Dipartimento di Informatica, Universitàegli Studi di Bari, Via Orabona 4, 70125 Bari, Italy
We focus on the induction and revision of terminologies from metadata. Following a Machine Learning approach, this setting can be cast as a search problem to be solved employing operators that traverse the search space expressed in a structural representation, aiming at correct concept definitions. The progressive refinement of such definitions in a terminology is driven by the available extensional knowledge (metadata). A knowledge-intensive inductive approach to this task is presented, that can deal with on the expressive Semantic Web representations based on Description Logics, which are endowed with well-founded reasoning capabilities. The core inferential mechanism, based on multilevel counterfactuals, can be used for either inducing new concept descriptions or refining existing (incorrect) ones. The soundness of the approach and its applicability are also proved and discussed.
University of Southampton, Southampton, UK
SRI International, Menlo Park, California, USA
IT Innovation, Southampton, UK
A central requirement for achieving the vision of run-time discovery and dynamic composition of services is the provision of appropriate descriptions of the operation of a service, that is, how the service interacts with agents or other services. In this paper, we use experience gained through the development of real-life Grid applications to produce a set of requirements for such descriptions and then attempt to match those requirements against the offerings of existing work, such as OWL-S and IRS-II. Based on this analysis we identify which requirements are not addressed by current research and, in response, produce a model for describing the interaction protocol of a service in response. The main contributions of this model are the ability to describe the interactions of multiple parties with respect to a single service, distinguish between interactions initiated by the service itself and interactions that are initiated by clients or other cooperating services, and capture within the description service state changes relevant to interacting parties that are either a result of internal service events or interactions. The aim of the model is not to replace existing work, since it only focuses on the description of the interaction protocol of a service, but to inform the further development of such work.
Department of Computer Science, University of Manchester, Oxford Road Manchester, United Kingdom M13 9PL
IBM T. J. Watson Research Center, 1 Rogers Street Cambridge, MA 02142, USA
Life science researchers increasingly rely on the web as a primary source of data, forcing them to apply the same rigor to its use as to an experiment in the laboratory. The myGrid project is developing the use of workflows to explicitly capture web-based procedures, and provenance to describe how and why results were produced. Experience within myGrid has shown that this provenance metadata is formed from a complex web of heterogenous resources that impact on the production of a result. Therefore we have explored the use of Semantic Web technologies such as RDF, and ontologies to support its representation and used existing initiatives such as Jena and LSID, to generate and store such material. The effective presentation of complex RDF graphs is challenging. Haystack has been used to provide multiple views of provenance metadata that can be further annotated. This work therefore forms a case study showing how existing Semantic Web tools can effectively support the emerging requirements of life science research.
Institute AIFB, University of Karlsruhe, D-76128 Karlsruhe
This paper introduces a visual, UML-based notation for OWL ontologies. We provide a standard MOF2 compliant metamodel which captures the language primitives offered by OWL DL. Similarly, we invent a UML profile, which allows to visually model OWL ontologies in a notation that is close to the UML notation. This allows to develop ontologies using UML tools. Throughout the paper, the significant differences to some earlier proposals for a visual, UML-based notation for ontologies are discussed.
Maryland Information and Network Dynamics Laboratory, USA
Department of Computer Science, University of Valencia, Spain
The standardization of the second generation Web Ontology Language, OWL, leaves a crucial issue for Web-based ontologies unsatisfactorily resolved: how to represent and reason with multiple distinct, but linked, ontologies. OWL provides the owl:imports construct which, roughly, allows Web ontologies to include other Web ontologies, but only by merging all the linked ontologies into a single logical "space." Recent work on multidimensional logics, fusions and other combinations of modal logics, distributed and contextual logics, and the like have tried to find formalisms wherein knowledge bases (and their logic) are kept more distinct but yet affect each other. These formalisms have various degrees of robustness in their computational complexity, their modularity, their expressivity, and their intuitiveness to modelers. In this paper, we explore a family of such formalisms, grounded in E-connections as extensions to OWL, with emphasis on a novel sub-formalism that seems very straightforward to implement on existing tableau OWL reasoners, as witnessed by our implementation of this formalism in the OWL reasoner Pellet. We discuss how to integrate those formalisms into OWL, as well as some of the issues that modelers have to face when using such formalisms in the context of a large number of heterogeneous, independently developed, richly interconnected ontologies that we expect to be the norm on the Semantic Web.
Department of Computer Science, University of Maryland, College Park, MD 20742, USA
MIND Lab, University of Maryland, 8400 Baltimore Ave., College Park, MD 20742, USA
Hierarchical Task-Network (HTN) based planning techniques have been applied to the problem of composing Web Services, especially when described using the OWL-S service ontologies. Many of the existing Web Services are either exclusively information providing or crucially depend on information-providing services. Thus, many interesting service compositions involve collecting information either during execution or during the composition process itself. In this paper, we focus on the latter issue. In particular, we present ENQUIRER, an HTN-planning algorithm designed for planning domains in which the information about the initial state of the world may not be complete, but it is discoverable through plan-time information-gathering queries. We have shown that ENQUIRER is sound and complete, and derived several mathematical relationships among the amount of available information, the likelihood of the planner finding a plan, and the quality of the plan found. We have performed experimental tests that confirmed our theoretical results and that demonstrated how ENQUIRER can be used in Web Service composition.
Last modified: June 26, 2006; Boanerges Aleman-Meza
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