Random Binary CSP with uniform distribution.

A random CSP is defined by a four-tuple (n, d, p1, p2), where n denotes the number of variables and d denotes the domain size of each variable, p1 and p2 are two probabilities. They are used to generate randomly the binary constraints among the variables. p1 represents the probability that a constraint exists between two different variables and p2 represents the probability that a pair of values in the domains of two variables connected by a constraint are incompatible.

We use a so called model B of Random CSP (n, d, n1, n2) where n1 = p1*n*(n-1)/2 pairs of variables are randomly and uniformly selected and binary constraints are posted between them. For each constraint, n2 = p1*d^2 randomly and uniformly selected pairs of values are picked as incompatible.