Abstract not found

. This paper presents a partial deduction method for disjunctive logic programs. We first show that standard partial deduction in logic programming is not applicable as it is in the context of disjunctive logic programs. Then we introduce a new partial deduction technique for disjunctive logic programs, and show that it preserves the minimal model semantics of positive disjunctive programs, and the stable model semantics of normal disjunctive programs. Goal-oriented partial deduction is also presented for query optimization. 1 Introduction Partial deduction or partial evaluation is known as one of the optimization techniques in logic programming. Given a logic program, partial deduction derives a more specific program through performing deduction on a part of the program, while preserving the meaning of the original program. Such a specialized program is usually more efficient than the original program when executed. Partial deduction in logic programming was firstly introduced by Kom...

An Unfold/Fold transformation system is a source-to-source rewriting methodology devised to improve the efficiency of a program. Any such transformation should preserve the main properties of the initial program: among them, termination. To this end, in the field of logic programming, the class of acyclic programs plays an important role, as it is closely related to the one of terminating programs. The two classes coincide when negation is not allowed in the bodies of the clauses. In this paper it is proven that the Unfold/Fold transformation system defined by Tamaki and Sato preserves the acyclicity of the initial program. As corollaries, it follows that when the transformation is applied to an acyclic program, then finite failure set for definite programs is preserved; in the case of normal programs, all major declarative and operational semantics are preserved as well. These results cannot be extended to the class of left terminating programs without modifying the definitio...

The well-founded semantics and stable model semantics have proven popular semantics for logic programs. However, these semantics (and others) are not directly amenable to logical reasoning since logically equivalent logic programs may have different stable or well-founded models. Many natural simplifications are not universally valid. Furthermore, in some semantics -- including the stable model semantics -- the definition of a new predicate in terms of old predicates can affect the semantics of the old predicates. We provide valid transformation systems for the well-founded, stable model and Clark-completion semantics. We give restrictions on the application of the simplifications which make them valid, and restrictions on the form of new definitions which avoid unwelcome side-effects on other predicates. The resulting transformation systems form a basis for reasoning in these unstable semantics.

Partial deduction is known as an optimization technique in logic programming. In the context of abductive logic programming, however, we present in this paper that normal partial deduction does not preserve explanations for abductive reasoning. Then we provide an alternative method of partial deduction, called abductive partial deduction, which is shown to preserve the meanings of abductive logic programs. A method of partial abduction is also introduced as an optimization for abductive reasoning in logic programs. 1 Introduction Partial deduction [Kom92] is an optimization technique in logic programming, which performs deduction on a part of a program while retaining the meaning of the original program. Partial deduction is used in various extensions of logic programming, and is known to preserve the semantics of normal logic programs [TS84, LS91, Seki91, Seki93] and disjunctive logic programs [SS94, BD94]. Abductive logic programming [KKT92] is one of the extensions of logic progra...

this paper our aim is to adapt and apply methods of giving semantics to non-monotonic rule systems to the purpose of making new definitions in an unestablished area. Inasmuch as we maximize predicate extensions and have different motivations from non-monotonic reasoning, this work can serve as a guiding example in the development of more abstract notions of non-monotonic rule systems, as begun in [19].