The Generalized Multiset Ordering is NP-Complete


Title: The Generalized Multiset Ordering is NP-Complete
Authors: René Thiemann (rene /dot/ thiemann /at/ uibk /dot/ ac /dot/ at) and Lukas Schmidinger
Submission date: 2022-04-20
Abstract: We consider the problem of comparing two multisets via the generalized multiset ordering. We show that the corresponding decision problem is NP-complete. To be more precise, we encode multiset-comparisons into propositional formulas or into conjunctive normal forms of quadratic size; we further prove that satisfiability of conjunctive normal forms can be encoded as multiset-comparison problems of linear size. As a corollary, we also show that the problem of deciding whether two terms are related by a recursive path order is NP-hard, provided the recursive path order is based on the generalized multiset ordering.
  author  = {René Thiemann and Lukas Schmidinger},
  title   = {The Generalized Multiset Ordering is NP-Complete},
  journal = {Archive of Formal Proofs},
  month   = apr,
  year    = 2022,
  note    = {\url{},
            Formal proof development},
  ISSN    = {2150-914x},
License: BSD License
Depends on: Weighted_Path_Order