Distance constraint satisfaction problems

We study the complexity of constraint satisfaction problems for templates Γ over the integers where the relations are first-order definable from the successor function. In the case that Γ is locally finite (i. e. , the Gaifman graph of Γ has finite degree), we show that Γ is homomorphically equivalent to a structure with one of two classes of polymorphisms (which we call modular max and modular min) and the CSP for Γ can be solved in polynomial time, or Γ is homomorphically equivalent to a finite transitive structure, or the CSP for Γ is NP-complete. Assuming a widely believed conjecture from finite domain constraint satisfaction (we require the tractability conjecture by Bulatov, Jeavons and Krokhin in the special case of transitive finite templates), this proves that those CSPs have a complexity dichotomy, that is, are either in P or NP-complete.

Authors

• Manuel Bodirsky
• Victor Dalmau
• Barnaby Martin
• Antoine Mottet
• Michael Pinsker

Keywords

• Constraint satisfaction problems
• Complexity dichotomy
• Integers with successor
• Reducts
• Primitive positive definability
• Endomorphisms