Frame Logic (abbreviated F- Logic ) is a formal language for knowledge representation. F logic combines the advantages of the conceptual modeling of which object-oriented frame -based languages ​​and provides declarative, a compact and simple syntax and semantics of a well-defined logic -based language. F- Logic supports typing, meta- reasoning, complex objects, methods, classes, inheritance, rules, queries and modularization. The semantics of F -Logic is based on the semantics of first-order logic, especially on the semantics of logic programming.

F- Logic was developed by Michael Kifer at New York State University and Georg Lausen at the University of Mannheim. F- Logic is originally developed in the field of deductive databases will take place today but especially in the areas of semantic technologies, semantic web its use. F- Logic represents a language for the formulation of ontologies like OWL, RDF dar.

For F- Logic, a development environment is being developed in the European project NEON. F- Logic is now also used in numerous industrial applications for information integration, support for complex decisions, for finding solutions in customer service and in semantic search.


The following is a small example of F- Logic is given in the original language specification:

Schema / classes / methods

Man :: person. / / Every man is a person

Woman :: person. / / Every woman is a person

Person [ hatSohn = >> man ]. / / The son of a person is a man

Rules / derivatives

FORALL X, YX: person [ hatVater -> Y ] <- Y: man [ hatSohn -> X]. / / If X is the son of Y, Y is the father of X


Brad: man.

Angelina: woman.

Married ( brad, angelina ).

Brad [ hatSohn - >> { maddox, pax }].


With whom Angelina has a son named Pax?

FORALL M <- married (M, angelina ) AND M [ hatSohn - >> pax { }].

Meanwhile, the syntax has been simplified in some points.

F- Logic -based languages

  • FLORA -2 is an extension of the F- logic and transactional logic to HiLog
  • FLORID is an implementation in C
  • Ontobroker supports Object Logic the successor of F -Logic
  • Web Services Modeling Language ( WSML )
  • Semantic Web Services Language ( SWSL )