RESUMEN

An edge in a graph G is called a wing if it is one of the two nonincident edges of an induced P4 (a path on four vertices) in G. For a graph G, its wing-graph W (G) is defined as the graph whose vertices are the wings of G, and two vertices in W (G) are connected if the corresponding wings in G belong to the same P4. We will characterize all graphs whose wing-graph is a cycle. This solves a conjecture posed by Hoang [9]. © 1999 John Wiley & Sons, Inc. J Graph Theory 31:51-66, 1999