Ontology language


In computer science and artificial intelligence, ontology languages are formal languages used to construct ontologies. They allow the encoding of knowledge about specific domains and often include reasoning rules that support the processing of that knowledge. Ontology languages are usually declarative languages, are almost always generalizations of frame languages, and are commonly based on either first-order logic or on description logic.

Classification of ontology languages

Classification by syntax

Traditional syntax ontology languages

These languages use a markup scheme to encode knowledge, most commonly with XML.

Frame-based

Three languages are completely or partially frame-based languages.
  • F-Logic
  • OKBC
  • KM

    Description logic-based

provides an extension of frame languages, without going so far as to take the leap to first-order logic and support for arbitrary predicates.
  • KL-ONE
  • RACER
  • OWL
Gellish is an example of a combined ontology language and ontology that is description logic-based. It distinguishes between the semantic differences among others of:
  • relation types for relations between concepts
  • relation types for relations between individuals
  • relation types for relations between individuals and classes
It also contains constructs to express queries and communicative intent.

First-order logic-based

Several ontology languages support expressions in first-order logic and allow general predicates.
  • Common Logic
  • CycL
  • FO-dot
  • KIF