Schema definition concepts

All those concepts are defined in [2], the second document of the W3C, to allow the definition of schemas, that is, vocabularies of resources to use with RDF. Not all agents will need to be aware of these concepts : specialized agents, limited to using a predefined vocabulary, will not.

In schemas, new resources can be defined as specialization of old ones, thus allowing to infer implicit triples. Schemas also constrain the context in which defined resources may be used, inducing the notion of schema validity. We will see that those two notions can be seen as one, in a point of view based on first-order logic. They all can be expressed as rules allowing to infer new facts (basically, new triples or negations of triples). In these rules, the 3-ary logical predicate $\mathcal{T}(subject,\:predicate,\:object)$ will be used to represent a believed triple.