This class implements a non-local conditional constraint with the form of "R(A|B)", where "A" (a set), "B" (a set) are disjoint
with each other and both contains at least one variable from the Bayesian Belief Network.
This class implements a non-local marginal constraint with the form of "R(Y)", where "Y" (a set) contains
at least two variables from the Bayesian Belief Network.