F-logic - F-logic Syntax

F-logic Syntax

Classes and individuals may be defined in F-logic as follows

man::person. woman::person. brad:man. angelina:woman.

This states, that "men and women are people" and that "Brad is a man", and "Angelina is a woman".

Statements about classes and individuals may be made as follows

person. brad. married(brad,angelina).

This defines that "the son of a person is a man", "Maddox and Pax are the sons of Brad" and "Brad and Angelina are married". Note that ->> is used for sets of values.

In addition it is possible to represent axioms in the F-logic in the following manner

man(X) <- person(X) AND NOT woman(X). FORALL X, Y <- X:person.

These mean "X is a man if X is a person but not a woman" and "if X is the son of Y then Y is the father of X".

In contrast to description logic based ontology formalism the semantics of F-logic are normally that of a closed world assumption as opposed to DL's open world assumption. Also, F-logic is generally undecidable, whereas the SHOIN description logic that OWL DL is based on is decidable. However it is possible to represent more expressive statements in F-logic that are not possible with description logics.