Description:

This package provides the Prover9 resolution/paramodulation theorem prover
and the Mace4 countermodel generator.

Prover9 is an automated theorem prover for first-order and equational logic.
It is a successor of the Otter prover. Prover9 uses the inference techniques
of ordered resolution and paramodulation with literal selection.

The program Mace4 searches for finite structures satisfying first-order and
equational statements, the same kind of statement that Prover9 accepts. If
the statement is the denial of some conjecture, any structures found by
Mace4 are counterexamples to the conjecture.

Mace4 can be a valuable complement to Prover9, looking for counterexamples
before (or at the same time as) using Prover9 to search for a proof. It can
also be used to help debug input clauses and formulas for Prover9.