Exponential families of minimally non-coordinated graphs

FRANCISCO SOULIGNAC; GABRIEL SUEIRO

REVISTA DE LA UNIóN MATEMáTICA ARGENTINA

UNION MATEMATICA ARGENTINA

Año: 2009 vol. 50 p. 75 - 85

0041-6932

A graph G is coordinated if, for every induced subgraph H of G, the minimum number of colors that can be assigned to the cliques of Hin such a way that no two cliques with non-empty intersection receive the same color is equal to the maximum number of cliques of H with a common vertex. In a previous work, coordinated graphs were characterized by minimal forbidden induced subgraphs within some classes of graphs. In this note, we present families of minimally non-coordinated graphs whose cardinality grows exponentially on the number of vertices and edges. Furthermore, we describe some ideas to generate similar families. Based on these results, it seems difficult to find a general characterization of coordinated graphs by minimal forbidden induced subgraphs.