Distributive Lattice Polymorphism on Reflexive Graphs

Abstract

In this paper we give two characterisations of the class of reflexive graphs admitting distributive lattice polymorphisms and use these characterisations to address the problem of recognition: for a reflexive graph G in which no two vertices have the same neighbourhood, we find a polynomial time algorithm to decide if G admits a distributive lattice polymorphism.

arXiv comment20 pages, 6 figures