Catálogo de publicaciones - libros

The well-founded semantics (WFS) for logic programs is one of the few major paradigms for closed-world reasoning. With the advent of the Semantic Web, it is being used as part of rule systems for ontology reasoning, and also investigated as to its usefulness as a semantics for hybrid systems featuring combined open- and closed-world reasoning. Even in its most basic form, however, the WFS is undecidable. In fact, it is not even semi-decidable, which means that it is a theoretical impossibility that sound and complete reasoners for the WFS exist.

Surprisingly, however, this matter has received next to no attention in research, although it has already been shown in 1995 by John Schlipf [1]. In this paper, we present several conditions under which query-answering under the well-founded semantics is decidable or semi-decidable. To the best of our knowledge, these are the very first results on such conditions.

We present a vision of smart, goal-oriented web services that reason about other services’ policies and evaluate the possibility of future interactions. We assume web services whose behavioural interface is specified in terms of reactive rules. Such rules can be made public, in order for other web services to answer the following question: “is it possible to inter-operate with a given web service and achieve a given goal?”. In this article we focus on the underlying reasoning process, and we propose a declarative and operational abductive logic programming-based framework, called WAV. We show how this framework can be used for a-priori verification of web services interaction.

We present a novel approach to fuzzy dl-programs under the answer set semantics, which is a tight integration of fuzzy disjunctive programs under the answer set semantics with fuzzy description logics. From a different perspective, it is a generalization of tightly integrated disjunctive dl-programs by fuzzy vagueness in both the description logic and the logic program component. We show that the new formalism faithfully extends both fuzzy disjunctive programs and fuzzy description logics, and that under suitable assumptions, reasoning in the new formalism is decidable. Furthermore, we present a polynomial reduction of certain fuzzy dl-programs to tightly integrated disjunctive dl-programs. We also provide a special case of fuzzy dl-programs for which deciding consistency and query processing have both a polynomial data complexity.

Expressing rules in controlled natural language can bring us closer to the vision of the Semantic Web since rules can be written in the notation of the application domain and are understandable by anybody. AceRules is a prototype of a rule system with a multi-semantics architecture. It demonstrates the formal representation of rules using the controlled natural language ACE. We show that a rule language can be executable and easily understandable at the same time. AceRules is available via a web service and two web interfaces.

This paper proposes a solution for bridging abstract and concrete syntax of a Web rule language by using model transformations. Current specifications of Web rule languages such as Semantic Web Rule Language (SWRL) define its abstract syntax (e.g., EBNF notation) and concrete syntax (e.g., XML schema) separately. Although the recent research in the area of Model-Driven Engineering demonstrates that such a separation of two types of syntax is a good practice (due to the complexity of languages), one should also have tools that check validity of rules written in a concrete syntax with respect to the abstract syntax of the rule language. In this study, we use analyze the REWERSE I1 Rule Markup Language (R2ML) whose abstract syntax is defined by using metamodeling, while its textual concrete syntax is defined by using XML schema. We bridge this gap by a bi-directional transformation defined in a model transformation language (i.e., ATL).

Web queries have been and will remain an essential tool for accessing, processing, and, ultimately, reasoning with data on the Web. With the vast data size on the Web and Semantic Web, reducing costs of data transfer and query evaluation for Web queries is crucial. To reduce costs, it is necessary to narrow the data candidates to query, simplify complex queries and reduce intermediate results.

This article describes a static approach to optimization of web queries. We introduce a set of rules which achieves the desired optimization by schema and type based query rewriting. The approach consists in using schema information for removing incompleteness (as expressed by ‘descendant’ constructs and disjunctions) from queries. The approach is presented on the query language Xcerpt, though applicable to other query languages like XQuery. The approach is an application of rules in many aspects—query rules are optimized using rewriting rules based on schema or type information specified in grammar rules.

So far several methods have been proposed for clustering the web. On the other hand, many algorithms have been developed for clustering the relational data, but their usage for the Web is to be investigated. One main category of such algorithms is density based methods providing high quality results. In this paper first, a new density based algorithm is introduced and then it is compared with other algorithms of this category. The proposed algorithm has some interesting properties and capabilities such as hierarchical clustering and sampling, making it suitable for clustering the web data.

After quantization and classification of the deviations between TM and ETM+ images based on approved thresholds, a correlation analysis method for the compared calibration is suggested in this paper. Four time points of raster data for 15 years of the highest group of land surface temperature and the lowest group of vegetation of the Kunsan city, are observed and analyzed their correlations for the change detection of urban land cover. This experiment detected strong and proportional correlation relationship between the highest group of land surface temperature and the lowest group of vegetation index which exceeded R=(+)0.9478, so the proposed correlation analysis model between land surface temperature and vegetation will be able to give proof an effective suitability to the land cover change detection and monitoring.

The paper presents an architecture and implementation techniques for hybrid integration of normal clauses under well-founded semantics with ontologies specified in Description Logics. The described prototype uses XSB Prolog both for rule reasoning and for controlling communication with the ontology reasoner RacerPro. The query answering techniques for hybrid rules implemented in this prototype are sound wrt. the declarative semantics, extending the well-founded semantics of normal programs and are faithful wrt. FOL.

This paper presents an extension to the Semantic Web Rule Language and a methodology to enable advanced mathematical support in SWRL rules. This solution separates mathematical and problem semantics allowing the inclusion of integration, differentiation and other operations not built-in to SWRL. Using this approach, it is possible to create rules to cope with complex scenarios that include mathematical relationships and formulas that exceed the SWRL capabilities.