CSP duality and trees of bounded pathwidth

We study non-uniform constraint satisfaction problems definable in monadic Datalog stratified by the use of non-linearity. We show how such problems can be described in terms of homomorphism dualities involving trees of bounded pathwidth and in algebraic terms. For this, we introduce a new parameter for trees that closely approximates pathwidth and can be characterised via a hypergraph searching game. Key words: constraint satisfaction problem, homomorphism duality, Datalog, polymorphisms, bounded pathwidth

• Type: Journal
• Year: 2010
• Where: TCS
• Authors: Catarina Carvalho, Víctor Dalmau, Andrei A. Krokhin
• Keywords: Hypergraph Searching Game, Non-uniform Constraint Satisfaction, Satisfaction Problem, TCS 2010, Theoretical Computer Science