Let G = (V, E) be an undirected graph with V = {1, . . . , K}. Let C1, . . . , CL be the set of maximal cliques in G. Let p(x) = (1/Z)*exp [Sum_l=1toL(ψ_l(x_Cl))]
Show that if A, B, C ⊂ V are disjoint, and if C separates A from B, (all paths from A to B go through C) then X_A, X_B are conditionally independent given X_C .