| |||
|
Resource Description Framework (RDF) Model Theory A model-theoretic semantics for a language assumes that the language refers to a 'world', and describes the minimal conditions that a world must satisfy in order to assign an appropriate meaning for every expression in the language. A particular world is called an interpretation, so that model theory might be better called 'interpretation theory'. The idea is to provide an abstract, mathematical account of the properties that any such interpretation must have, making as few assumptions as possible about its actual nature or intrinsic structure. Model theory tries to be metaphysically and ontologically neutral. It is typically couched in the language of set theory simply because that is the normal language of mathematics - for example, this semantics assumes that names denote things in a set IR called the 'universe' - but the use of set-theoretic language here is not supposed to imply that the things in the universe are set-theoretic in nature. RDFMT describes a model theory for RDF and RDFS which treats the language as simple assertional language, in which each triple makes a distinct assertion and the meaning of any triple is not changed by adding other triples. This imposes a fairly strict monotonic discipline on the language, so that it cannot express closed world assumptions, local default preferences, and several other commonly-used non-monotonic constructs. There are several aspects of meaning in RDF which are ignored by this semantics; in particular, it treats URIs as simple names, ignoring aspects of meaning encoded in particular URI forms (RFC 2396) and does not provide any analysis of time-varying data or of changes to URI denotations. |
