Equational Prover. EQP is an automated theorem proving program for first-order equational logic. Its strengths are good implementations of associative-commutative unification and matching, a variety of strategies for equational reasoning, and fast search. It seems to perform well on many problems about lattice-like structures. EQP is not as stable and polished as our main production theorem prover Otter. But it has obtained several interesting results, and we have decided to make it available (including the source code) to everyone, with no restrictions (and of course no warranty). EQP’s documentation is not good, but if you already know Otter, you might not have great difficulty in learning to use EQP.