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On the Semantics of Linking and Importing in Modular Ontologies


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Bao, Jie, Caragea, Doina and Honavar, Vasant (2006) On the Semantics of Linking and Importing in Modular Ontologies. Technical Report, Computer Science, Iowa State University.

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Abstract

While the idea of a universal upper ontology is gradually abandoned on the Semantic Web because of the autonomous and distributed nature of different components on the Web, the research community realized that ontologies on the Web, instead of being centralized and monolithic, will be modular, collaboratively built and partially connected. However, the current web ontology language OWL provides only limited supports for the modularity of ontologies, therefore also fails to support localized semantics, partial reusability, selective knowledge hiding, scaleable distributed knowledge representation and organizational structures of ontologies. As a result, recent years saw increasing efforts on the study of formalisms of modular ontologies, such as, Fusion of Abstract Description Systems, Distributed Description Logics (DDL), E-connections and Package-extended Description Logics (P-DL). Serafini, Stickenschmidt et.al. (2005) presented a formal comparison of several modular ontology languages, including DDL and E-connections, by reducing them to the Distributed First Order Logics (DFOL) framework. However, their work only addresses the semantics of "mappings", or "linkings", between different ontology modules. On the other hand, OWL and P-DL adopt another approach, i.e., "importing", to build semantic relations between different ontologies modules, of which the formal investigation of its semantics is still an open problem. The major difference between the two approaches is on the usage of foreign terms in ontology modules. In a linked ontology, different modules have disjoint terminologies and disjoint interpretation domains, and semantic relations between ontology modules are only enabled by a set of mapping axioms, such as bridge rules in DDL or E-connections. On the contrast, the importing approach allows direct references to terms defined in other ontology modules, or in other words, allows the importing of foreign terms. Against this background, we compare the semantics of the two approaches under the DFOL framework, with the study of their strengthes and limitations. Such an investigation reveals that, while the linking approach is appealing when disjoint ontology modules is possible, the importing approach has its advantages of stronger expressivity, precise semantic connections and more direct language implementation, in more general application scenarios.

Subjects:Computing Methodologies: ARTIFICIAL INTELLIGENCE: Knowledge Representation Formalisms and Methods (F.4.1)
ID code:00000408
Deposited by:Jie Bao on 15 March 2006

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