The Structure of Bull-Free Perfect Graphs


  • Contract grant sponsor: NSF; Contract grant numbers: DMS-0758364; DMS-1001091 (to M. C.).


The bull is a graph consisting of a triangle and two vertex-disjoint pendant edges. A graph is called bull-free if no induced subgraph of it is a bull. A graph G is perfect if for every induced subgraph H of G, the chromatic number of H equals the size of the largest complete subgraph of H. This article describes the structure of all bull-free perfect graphs.