A Characterization of Substar Graphs

The intersection graphs of stars in some tree are known as substar graphs. In this paper we give a characterization of substar graphs by the list of minimal forbidden induced subgraphs. This corrects a flaw in the main result of Chang, Jacobson, Monma and West (Subtree and substar intersection numbers, Discrete Appl. Math. 44, 205-220 (1993)) and this leads to a different list of minimal forbidden induced subgraphs.