Page "Knowledge representation and reasoning" Paragraph 38

After CycL, a number of ontology languages have been developed.

Most are declarative languages, and are either frame languages, or are based on first-order logic.

Most of these languages only define an upper ontology with generic concepts, whereas the domain concepts are not part of the language definition.

These languages all use special-purpose knowledge engineering because as stated by Tom Gruber, " Every ontology is a treaty-a social agreement among people with common motive in sharing.

" There are always many competing and differing views that make any general purpose ontology impossible.

A general purpose ontology would have to be applicable in any domain and different areas of knowledge need to be unified.

Gellish English is an example of an ontological language that includes a full engineering English Dictionary.