GAP (http://www.gap-system.org) is a system for computational discrete algebra, with particular emphasis on Computational Group Theory. GAP provides a programming language, a library of thousands of functions implementing algebraic algorithms written in the GAP language as well as large data libraries of algebraic objects.
GAP is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License; either version 2 of the License, or (at your option) any later version. For details, see the file 'GPL' in the 'etc' directory of the GAP distribution.