A Dichotomy Theorem for the Resolution Complexity of Random Constraint Satisfaction Problems

We consider random instances of constraint satisfaction problems where each variable has domain size O(1), each constraint is on O(1) variables and the constraints are chosen from a specified distribution. The number of constraints is cn where c is a constant. We prove that for every possible distribution, either the resolution complexity is almost surely polylogarithmic for sufficiently large c, or it is almost surely exponential for every c > 0. We characterize the distributions of each type. To do so, we introduce a closure operation on a set of constraints which yields the set of all constraints that, in some sense, appear implicitly in the random CSP.