Generalisation of the Hammersley-Clifford Theorem on Bipartite Graphs

Abstract

The Hammersley-Clifford theorem states that if the support of a Markov random field has a safe symbol then it is a Gibbs state with some nearest neighbour interaction. In this paper we generalise the theorem with an added condition that the underlying graph is bipartite. Taking inspiration from "Gibbs Measures and Dismantlable Graphs" by Brightwell and Winkler we introduce a notion of folding for configuration spaces called strong config-folding proving that if all Markov random fields supported on $X$ are Gibbs with some nearest neighbour interaction so are Markov random fields supported on the 'strong config-folds' and 'strong config-unfolds' of $X$.Comment: 27 pages, 7 figures; Typos corrected and some notation has been change