ACL2 is a logic and programming language in which you can model
computer systems, together with a tool to help you prove properties of
those models. "ACL2" denotes "A Computational Logic for Applicative
Common Lisp". ACL2 is part of the Boyer-Moore family of provers, for
which its authors have received the 2005 ACM Software System Award

There is some support for Emacs >24 in /opt/acl2/books/emacs/
