Carlos Viegas Damásio

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The evolution of logic programming semantics has included the introduction of a new explicit form of negation, beside the older implicit (or default) negation typical of logic programming. The richer language has been shown adequate for a spate of knowledge representation and reasoning forms. The widespread use of such extended programs requires the(More)
In this paper we show the embedding of Hybrid Probabilis-tic Logic Programs into the rather general framework of Residuated Logic Programs, where the main results of (deenite) logic programming are validly extrapolated, namely the extension of the immediate consequences operator of van Emden and Kowalski. The importance of this result is that for the rst(More)
A general framework of logic programming allowing for the combination of several adjoint lattices of truth-values is presented. The main contribution is a new sufficient condition which guarantees termination of all queries for the fixpoint semantics for an interesting class of programs. Several extensions of these conditions are presented and related to(More)
In this paper we de ne a sound and complete top{down semantic tree characterization, that includes pruning rules, of the well{founded semantics for programs extended with explicit negation (WFSX), and compare it to other related approaches. It is amenable to a simple implementation (in appendix), and by its nature readily allows pre{processing into Prolog,(More)
In this paper we describe REVISE, an extended logic programming system for revising knowledge bases. REVISE is based on logic programming with explicit negation, plus a two-valued assumption revision to face contradiction , encompasses the notion of preference levels. Its reliance on logic programming allows efficient computation and declarativity, whilst(More)
A general logic programming framework allowing for the combination of several adjoint lattices of truth-values is presented. The language is sorted, enabling the combination of several reasoning forms in the same knowledge base. The contribution of the paper is two-fold: on the one hand, sufficient conditions guaranteeing termination of all queries for the(More)