Expressiveness of Semipositive Logic Programs with Value Invention
نویسنده
چکیده
We study the expressive power of the relational query language wILOG 1 2 ;: of semipositive datalog programs extended with a mechanism of safe value invention. We adopt a semantics for value invention based on the use of Skolem functor terms. We show that this language expresses exactly the class of semimonotone queries, that is, the class of computable queries that are preserved under extensions.
منابع مشابه
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The expressive power of the family wILOG(:) of relational query languages is investigated. The languages are rule based, with value invention and strati ed negation. The semantics for value invention is based on Skolem functor terms. We study a hierarchy of languages based on the number of strata allowed in programs. We rst show that, in presence of value invention, the class of strati ed progr...
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تاریخ انتشار 1996