An Implementation of the Model Elimination Proof Procedure

The model elimination (ME) and resolution algorithms for mechanical theorem-proving were implemented so as to maximize shared features. The identical data structures and large amount of common programming permit meaningful comparisons when the two programs are run on standard problems. ME does better on some classes of problems, and resolution better on others. The depth-first search strategy used in this ME implementation affects the performance profoundly. Other novel features in the implementation are new control parameters to govern extensions, and modified rules for generating and rejecting chains. The resolution program incorporates unit preference and set-of-support. An appendix reproduces the steps of a machine-derived ME refutation.