Unification in datastructure multisets
Journal of Automated Reasoning
On equational theories, unification and decidability
on Rewriting techniques and applications
Journal of Automated Reasoning
An algebraic approach to unification under associativity and commutativity
Journal of Symbolic Computation
Journal of Symbolic Computation
A Machine-Oriented Logic Based on the Resolution Principle
Journal of the ACM (JACM)
A Unification Algorithm for Associative-Commutative Functions
Journal of the ACM (JACM)
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
Canonical Forms and Unification
Proceedings of the 5th Conference on Automated Deduction
Journal of Automated Reasoning
Permutative rewriting and unification
Information and Computation
Unification and Matching Modulo Leaf-Permutative Equational Presentations
IJCAR '08 Proceedings of the 4th international joint conference on Automated Reasoning
Determining unify-stable presentations
RTA'07 Proceedings of the 18th international conference on Term rewriting and applications
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An equational theory @? is permutative if for all terms s, t: s = "@?t implies that the terms s and t contain the same symbols with the same number of occurrences. The class of permutative equational theories includes the theory of AC (associativity and commutativity). It is shown in this research note that there is no algorithm that decides @?-unifiability of terms for all permutative theories. The proof technique is to provide, for every Turing machine M, a permutative theory with a confluent term-rewriting system such that narrowing on certain terms simulates the Turing machine M.