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are considered one of the pillars of the Semantic Web , although they do not have a universally accepted definition. A (Semantic Web) can be considered as a special form of (usually light-weight) ontology, or sometimes also merely as a collection of URIs with an (usually informally) described meaning. Ontologies on semanticweb.org are usually assumed to be accompanied by some document in a formal ontology language , though some ontologies do not use standardised formats for that purpose.
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