Classes of term rewrite systems with polynomial confluence problems

The confluence property of ground (i.e., variable-free) term rewrite systems (GTRS) is well-known to be decidable. This was proved independently in [DTHL87,DHLT90] and in [Oya87] using tree automata techniques and ground tree transducer techniques (originated from this problem), yielding EXPTIME dec...

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Detalhes bibliográficos
Autores: Godoy Balil, Guillem, Nieuwenhuis, Robert Lukas Mario|||0000-0002-6489-2138
Formato: informe técnico
Fecha de publicación:2002
País:España
Recursos:Universitat Politècnica de Catalunya (UPC)
Repositorio:UPCommons. Portal del coneixement obert de la UPC
Idioma:inglés
OAI Identifier:oai:upcommons.upc.edu:2117/97487
Acesso em linha:https://hdl.handle.net/2117/97487
Access Level:acceso abierto
Palavra-chave:Confluence property of ground
GTRS
Term rewrite systems
Polynomial confluence
Àrees temàtiques de la UPC::Informàtica::Programació
Descrição
Resumo:The confluence property of ground (i.e., variable-free) term rewrite systems (GTRS) is well-known to be decidable. This was proved independently in [DTHL87,DHLT90] and in [Oya87] using tree automata techniques and ground tree transducer techniques (originated from this problem), yielding EXPTIME decision procedures (PSPACE for strings). Since then, it has been a well-known longstanding open question whether this bound is optimal (see, e.g., [RTA01]). In [CGN01] we gave the first polynomial-time algorithm for deciding the confluence of GTRS. Later in [Tiw02] this result was extended, using abstract congruent closure techniques, to linear-shallow TRS. Here, we give a new and much simpler proof of the latter result.