Characterizing graph classes by intersections of neighborhoods
DOI:
https://doi.org/10.11575/cdm.v7i1.62138Abstract
The interplay between maxcliques (maximal cliques) and intersections of closed neighborhoods leads to new types of characterizations of several standard graph classes. For instance, being hereditary clique-Helly is equivalent to every nontrivial maxclique $Q$ containing the intersection of closed neighborhoods of two vertices of $Q$, and also to, in all induced subgraphs, every nontrivial maxclique containing a simplicial edge (an edge in a unique maxclique). Similarly, being trivially perfect is equivalent to every maxclique $Q$ containing the closed neighborhood of a vertex of $Q$, and also to, in all induced subgraphs, every maxclique containing a simplicial vertex. Maxcliques can be generalized to maximal cographs, yielding a new characterization of ptolemaic graphs.Downloads
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