ACL2 System and Community Books
===============================

The ACL2 theorem proving environment consists of two parts: The ACL2
System and The ACL2 Books.  This repository contains both.

### ACL2 System

The included version of the ACL2 System is the latest, under-development
version of the [ACL2 Theorem Prover][ACL2].  It is updated only by the
ACL2 authors, Matt Kaufmann and J Moore.

[ACL2]: http://www.cs.utexas.edu/users/moore/acl2 "ACL2 Home Page"

### ACL2 Books

The `books/` directory of this repository comprises the Community Books,
which are the canonical collection of open-source libraries for the ACL2
System.  As the name suggests, they are updated by the ACL2 community.

### Documentation

- The [Combined ACL2 + Books Manual][dev-manual] is updated frequently
  to track the latest changes to this repository.

- If you are instead using official, released Version 8.6 of ACL2, see
  the [Version 8.6 Manual][release-manual] instead.

Each of these manuals can be downloaded for offline use by clicking the
download button on the right hand side of the upper toolbar while
browsing the manual.

[release-manual]: http://www.cs.utexas.edu/users/moore/acl2/current/combined-manual/index.html
[dev-manual]:  https://www.acl2.org/doc/index.html

### Obtaining the Source Code

While active development of ACL2 occurs at the `acl2/acl2` repo on
GitHub, stable releases are officially distributed from the
`acl2-devel/acl2-devel` fork, which exists for that purpose.

#### Latest Stable Release

You can download a gzipped tarfile or zip file for the latest release,
which includes the [ACL2 system][ACL2] and the [community
books][community books], from [the releases page][releases] on GitHub.

Alternatively you can obtain a copy of the latest release using
[`git`][git].  For example, do the following in a fresh directory
(note the "." at the end).

```
git clone -b 8.6 https://github.com/acl2-devel/acl2-devel .
```

The new directory `/path/to/somewhere/acl2/` will now contain a copy of
ACL2 Version 8.6.  Please see the [ACL2 home page][ACL2], specifically
its [installation instructions][installation], for how to build an
executable and certify books in your new directory.

[ACL2]:            http://www.cs.utexas.edu/users/moore/acl2 "ACL2 Home Page"
[installation]:    http://www.cs.utexas.edu/users/moore/acl2/current/HTML/installation/installation.html
[releases]:        https://github.com/acl2-devel/acl2-devel/releases/
[git]:             http://git-scm.com
[community books]: https://www.acl2.org/doc/index.html?topic=ACL2____COMMUNITY-BOOKS

#### Development Version

To check out the latest development version of the repository using
`git`, you can (for example) do the following in a fresh directory
(note the "." at the end):

```
git clone https://github.com/acl2/acl2 .
```

### Contributing

See the documentation for [how to contribute][how-to-contribute].

[how-to-contribute]: https://www.acl2.org/doc/index.html?topic=ACL2____HOW-TO-CONTRIBUTE

### Staying Informed

We encourage users of ACL2 to join our [mailing lists][mailing-lists]
and take advantage of other [ACL2 Community resources][community].

[mailing-lists]: https://www.acl2.org/doc/index.html?topic=ACL2____MAILING-LISTS
[community]: https://www.acl2.org/doc/index.html?topic=ACL2____COMMUNITY

### Contributors Wanted!

Everyone can contribute documentation and advice to our [wiki] and
discuss [problems and feature requests][bugtracker].

If you would like to contribute to this repository, see the
documentation topic [git-quick-start].  Please note the [guidelines for
book development][books guidelines].

[git-quick-start]:  https://www.acl2.org/doc/index.html?topic=ACL2____GIT-QUICK-START
[wiki]:             https://github.com/acl2/acl2/wiki
[bugtracker]:       https://github.com/acl2/acl2/issues
[books guidelines]: https://www.acl2.org/doc/index.html?topic=ACL2____BEST-PRACTICES
