http://en.wikipedia.org/wiki/Markov_random_field MRF Markov network Markov random field a set of random variables having a Markov property described by an undirected graph. A Markov random field may be considered to be a generalization of a Markov chain in multiple dimensions. In a Markov chain, state depends only on the previous state in time, whereas in a Markov random field, each state depends on its neighbors in any of multiple directions. A Markov random field may be visualized as a field or graph of random variables, where the distribution of each random variable depends on the neighboring variables with which it is connected. undirected graphical model