## &idrel;

A package for Identities among Relators
Version 2.05
Anne Heyworth anne.heyworth@googlemail.com
Chris Wensley c.d.wensley@bangor.ac.uk http://www.bangor.ac.uk/~mas023/

          School of Computer Science, Bangor University,

          Dean Street, Bangor, Gwynedd, LL57 1UT, U.K.

November 2008

The &idrel; package was originally implemented in 1999, using the &GAP; 3 language, when the first author was studying for a Ph.D. in Bangor.

This package is designed to compute a minimal set of generators for the module of the identities among relators of a group presentation. It does this using rewriting and logged rewriting: a self-contained implementation of the Knuth-Bendix process using the monoid presentation associated to the group presentation; monoid polynomials: an implementation of the monoid ring; module polynomials: an implementation of the right module over this monoid generated by the relators. Y-sequences: used as a rewriting way of representing elements of a free crossed module (products of conjugates of group relators and inverse relators).

Bug reports, suggestions and comments are, of course, welcome. Please contact the second author at c.d.wensley@bangor.ac.uk.

&copyright; 2005-2008 Anne Heyworth and Chris Wensley

This `idrel` package is released under the GNU General Public License (GPL). This file is part of `idrel`, though as documentation it is released under the GNU Free Documentation License (see http://www.gnu.org/licenses/licenses.html#FDL).

idrel
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.

idrel
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.

You should have received a copy of the GNU General Public License along with `idrel`; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

For more details, see http://www.fsf.org/licenses/gpl.html.

This documentation was prepared with the `GAPDoc` package of Frank L\"ubeck and Max Neunh\"offer.
<#Include SYSTEM "intro.xml"> <#Include SYSTEM "rws.xml"> <#Include SYSTEM "logrws.xml"> <#Include SYSTEM "monpoly.xml"> <#Include SYSTEM "modpoly.xml">