ACL2 Version 6.4
ACL2 is both a programming language in which you can model computer systems
and a tool to help you prove properties of those models.
ACL2 is part of the Boyer-Moore family of provers, for which its authors have
received the 2005 ACM
Software System Award.
Matt Kaufmann and J Strother Moore
University of Texas at Austin
January 9, 2014
Welcome to the ACL2 home page! We highlight a few aspects of ACL2:
- Libraries (Books).
Libraries of books (files containing
definitions and theorems) extend the code that we have written. The installation instructions explain
how to fetch the community books, which are contributed and maintained
by the members of the ACL2 community. For more information, see the
There is an
extensive user's manual for the ACL2 system, and an even more comprehensive
manual that documents not only the ACL2 system but also many community books.
See below to learn more.
- License and Copyright.
ACL2 is freely available under the terms
of the LICENSE file distributed with ACL2. License, copyright, and
authorship information is available from the ACL2 documentation.
The ACL2 distribution includes the following
extensions, which were developed by the individuals shown.
Another extension of ACL2 is the Eclipse-based ACL2 Sedan (ACL2s). Unlike
the systems above, ACL2s is distributed and maintained by Pete Manolios and his
research group. ACL2s comes with a standard executable ACL2 image for Windows,
but it also comes with pre-certified community books and an extension of ACL2
with additional features, including extra automation for termination proofs as
well as counterexample generation.
Support for the real numbers by way of non-standard analysis
Support for hash cons, applicative hash tables, and function
memoization for reuse of previously computed results
Bob Boyer, Warren A. Hunt, Jr., Jared Davis, and Sol Swords
Support for parallel evaluation
David L. Rager
We gratefully acknowledge substantial support from the following. (These are
included in a much more complete acknowledgments page.)
- National Science Foundation
- This material is based upon work supported by the National Science
Foundation under Grant Nos. EIA-0303609, CNS-0429591, ISS-0417413,
CCF-0945316, and CNS-0910913.
- Any opinions, findings and conclusions or recomendations expressed in
this material are those of the authors and do not necessarily reflect the
views of the National Science Foundation.
- Advanced Micro Devices, Inc.
- ForrestHunt, Inc.
- Rockwell Collins, Inc.
- Sun Microsystems, Inc.
ACL2's user manual is a vast hypertext document. If you are a newcomer to
ACL2, we do not recommend that you wander off into the full
documentation. Instead start with the ACL2-TUTORIAL
documentation topic. Experienced users tend mostly to use the manual as a
reference manual, to look up concepts mentioned in error messages or vaguely
remembered from their past experiences with ACL2.
The ACL2+books combined manual includes not only ACL2 User's Manual, but
also documents many of the community books (libraries).
This manual, which is written by many authors, is thus more extensive than the
ACL2 system, and thus potentially more useful.
The following links take you to these two manuals. The manuals can however be
read not only in a Web browser, but in the ACL2-Doc Emacs
browser or by using the ACL2
at the terminal; see the documetation topic,
Once you have installed ACL2, you can browse the ACL2 User's Manual locally by
opening the home page in your browser to view the file
doc/home-page.html in your ACL2 sources directory.
A companion to ACL2 is the library of community books, which have
been developed by many users over the years. These books contain definitions
and theorems that you might find useful in your models and proofs. In
addition, some books contain ACL2 reasoning or analysis tools built by users.
The installation instructions
explain how to download and
install the community books.
We strongly encourage users to submit additional books or improve existing
books, by following the instructions at the acl2-books project page. In
particular, the community book
contains the ACL2 system documentation. Members of the acl2-books project are
welcome to edit that book in order to improve the system documentation.
We also distribute a few interface
tools. For these, see the Utilities
Books and Papers about ACL2 and Its Applications. Some of the
papers mentioned in that collection contain utilities, scripts, or
ACL2 books for the problem domains in question.
The links below may help you to search the ACL2 documentation and the ACL2
community books, respectively.