Web Ontology Languages

The recognition of the key role that ontologies are likely to play in the future of the We
the extension of Web markup languages in order to facilitate content description and the
of Web based ontologies, e.g., XML Schema,
1 RDF2 (Resource Description Framework
Schema [7]. RDF Schema (RDFS) in particular is recognisable as an ontology/knowledge re
language: it talks about classes and properties (binary relations), range and domain con
properties), and subclass and subproperty (subsumption) relations.
RDFS is, however, a very primitive language (the above is an almost complete descr
functionality), and more expressive power would clearly be necessary/desirable in order
resources in sucient detail. Moreover, such descriptions should be amenable to automat
if they are to be used eectively by automated processes, e.g., to determine the semantic
between syntactically dierent terms.
The recognition of these requirements has led to the development of DAML+OIL, a
Web ontology language. DAML+OIL is the result of a merger between DAML-ONT
developed as part of the US DARPA Agent Markup Language (DAML) programme3) a
Ontology Inference Layer) [9], developed by a group of (mostly) European researchers.
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