Constraint satisfaction is a simple but powerful tool. Constraints identify the impossible and
reduce the realm of possibilities to effectively focus on the possible, allowing for a natural …

Many natural combinatorial problems can be expressed as constraint satisfaction problems.
This class of problems is known to be NP-complete in general, but certain restrictions on the …

The complexity and approximability of the constraint satisfaction problem (CSP) has been
actively studied over the past 20 years. A new version of the CSP, the promise CSP (PCSP) …

Polymorphisms, and How to Use Them Page 1 Polymorphisms, and How to Use Them Libor Barto
∗1, Andrei Krokhin2, and Ross Willard †3 1 Department of Algebra, Faculty of Mathematics and …

In a nutshell, a duality for a constraint satisfaction problem equates the existence of one
homomorphism to the non-existence of other homomorphisms. In this survey paper, we give …

A temporal constraint language is a set of relations that has a first-order definition in (Q;<),
the dense linear order of the rational numbers. We present a complete complexity …

An emerging area of research studies the complexity of constraint satisfaction problems
under restricted constraint languages. This article gives a self-contained, contemporary …

In a constraint satisfaction problem (CSP), the aim is to find an assignment of values to a
given set of variables, subject to specified constraints. The CSP is known to be NP-complete …

A Mal'tsev operation is a ternary operation φ that satisfies the identities φ(x,y,y)=φ(y,y,x)=x.
Constraint satisfaction problems involving constraints invariant under a Mal'tsev operation …

We propose a new algorithm for Promise Constraint Satisfaction Problems (PCSPs). It is a
combination of the Constraint Basic LP relaxation and the Affine IP relaxation (CLAP). We …