The W3C OWL 2 recommendation is an ontology language for the Semantic Web. It allows defining both schema (i.e., entities, axioms, and expressions) and instances (i.e., individuals) of ontologies. OWL 2 ontologies are stored as Semantic Web documents. However, OWL 2 lacks explicit support for time-varying schema or for time-varying instances. Hence, knowledge engineers or maintainers of semantics-based Web resources have to use ad hoc techniques in order to specify OWL 2 schema for time-varying instances. In this paper, for a disciplined and systematic approach to the temporal management of Semantic Web documents, we propose the adoption of a framework called Temporal OWL 2 (tauOWL), which is inspired by the tauXSchema framework defined for XML data. In a way similar to what happens in tauXSchema, tauOWL allows creating a temporal OWL 2 ontology from a conventional (i.e., non-temporal) OWL 2 ontology and a set of logical and physical annotations. Logical annotations identify which elements of a Semantic Web document can vary over time; physical annotations specify how the time-varying aspects are represented in the document. By using annotations to integrate temporal aspects in the traditional Semantic Web, our framework (i) guarantees logical and physical data independence for temporal schemas and (ii) provides a low-impact solution since it requires neither modifications of existing Semantic Web documents, nor extensions to the OWL 2 recommendation and Semantic Web standards.
tauOWL: A Systematic Approach to Temporal Versioning of Semantic Web Documents
GRANDI, FABIO;
2014
Abstract
The W3C OWL 2 recommendation is an ontology language for the Semantic Web. It allows defining both schema (i.e., entities, axioms, and expressions) and instances (i.e., individuals) of ontologies. OWL 2 ontologies are stored as Semantic Web documents. However, OWL 2 lacks explicit support for time-varying schema or for time-varying instances. Hence, knowledge engineers or maintainers of semantics-based Web resources have to use ad hoc techniques in order to specify OWL 2 schema for time-varying instances. In this paper, for a disciplined and systematic approach to the temporal management of Semantic Web documents, we propose the adoption of a framework called Temporal OWL 2 (tauOWL), which is inspired by the tauXSchema framework defined for XML data. In a way similar to what happens in tauXSchema, tauOWL allows creating a temporal OWL 2 ontology from a conventional (i.e., non-temporal) OWL 2 ontology and a set of logical and physical annotations. Logical annotations identify which elements of a Semantic Web document can vary over time; physical annotations specify how the time-varying aspects are represented in the document. By using annotations to integrate temporal aspects in the traditional Semantic Web, our framework (i) guarantees logical and physical data independence for temporal schemas and (ii) provides a low-impact solution since it requires neither modifications of existing Semantic Web documents, nor extensions to the OWL 2 recommendation and Semantic Web standards.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
