On rewrite constraints and context unification

On rewrite constraints and context unification

We show that stratified context unification, which is one of the most expressive fragments of context unification known to be decidable, is equivalent to the satisfiability problem of slightly generalized rewriting constraints.

On Rewrite Constraints

Dominance constraints in stratified context unification

We express dominance constraints in the once-only nesting fragment of stratified context unification, which therefore is NP-complete.

Linear Second-Order Unification and Context Unification with Tree-Regular Constraints

Linear Second-Order Unification and Context Unification are closely related problems. However, their equivalence was never formally proved. Context unification is a restriction of linear second-order unification. Here we prove that linear second-order unification can be reduced to context unification with tree-regular constraints. Decidability of context unification is still an open question. W...

On Equality Up-to Constraints over Finite Trees, Context Unification, and One-Step Rewriting

We introduce equality up-to constraints over nite trees and investigate their expressiveness. Equality up-to constraints subsume equality constraints, subtree constraints, and one-step rewriting constraints. We establish a close correspondence between equality up-to constraints over nite trees and context uniication. Context uniication subsumes string uniication and is subsumed by linear second...