On the Computational Complexity of Monotone Constraint Satisfaction Problems

Constraint Satisfaction Problems (CSP) constitute a convenient way to capture many combinatorial problems. The general CSP is known to be NPcomplete, but its complexity depends on a parameter, usually a set of relations, upon which they are constructed. Following the parameter, there exist tractable and intractable instances of CSPs. In this paper we show a dichotomy theorem for every finite domain of CSP including also disjunctions. This dichotomy condition is based on a simple condition, allowing us to classify monotone CSPs as tractable or NP-complete. We also prove that the meta-problem, verifying the tractability condition for monotone constraint satisfaction problems, is fixed-parameter tractable. Moreover, we present a polynomial-time algorithm to answer this question for monotone CSPs over ternary domains.