Copyright and License

GAP is Copyright © 1987–2026 by its authors, who are listed in the file COPYRIGHT of the GAP distribution. Files in the distribution that carry a different copyright statement are excepted.

License

GAP is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The SPDX identifier for this is GPL-2.0-or-later.

GAP is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

The text of the license is in the file LICENSE of the GAP distribution and on the website of the Free Software Foundation.

Packages

The above covers GAP itself, not the 173 packages distributed with it. Each package is a separate work: its copyright is held by its authors or their institutions, and it has its own license, which need not be the license of GAP. Check the license of every package you use or redistribute.

Each distributed package states its license as an SPDX identifier in the License field of its PackageInfo.g file. The package list shows it in the details of each package.

Some packages include a copy of an external program or a data library that they provide an interface to. These have their own authors and may have their own terms; see the documentation of the package.

Third-party software

The GAP source distribution includes copies of the libraries GMP and zlib in the directory extern, each under its own license.

GAP uses GNU Readline if it is available when GAP is built. Readline is licensed under version 3 or later of the GNU General Public License, so a GAP executable linked with it may only be redistributed under version 3 or later, not under version 2.

GAP for Windows is built with Cygwin and linked with Readline, so the above applies to it. Its installer also contains a Cygwin environment with further third-party software, for example Git and Singular, each provided under its own license.

The GAP logo has separate terms, see The GAP Logo.

This website

The content of this website is Copyright © by its contributors; its source is at https://github.com/gap-system/GapWWW. Excepted are

  • third-party components such as MathJax, DataTables, the Ubuntu fonts and the Just the Docs theme, which have their own licenses;
  • the forum archive, whose messages belong to their authors.

Citing GAP

If you publish a result that was partly obtained using GAP, please cite it.