We extend static filtering in [8], a query optimization strategy based on seminaive evaluation on system graphs, so that it can efficiently handle stratified programs without extra overhead. The computation of static ...
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We extend static filtering in [8], a query optimization strategy based on seminaive evaluation on system graphs, so that it can efficiently handle stratified programs without extra overhead. The computation of static filters is formalized as a transformation so that the least fixed point of the transformation can be the static filters. The static filtering on stratified programs is shown to be complete with respect to the iterated fixed point semantics.
Negation is useful in the majority of the real world applications. However, its introduction leads to semantic and canonical problems. We propose in this paper an approach based on stratification to deal with negation...
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ISBN:
(纸本)9759845849
Negation is useful in the majority of the real world applications. However, its introduction leads to semantic and canonical problems. We propose in this paper an approach based on stratification to deal with negation problems. This approach is based on an extension of predicates nets. It is characterized with two main contributions. The first concerns the management of the whole class of stratified programs. The second contribution is related to usual operations optimizations on stratified programs (maximal stratification, incremental updates ...).
Negation is useful in the majority of the real world applications. However, its introduction leads to semantic and canonical problems. SEPN nets are well adapted extension of predicate nets for the definition and mani...
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ISBN:
(纸本)9759845849
Negation is useful in the majority of the real world applications. However, its introduction leads to semantic and canonical problems. SEPN nets are well adapted extension of predicate nets for the definition and manipulation of stratified programs. This formalism is characterized by two main contributions. The first concerns the management of the whole class of stratified programs. The second contribution is related to usual operations optimization (maximal stratification, incremental updates ...). We propose, in this paper, useful algorithms for manipulating stratified programs using SEPN. These algorithms were implemented and validated with STRPRO tool.
The evaluation of logic programs is traditionally implemented in monolithic systems that are general-purpose in the sense that they are able to process an entire class of programs. In this paper, we follow a different...
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ISBN:
(纸本)9783319701691;9783319701684
The evaluation of logic programs is traditionally implemented in monolithic systems that are general-purpose in the sense that they are able to process an entire class of programs. In this paper, we follow a different approach;we present a compilation procedure that is able to generate a problem-specific executable implementation of a given (non-ground) logic program. Our implementation follows a bottom-up evaluation strategy. Moreover, we implemented such procedure into a C++ tool and we present an experimental analysis that shows the performance benefits that can be obtained by a compilation-based approach.
In "Heterogeneous active agents, I" (Eiter et al., 1999), two of the authors have introduced techniques to build agents on top of arbitrary data structures, and to "agentize" new/existing programs....
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In "Heterogeneous active agents, I" (Eiter et al., 1999), two of the authors have introduced techniques to build agents on top of arbitrary data structures, and to "agentize" new/existing programs. They provided a series of successively more sophisticated semantics for such agent systems, and showed that as these semantics become epistemically more desirable, a computational price may need to be paid. In this paper, we identify a class of agents that are called weakly regular--this is done by first identifying a fragment of agent programs (Eiter et al., 1999) called weakly regular agent programs (WRAPs for short). It is shown that WRAPs are definable via three parameters--checking for a property called "safety", checking for a property called "conflict-freedom" and checking for a "deontic stratifiability" property. Algorithms for each of these are developed. A weakly regular agent is then defined in terms of these concepts, and a regular agent is one that satisfies an additional boundedness property. We then describe a polynomial algorithm that computes (under suitable assumptions) the reasonable status set semantics of regular agents--this semantics was identified by Eiter et al. (1999) as being epistemically most desirable. Though this semantics is coNP-complete for arbitrary agent programs (Eiter and Subrahmanian, 1999), it is polynomially computable via our algorithm for regular agents. Finally, we describe our implementation architecture and provide details of how we have implemented RAPs, together with experimental results. (C) 2000 Elsevier Science B.V. All rights reserved.
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