Regular homogeneously traceable nonhamiltonian graphs

Abstract

A graph is called homogeneously traceable if every vertex is an endpoint of a Hamilton path. In 1979 Chartrand, Gould and Kapoor proved that for every integer $n\ge 9,$ there exists a homogeneously traceable nonhamiltonian graph of order $n.$ The graphs they constructed are irregular. Thus it is natural to consider the existence problem of regular homogeneously traceable nonhamiltonian graphs. We prove two results: (1) For every even integer $n\ge 10,$ there exists a cubic homogeneously traceable nonhamiltonian graph of order $n;$ (2) for every integer $p\ge 18,$ there exists a $4$-regular homogeneously traceable graph of order $p$ and circumference $p-4.$ Unsolved problems are posed.