  OTTER is a resolution-style theorem-proving program for first-order logic
with equality. OTTER includes the inference rules binary resolution,
hyperresolution, UR-resolution, and binary paramodulation. Some of its other
abilities and features are conversion from first-order formulas to clauses,
forward and back subsumption, factoring, weighting, answer literals, term
ordering, forward and back demodulation, evaluable functions and predicates,
Knuth-Bendix completion, and the hints strategy. OTTER is coded in ANSI C, is
free, and is portable to many different kinds of computer.
