Finitely Related Algebras In Congruence Distributive Varieties Have Near Unanimity Terms

Source abstract

Abstract we show that every finite, finitely related algebra in a congruence distributive variety has a near unanimity term operation. as a consequence we solve the near unanimity problem for relational structures: it is decidable whether a given finite set of relations on a finite set admits a compatible near unanimity operation. this consequence also implies that it is decidable whether a given finite constraint language defines a constraint satisfaction problem of bounded strict width.