Transforming General Program Proofs A Meta Interpreter which Expands Negative Literals

This paper provides a method for generating a proof tree from an instance and a general logic program viz one which includes negative literals The method di ers from previous work in the eld in that negative literals are rst unfolded and then transformed using De Morgan s laws so that the tree explicitly includes negative rules The method is applied to a real world example a large executable speci cation providing rules for separation for two aircraft Given an instance of a pair of aircraft whose ight paths potentially violate seperation rules the tree contains both positive and negative rules which contribute to the proof