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.

	Start Here: Applications, Tours, and Tutorials/Demos		ACL2 Workshops, UT Seminar, and Course Materials
	Publications about ACL2 and Its Applications		The User's Manual and Hyper-Card
	Community Books: Lemma Libraries and Utilities		Mailing Lists
	Recent changes to this page		Obtaining, Installing, and License
	Differences from Version 6.3		Other Releases

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 acl2-books project page.
Documentation.
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.
Extensions.
The ACL2 distribution includes the following extensions, which were developed by the individuals shown.
- ACL2(r)
  Support for the real numbers by way of non-standard analysis
  Ruben Gamboa
- ACL2(h)
  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
- ACL2(p)
  Support for parallel evaluation
  David L. Rager
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.

We gratefully acknowledge substantial support from the following. (These are included in a much more complete acknowledgments page.)

DARPA
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.

The User's Manual

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 :DOC command at the terminal; see the documetation topic, DOCUMENTATION.

ACL2 user manual
ACL2+books combined manual
ACL2+books combined manual for "bleeding edge" distributions

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.

Community Books: Lemma Libraries and Utilities, and How to Contribute

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 books/system/doc/acl2-doc.lisp 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 section of 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.

Searching documentation and books

The links below may help you to search the ACL2 documentation and the ACL2 community books, respectively.

The web views of The ACL2 User's Manual and acl2+books combined manual allow you to search the short strings of the documentation (which are typically summaries of a line or so). To search the full content for a string or regular expression, you may use the Emacs-based ACL2-Doc browser.
The link below will take you to the community books website (which is external to the present ACL2 website), specifically to the section entitled ``Searching and browsing the books.'' There, you will see a search box in which you can enter your search term. For example, if you type `tail recursion' and then <RETURN>, you will see text from several books in the svn trunk that deal with the topic of tail recursion, with an accompanying ``File Path'' shown at the end of each book's text.
SEARCH THE COMMUNITY BOOKS