Despite most of the information available in the Semantic Web (SW) is context dependent, there is a lack of mechanism to qualify knowledge with the context in which it is supposed to hold. In the current practice, contextual information is often crafted in the ontology identifier or in the annotations, non of which affects reasoning. Extensions of the SW languages with specific mechanisms that allow to qualify knowledge, e.g., w.r.t. its provenance or w.r.t. time and events, were proposed, however, a widely accepted approach has not yet been reached. We propose a framework called Contextualized Knowledge Repository (CKR), build on top of the expressive description logic SROIQ. A CKR knowledge base is composed of DL knowledge bases, called contexts, each qualified by a set of contextual attributes that specify the boundaries within which the knowledge base is assumed to be true. Contexts are organized by a hierarchical coverage relation that regulates the propagation of knowledge between them. The paper defines the syntax and semantics of CKR; shows that concept satisfiability and subsumption are decidable with the complexity upper bound of 2NEXPTIME (i.e., same as for SROIQ); and finally it provides a sound and complete Natural Deduction calculus that characterizes the propagation of knowledge between contexts.
Contextual Representation and Reasoning with Description Logics
Serafini, Luciano;Homola, Martin
2011-01-01
Abstract
Despite most of the information available in the Semantic Web (SW) is context dependent, there is a lack of mechanism to qualify knowledge with the context in which it is supposed to hold. In the current practice, contextual information is often crafted in the ontology identifier or in the annotations, non of which affects reasoning. Extensions of the SW languages with specific mechanisms that allow to qualify knowledge, e.g., w.r.t. its provenance or w.r.t. time and events, were proposed, however, a widely accepted approach has not yet been reached. We propose a framework called Contextualized Knowledge Repository (CKR), build on top of the expressive description logic SROIQ. A CKR knowledge base is composed of DL knowledge bases, called contexts, each qualified by a set of contextual attributes that specify the boundaries within which the knowledge base is assumed to be true. Contexts are organized by a hierarchical coverage relation that regulates the propagation of knowledge between them. The paper defines the syntax and semantics of CKR; shows that concept satisfiability and subsumption are decidable with the complexity upper bound of 2NEXPTIME (i.e., same as for SROIQ); and finally it provides a sound and complete Natural Deduction calculus that characterizes the propagation of knowledge between contexts.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
