Dagstuhl Seminar Proceedings. 06401 - Complexity of Constraints
Doi
Abstract
The Galois correspondence involving polymorphisms and co-clones
has received a lot of attention in regard to constraint satisfaction problems.
However, it fails if we are interested in a reduction giving equivalence
instead of only satisfiability-equivalence. We show how a similar
Galois connection involving weaker closure operators can be applied for
these problems. As an example of the usefulness of our construction, we
show how to obtain very short proofs of complexity classifications in this
context