A Flexible System for Constraint Disjunctive Logic Programming

Constraint logic programming combines Horn-clause logic and constraint reasoning. However, the specification of many problems often requires disjunctive, i.e. non-Horn rules in addition. There are approaches proposing such an extension of logic programming, but first and foremost they provide theoretical frameworks only. Here, we want to introduce a method which is also well-suited for implementation, namely constraint model elimination. It can be seen as a powerful programming language for positive disjunctive logic programs. Hence, we state not only refutational, but answer-completeness of our calculus in this paper. The main idea of the implementation is to compile the logical part of a problem specification into Prolog (using the so-called PTTP-technique) and to exploit existing constraint solvers (available with many Prolog systems nowadays). The whole approach is integrated into the Protein theorem prover. We also consider some applications for this approach, e.g. analysing rule sets.