Structured data in structured logic programming environment

EPSILON, a prototype developed in the context of the European ESPRIT project, is discussed. It is built on top of a commercial Prolog and DBMS (database management system) running on standard UNIX environment. The EPSILON logic programming environment allows the structuring of large knowledge bases expressed in logic languages using so-called theories. The integration of different object-oriented concepts into the current EPSILON prototype provides an environment offering the user object-oriented concepts at different levels. First, the theory concept itself is an object-oriented mechanism to structure logic programs. Second, implementing logic languages, including object-oriented concepts (type hierarchies, nested data structures, etc.), by metaprogramming provided by the theory concept allows the user to employ different augmented logic languages within the programming environment