G-KARL: A Graphical, Formal, and Executable Specification Language

In this paper we present the language G-KARL. G-KARL allows to describe the static, the functional and the dynamic view to a knowledge based system (kbs) graphically. This graphical representation makes the communication between the expert and the knowledge engineer easier. The underlying conceptual model for G-KARL is derived from the KADS model of expertise. Every primitive of G-KARL may be mapped to a language primitive of the language KARL (Knowledge Acquisition and Representation Language). KARL is a formal language, so every primitive of G-KARL has a defined formal semantics. KARL is an executable language, so G-KARL is also executable which supports the validation of the model of expertise by testing and thus allows the model of expertise to be built by prototyping. G-KARL allows to visualize the execution of this model which additionally supports the validation process. While G-KARL contains well established graphical means for the different views like the OMT-notation for the static view, data flow diagrams for the functional view and program flow diagrams for the dynamic view, G-KARL also offers new graphical primitives for specifying elementary inference actions within data flow diagrams and for specifying sufficient and necessary conditions within the static view. In KARL these model elements are described by L-KARL, a logical language enriched by additional modeling primitives.