Handbook of theoretical computer science (vol. B)
Simple second-order languages for which unification is undecidable
Theoretical Computer Science
Bottom-up tree pushdown automata: classification and connection with rewrite systems
Theoretical Computer Science
Haskell overloading is DEXPTIME-complete
Information Processing Letters
Term rewriting and all that
On the undecidability of second-order unification
Information and Computation - Special issue on RTA-98
Monadic Simultaneous Rigid E-Unification and Related Problems
ICALP '97 Proceedings of the 24th International Colloquium on Automata, Languages and Programming
Proofs and Reachablity Problem for Ground Rewrite Systems
Proceedings of the 6th International Meeting of Young Computer Scientists on Aspects and Prospects of Theoretical Computer Science
Decidable and Undecidable Second-Order Unification Problems
RTA '98 Proceedings of the 9th International Conference on Rewriting Techniques and Applications
The Decidability of Simultaneous Rigid E-Unification with One Variable
RTA '98 Proceedings of the 9th International Conference on Rewriting Techniques and Applications
Term Rewriting, French Spring School of Theoretical Computer Science, Advanced Course
The Relation Between Second-Order Unification and Simultaneous Rigid E-Unification
LICS '98 Proceedings of the 13th Annual IEEE Symposium on Logic in Computer Science
Complexity of finitely presented algebras
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Tree acceptors and some of their applications
Journal of Computer and System Sciences
Decidable Fragments of Simultaneous Rigid Reachability
ICAL '99 Proceedings of the 26th International Colloquium on Automata, Languages and Programming
Solvability of Context Equations with Two Context Variables is Decidable
CADE-16 Proceedings of the 16th International Conference on Automated Deduction: Automated Deduction
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We show that rigid reachability, the non-symmetric form of rigid E-unification, is undecidable already in the case of a single constraint. From this we infer the undecidability of a new rather restricted kind of second-order unification. We also show that certain decidable subclasses of the problem which are ρ-complete in the equational case become EXPTIME-complete when symmetry is absent. By applying automata-theoretic methods, simultaneous monadic rigid reachability with ground rules is shown to be in EXPTIME.