GAP (Groups, Algorithms and Programs) is a free system for computational discrete algebra. Its capabilities include computation involving cyclotomic and finite fields, residue class rings, p-adic numbers, multivariate polynomials and rational functions, vectors, matrices and finite groups. GAP can be copied and distributed freely for any non-commercial purpose. If you use GAP in your research papers, please inform gap@dcs.st-and.ac.uk and cite GAP in your publication. Please see http://www.gap-system.org/Bib/cite.html for more details.