منابع مشابه
Marked PCP is decidable
We show that the marked version of the Post Correspondence Problem, where the words on a list are required to diier in the rst letter, is decidable. On the other hand, we prove that PCP remains undecidable if we only require the words to diier in the rst two letters. Thus we locate the decidability/undecidability-boundary between marked and 2-marked PCP.
متن کاملDecidability and Undecidability of Marked PCP
We show that the marked version of the Post Correspondence Problem, where the words on a list are required to di er in the rst letter, is decidable. On the other hand, if we only require the words to di er in the rst two letters, the problem remains undecidable. Thus we sharply locate the decidability/undecidability-boundary between marked and 2-marked PCP.
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Description Logics [1] are logical formalisms for representing information about classes and objects. They are very often used as the basis of knowledge representation systems and have been used recently to develop OWL semantic web language, which can be viewed as an expressive Description Logic. There is an impressive variety of Description Logics with diverse expressiveness and complexity, or...
متن کاملUnary PCF is Decidable
We show that unary PCF, a very small fragment of Plotkin’s PCF [?], has a decidable observational pre-order, and that its fully abstract model is effectively presentable. This is in marked contrast to larger fragments, where corresponding results fail [?]. The techniques used are adaptions of those of Padovani [?], who applied them to the minimal model of the simply typed lambda calculus.
متن کاملTicket Entailment is decidable
We prove the decidability of the logic T→ of Ticket Entailment. Raised by Anderson and Belnap within the framework of relevance logic, this question is equivalent to the question of the decidability of type inhabitation in simply-typed combinatory logic with the partial basis BBIW. We solve the equivalent problem of type inhabitation for the restriction of simply-typed lambda-calculus to heredi...
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2001
ISSN: 0304-3975
DOI: 10.1016/s0304-3975(99)00163-2