Weimin, Li, Inverses and Pseudo-Inverses of a Strong Endomorphism of a Graph, Acta Mathematica Sinica, New Series Chinese Journal of Mathematics, 11(4), 1995, pp. 372-380
In this paper, we explicitly describe all the inverses and pseudo-inverses of a strong endomorphism of a graph. The number of them is determined. In addition, we give a characterization of a strong endomorphism whose pseudo-inverse set coincides with its inverse set. The graph, each strong endomorphism of which has this property, is also investigated.