GRAPHS WHOSE POWERS ARE CHORDAL AND GRAPHS WHOSE POWERS ARE INTERVAL-GRAPHS

The main theorem of this paper gives a forbidden induced subgraph cond ition on G that is sufficient for chordality of G(m). This theorem is a generalization of a theorem of Balakrishnan and Paulraja who had pro vided this only for m = 2. We also give a forbidden subgraph condition on G that is sufficient for chordality of G(2m). Similar conditions o n G that are sufficient for G(m) being an interval graph are also obta ined. In addition it is easy to see, that no family of forbidden (indu ced) subgraphs of G is necessary for G(m) being chordal or interval gr aph. (C) 1997 John Wiley & Sons, Inc.