## &idrel;

A package for Identities among Relators
Version 2.03
Anne Heyworth anne.heyworth@googlemail.com
Chris Wensley c.d.wensley@bangor.ac.uk http://www.informatics.bangor.ac.uk/~cwensley/

          School of Computer Science, Bangor University,

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

October 2007

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 relations 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; 2005-2007 by Anne Heyworth and Chris Wensley

We adopt the copyright regulations of &GAP; as detailed in the copyright notice in the &GAP; manual.
<#Include SYSTEM "intro.xml"> <#Include SYSTEM "rws.xml"> <#Include SYSTEM "logrws.xml"> <#Include SYSTEM "monpoly.xml"> <#Include SYSTEM "modpoly.xml">