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arXiv · 1911.10515

Intersection graph of maximal stars

Guilherme C. M. Gomes·Marina Groshaus·Carlos V. G. C. Lima·Vinicius F. dos Santos
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Abstract

A biclique of a graph $G$ is an induced complete bipartite subgraph of $G$ such that neither part is empty. A star is a biclique of $G$ such that one part has exactly one vertex. The star graph of $G$ is the intersection graph of the maximal stars of $G$. A graph $H$ is star-critical if its star graph is different from the star graph of any of its proper induced subgraphs. We begin by presenting a bound on the size of star-critical pre-images by a quadratic function on the number of vertices of the star graph, then proceed to describe a Krausz-type characterization for this graph class; we combine these results to show membership of the recognition problem in \textsf{NP}. We also present some properties of star graphs. In particular, we show that they are biconnected, that every edge belongs to at least one triangle, characterize the structures the pre-image must have in order to generate degree two vertices, and bound the diameter of the star graph with respect to the diameter of its pre-image. Finally, we prove a monotonicity theorem, which we apply to list every star graph on at most eight vertices.

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Guilherme C. M. Gomes, Marina Groshaus, Carlos V. G. C. Lima, Vinicius F. dos Santos. 2019-11-24. Intersection graph of maximal stars. https://arxiv.org/abs/1911.10515

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