Zuoquan Lin

Algorithms for Paraconsistent Reasoning with OWL

In an open, constantly changing and collaborative environment like the forthcoming Semantic Web, it is reasonable to expect that knowledge sources will contain noise and inaccuracies. Practical reasoning techniques for ontologies therefore will have to be tolerant to this kind of data, including the ability to handle inconsistencies in a meaningful way. For this purpose, we employ paraconsistent reasoning based on four-valued logic, which is a classical method for dealing with inconsistencies in knowledge bases. Its transfer to OWL DL, however, necessitates the making of fundamental design choices in dealing with class inclusion, which has resulted in differing proposals for paraconsistent description logics in the literature. In this paper, we build on one of the more general approaches which due to its flexibility appears to be most promising for further investigations. We present two algorithms suitable for implementation, one based on a preprocessing before invoking a classical OWL reasoner, the other based on a modification of the KAON2 transformation algorithms. We also report on our implementation, called ParOWL.

Measuring Inconsistency for Description Logics Based on Paraconsistent Semantics

In this paper, we present an approach for measuring inconsistency in a knowledge base. We first define the degree of inconsistency using a four-valued semantics for the description logic

A Tableau Algorithm for Handling Inconsistency in OWL

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An OWL-Based approach for RBAC with negative authorization

. Then an ordering over knowledge bases is given by considering their inconsistency degrees. Our measure of inconsistency can provide important information for inconsistency handling.

Towards a paradoxical description logic for the semantic web

In Semantic Web, the knowledge sources usually contain inconsistency because they are constantly changing and from different view points. As is well known, as based on the description logic, OWL is lack of the ability of tolerating inconsistent or incomplete data. Recently, the research in handling inconsistency in OWL becomes more and more important. In this paper, we present a paraconsistent OWL called quasi-classical OWL to handle inconsistency with holding important inference rules such as modus tollens, modus ponens, and disjunctive syllogism. We propose a terminable, sound and complete tableau algorithm to implement paraconsistent reasoning in quasi-classical OWL. In comparison with other approaches to handle inconsistency in OWL, our approach enhances the ability of reasoning by integrating paraconsistent reasoning with important classical inference rules.

An argumentation framework for description logic ontology reasoning and management

Access control is an important issue related to the security on the Semantic Web. Role-Based Access Control (RBAC) is commonly considered as a flexible and efficient model in practice. In this paper, we provide an OWL-based approach for RBAC in the Semantic Web context. First we present an extended model of RBAC with negative authorization, providing detailed analysis of conflicts. Then we use OWL to formalize the extended model. Additionally, we show how to use an OWL-DL reasoner to detect the potential conflicts in the extended model.

Inferring with inconsistent OWL DL ontology: a multi-valued logic approach

As a vision for the future of the Web, the Semantic Web is an open, constantly changing and collaborative environment. Hence it is reasonable to expect that knowledge sources in the Semantic Web contain noise and inaccuracies. However, as the logical foundation of Ontology Web Language in the Semantic Web, description logics fail to tolerate inconsistent information. The study of inconsistency handling in description logics is an important issue in the Semantic Web. One major approach to inconsistency handling is based on so-called paraconsistent reasoning, in which standard semantics is refined so that inconsistencies can be tolerated. Four-valued description logics are not satisfactory for the Semantic Web in that its reasoning is a bit far from standard semantics. In this paper, we present a paraconsistent description logic called paradoxical description logic, which is based on a three-valued semantics. Compared to existing paraconsistent description logics, our approach is more suitable for dealing with inconsistent ontologies in that paraconsistent reasoning under our semantics provides a better approximation to the standard reasoning. An important result in this paper is that we propose a sound and complete tableau for paradoxical description logics.

An Anytime Algorithm for Computing Inconsistency Measurement

This paper presents an argumentation framework for reasoning and management in (inconsistent or incoherent) description logic ontologies which contain conflicts. First, a new argumentation framework obtained by combining Besnard and Hunter’s framework with binary argumentation is introduced to frame the inner relation over axioms in an ontology. A dialogue mechanism, based on this framework, is then presented to derive meaningful consequences from inconsistent ontologies. Three novel operators are developed to repair those axioms or assertions which cause inconsistency or incoherency of ontologies by using this framework. Within this framework, an inconsistency is neither directly assigned a contradictory value nor roughly removed but further analyzed and evaluated. Because of this, reasoning within it satisfies some important logical properties such as consistency-preserving and justifiability. Moreover, it provides an alternative scenario for maintaining consistency and coherency of ontologies with giving consideration to both semantics and syntax. Thus the repaired results by using the proposed framework not only keep the closer semantics but also preserve the syntactic structure of original ontologies.

THE DATALOGDL COMBINATION OF DEDUCTION RULES AND DESCRIPTION LOGICS

Web ontology language OWL DL has two-valued model theory semantics so that ontologies expressed by it become trivial when contradictions occur. Based on classical description logic

An Algorithm for Computing Inconsistency Measurement by Paraconsistent Semantics

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