TY - GEN
T1 - Unification modulo ACUI plus homomorphisms/distributivity
AU - Anantharaman, Siva
AU - Narendran, Paliath
AU - Rusinowitch, Michael
N1 - Publisher Copyright: © Springer-Verlag Berlin Heidelberg 2003.
PY - 2003
Y1 - 2003
N2 - In this paper, we consider the unification problem over theories that are extensions of ACI or ACUI, obtained by adding finitely many homomorphism symbols, or a symbol ‘∗’ that distributes over the ACUI-symbol denoted ‘+’. We first show that when we adjoin a set of commuting homomorphisms to ACUI, unification is undecidable. We then consider the ACUIDl-unification problem, i.e., unification modulo ACUI plus left-distributivity of a given ‘∗’ w.r.t. ‘+’, and prove its NEXPTIME-decidability. When we assume the symbol ‘∗’ to be 2-sided distributive w.r.t. ‘+’, we get the theory ACUID, for which the unification problem remains decidable. But when equations of associativitycommutativity, or just of associativity, on ‘∗’ are added on to ACUID, the unification problem becomes undecidable.
AB - In this paper, we consider the unification problem over theories that are extensions of ACI or ACUI, obtained by adding finitely many homomorphism symbols, or a symbol ‘∗’ that distributes over the ACUI-symbol denoted ‘+’. We first show that when we adjoin a set of commuting homomorphisms to ACUI, unification is undecidable. We then consider the ACUIDl-unification problem, i.e., unification modulo ACUI plus left-distributivity of a given ‘∗’ w.r.t. ‘+’, and prove its NEXPTIME-decidability. When we assume the symbol ‘∗’ to be 2-sided distributive w.r.t. ‘+’, we get the theory ACUID, for which the unification problem remains decidable. But when equations of associativitycommutativity, or just of associativity, on ‘∗’ are added on to ACUID, the unification problem becomes undecidable.
KW - Complexity
KW - E-Unification
KW - Minsky machine
KW - Post correspondence problem
KW - Rewrite reachability
KW - Set constraints
UR - https://www.scopus.com/pages/publications/7044229280
U2 - 10.1007/978-3-540-45085-6_38
DO - 10.1007/978-3-540-45085-6_38
M3 - Conference contribution
SN - 3540405593
SN - 9783540405597
T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
SP - 442
EP - 457
BT - Automated Deduction - CADE-19 - 19th International Conference on Automated Deduction, Proceedings
A2 - Baader, Franz
PB - Springer Verlag
T2 - 19th International Conference on Automated Deduction, CADE 2003
Y2 - 28 July 2003 through 2 August 2003
ER -