Michio Oyamaguchi

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In 1979 Huet and Levy introduced the class of sequential term-rewriting systems in which callby-need computations are possible (without look-ahead) and defined the subclass called strongly sequential systems for which needed redexes in a given term are effectively found [chapter in Computational Logic: Essays in Honor ofAlan Robinson, J.-L. Lassez and G.(More)
G.Huet (1980) showed that a left-linear term-rewriting system (TRS) is Church-Rosser (CR) if P ! j Q for every critical pair < P;Q > where P ! j Q is a parallel reduction from P to Q. But, it remains open whether it is CR when Q ! j P for every critical pair < P;Q >. In this paper, we give a partial solution to this problem, that is, a left-linear TRS is CR(More)
The unification problem for term rewriting systems (TRSs) is the problem of deciding, for a given TRS R and two terms M and N , whether there exists a substitution h such that Mh and Nh are congruent modulo R (i.e., Mh$ R Nh). In this paper, the unification problem for confluent right-ground TRSs is shown to be decidable. To show this, the notion of minimal(More)
The equivalence problem for deterministic real-time pushdown automata is shown to be decidable. This result is obtained by showing that Valiant's parallel stacking technique using a replacement function introduced in this paper succeeds for deterministic real-time pushdown automata. Equivalence is also decidable for two deterministic pushdown automata, one(More)