertex coloured with diam(G)-1 many colours. In this work, we confirm their conjecture for chordal, bipartite and claw-free diametral path graphs. We complement these results by showing the conjecture does not hold if the condition on every induced subgraph is dropped. In fact we show that, in this case, even though diam(G) many colours are always enough, it is NP-complete to determine whether a graph with a dominating diametral path of length three can be rainbow vertex coloured with two colours.
Original languageEnglish
Title of host publication33rd International Symposium on Algorithms and Computation (ISAAC 2022)
PublisherDagstuhl Publishing, Germany
Publication date2022
Publication statusPublished - 2022


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