As it was already mentioned Object Oriented paradigm of knowledge representation is different from relational paradigm. Numerous efforts have been made to reconcile these two. One direction of these efforts is the development of object oriented extension for relational databases. Another direction is related to development of object -oriented logic programming systems. F-Logic is perhaps the most elegant theoretical result of the later work. F-Logic is a powerful logic programming system which naturally fits into Object Oriented paradigm. GFL provides XML based and graphical representation for F-Logic constructs. The availability of graphical and xml-based representation of F-Logic statements in GFL make it a perfect tool for developing ontologies. Here we will simultaneously introduce the basic concepts of F-Logic and GFL.
GFL is intended to be a framework for specification of ontologies and Model Based Mediation of heterogeneous data sources. Why not use a conventional Description Logic based approach? In our opinion, DL have three major shortcomings: 1) they use set theoretical semantic which is not as intuitive as Object Oriented Paradigm when we need to deal with constraints on object attributes; 2) native DL notations require set theoretical symbols which are not available in ASCII set; 3)most important shortcoming is that DL have extremely limited expressive power for queries. GFL is designed as a remedy for these three problems. Unlike DL, GFL supports arbitrarily complex queries. Although the introduction of the variables increases the complexity of the diagram language, this increase is not as significant as one may think of.
C 2003 S. Krivov Send your comments to skrivov@zoo.uvm.edu