OWL

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OWL (Web Ontology Language) is a family of notations for expressing properties of an RDF ontology, which vary in expressive power. The simplest, OWLlite, can express whether instances of a class should have particlar properties (say that animals have a number of legs) or that a class is a sub-class of another (e.g. Dalmation is a kind of dog). More complex variants allow oen to declare, for example, that a class can only have a fixed set of instances, or to use levels of meta-modelling where classes can be treated as instances. In general, simpler variants are easier to deal with and check computationally, but are less expressive.

Used on Chap. 17: page 395; Chap. 18: page 435

Also known as web ontology language