Packing paths of length at least two

We give a simple proof for Kaneko’s theorem which gives a su2cient and necessary condition for the existence of vertex disjoint paths in a graph, each of length at least two, that altogether cover all vertices of the original graph. Moreover we generalize this theorem and give a formula for the maximum number of vertices that can be covered by such a path system. c © 2004 Elsevier B.V. All rights reserved.