Extending logic programming

Laenens, Els; Saccà, Domenico; Vermeir, Dirk

doi:10.1145/93597.98728

Cited by 23 publications

(4 citation statements)

References 8 publications

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“…The causal rejection principle is not novel-in fact, it constitutes a major ingredient of the well-known dynamic logic programming approach (Alferes et al, 1998;. Furthermore, it underlies, in slightly different forms, the related approaches of inheritance logic programs (Buccafurri et al, 1999a) and ordered logic programs (Laenens et al, 1990;Buccafurri et al, 1996). We provide here a simple and rigorous realization of this principle, in terms of "founded" rejection: a rule r may only be rejected by some other rule r ′ which itself is not rejected.…”

Section: Motivation and Contextmentioning

confidence: 99%

“…Inheritance programs are also related to ordered logic programs, due to Laenens et al (1990) and further analyzed by Buccafurri et al (1996). The difference between inheritance programs and ordered logic programs is that the latter ones have a builtin contradiction removal feature, which eliminates local inconsistencies in a given hierarchy of programs.…”

Section: Proofmentioning

confidence: 99%

See 1 more Smart Citation

On properties of update sequences based on causal rejection

Eiter¹,

Fink²,

Sabbatini³

et al. 2002

Theory and Practice of Logic Programming

191

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In this paper, we consider an approach to update nonmonotonic knowledge bases represented as extended logic programs under the answer set semantics. In this approach, new information is incorporated into the current knowledge base subject to a causal rejection principle, which enforces that, in case of conflicts between rules, more recent rules are preferred and older rules are overridden. Such a rejection principle is also exploited in other approaches to update logic programs, notably in the method of dynamic logic programming, due to Alferes et al.One of the central issues of this paper is a thorough analysis of various properties of the current approach, in order to get a better understanding of the inherent causal rejection principle. For this purpose, we review postulates and principles for update and revision operators which have been proposed in the area of theory change and nonmonotonic reasoning. Moreover, some new properties for approaches to updating logic programs are considered as well. Like related update approaches, the current semantics does not incorporate a notion of minimality of change, so we consider refinements of the semantics in this direction. As well, we investigate the relationship of our approach to others in more detail. In particular, we show that the current approach is semantically equivalent to inheritance programs, which have been independently defined by Buccafurri et al., and that it coincides with certain classes of dynamic logic programs, for which we provide characterizations in terms of graph conditions. In view of this analysis, most of our results about properties of the causal rejection principle apply to each of these approaches as well. Finally, we also deal with computational issues. Besides a discussion on the computational complexity of our approach, we outline how the update semantics and its refinements can be directly implemented on top of existing logic programming systems. In the present case, we implemented the update approach using the logic programming system DLV.

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Section: Motivation and Contextmentioning

confidence: 99%

Section: Proofmentioning

confidence: 99%

On properties of update sequences based on causal rejection

Eiter¹,

Fink²,

Sabbatini³

et al. 2002

Theory and Practice of Logic Programming

191

View full text Add to dashboard Cite

show abstract

“…Clearly, the capability to provide constructs for specifying exceptions in the context of an inheritance hierarchy makes the language intrinsically nonmonotonic. In essence, the BQM language (note that BQM is also used to name the language of the BQM system) is an an extension of Ordered Logic [16,18,19,201 to deal with objects and co-operation among objects.…”

Section: H E R M E S 1243 Have Been Developedmentioning

confidence: 99%

BQM: a system integrating logic, objects, and non-monotonic reasoning

Leone¹,

Rullo²

Proceedings of 7th IEEE International Conference on Tools With Artificial Intelligence

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The B Q M 1 system extends deductive database technology with knowledge structuring capabilities to provade an advanced environment for the development of data and knowledge-based applications. The system relies on a knowledge representation language that combines the declarativeness of logic programming with the notions of object, inheritance with exceptions, and message passing. Exceptions are supported b y allowing rules with negated heads. The use of exceptions inside the inheritance mechanism makes the language inherently nonmonotonic.The paper describes BQM focusing on both the language and the implementation techniques. A n informal overview of the language is first given. Then, a number of techniques for efficient query evaluation are presented. These techniques significantly extend "traditional" deductive database query evaluation strategies to deal with nonmonotonic reasoning. A description of the architecture of the current prototype of the BQM system is also given.

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“…To deal with these "structural" conflicts, we have devised two semantics as an extension of the well-founded and the stable model semantics of Logic Programming and Ordered Logic [7,8,15,17], each of which corresponds to a possible conflict interpretation. The former defines a conservative approach whereby only "sure" authorizations are derived (that is, those authorizations which are not derived from ambiguous sources), whereas the latter goes beyond ambiguities by providing a number of authorization sets, each of which represents a consistent set of access authorizations.…”

Section: Introductionmentioning

confidence: 99%

A logical framework for reasoning on data access control policies

Bertino

Buccafurri²,

Ferrari³

et al.

Proceedings of the 12th IEEE Computer Security Foundations Workshop

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In this paper we propose a logic formalism that naturally supports the encoding of complex security specifications. This formalism relies on a hierarchically structured domain made of subjects, objects and privileges.Authorizations are expressed by logic rules. The formalism supports both negation by failure (possibly unstratified) and true negation. The latter is used to express negative authorizations. It turns out that conflicts may result from a set of authorization rules. Dealing with such conflicts requires the knowledge of the domain structure, such as grantor priorities and object/subject hierarchies, which is used in the deductive process to determine which authorization prevails, if any, on the others. Often, however, conflicts are unsolvable, as they express intrinsic ambiguities.We have devised two semantics as an extension of the well-founded and the stable model semantics of logic programming. We have also defined a number of access policies, each based on two orthogonal choices: one is related to the way how we cope with multiplicity of authorization sets in case of stable model semantics; the other is concerned with the open/closed assumption. A comparative analysis of the proposed authorization policies, based on their degree of permissivity, shows that they form a complete lattice.

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Extending logic programming

Cited by 23 publications

References 8 publications

On properties of update sequences based on causal rejection

On properties of update sequences based on causal rejection

BQM: a system integrating logic, objects, and non-monotonic reasoning

A logical framework for reasoning on data access control policies

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