The SKOS (Simple Knowledge Organization System) Core is a model for representing thesauri and similar types of knowledge organization systems as RDF graphs. Although it provides a basic framework for building concept schemes, SKOS does not carry the strictly defined semantics of formal ontology languages and thus has a number of shortcomings to fully port existing schemes to the Semantic Web. This paper introduces a mapping of SKOS metadata to an ontology-based intermediate model, whose main

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... is to foster the semantic interoperability of different concept schemes. It has been achieved through the introduction of a common ground for the definition of concepts, based on the use of shared definitions already included in widely-used upper ontologies. This effort makes use of an upper ontology in particular: OpenCyc, the open source version of Cyc, which is currently one of the most complete general knowledge bases.