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<!--  manual.xml         IdRel documentation              Chris Wensley  -->
<!--                                                    & Anne Heyworth  -->
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<!--  $Id: manual.xml,v 2.05 2008/11/21 gap Exp $                        -->
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  <!-- $Id: manual.xml,v 2.05  Exp $ -->

<!DOCTYPE Book SYSTEM "gapdoc.dtd"
[<!ENTITY idrel "<Package>IdRel</Package>">] >

<Book Name="IdRel"> 

<TitlePage>
  <Title>&idrel;</Title>
  <Subtitle>A package for Identities among Relators</Subtitle>
  <Version>Version 2.05</Version>

  <Author> Anne Heyworth
    <Email>anne.heyworth@googlemail.com</Email>
  </Author>    
  <Author> Chris Wensley
    <Email>c.d.wensley@bangor.ac.uk</Email>
    <Homepage>http://www.bangor.ac.uk/~mas023/</Homepage>
    <Address>
      School of Computer Science, Bangor University,<Br/>
      Dean Street, Bangor, Gwynedd, LL57 1UT, U.K.
    </Address>
  </Author>

  <Date>November 2008</Date>

<Abstract>
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.
<P/>
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
<List>
<Item>
rewriting and logged rewriting: a self-contained implementation
of the Knuth-Bendix process using the monoid presentation
associated to the group presentation;
</Item>
<Item>
monoid polynomials: an implementation of the monoid ring;
</Item>
<Item>
module polynomials: an implementation of the right module
over this monoid generated by the relators.
</Item>
<Item>
Y-sequences: used as a <E>rewriting</E> way of representing
elements of a free crossed module
(products of conjugates of group relators and inverse relators).
</Item>
</List>
<P/>
Bug reports, suggestions and comments are, of course, welcome. 
Please contact the second author at     
<Email>c.d.wensley@bangor.ac.uk</Email>.
</Abstract>

<Copyright> 
&copyright; 2005-2008 Anne Heyworth and Chris Wensley <P/>
</Copyright>

<Acknowledgements>
This <Package>idrel</Package> package is released under the 
GNU General Public License (GPL).
This file is part of <Package>idrel</Package>, though as documentation
it is released under the
GNU Free Documentation License
(see <URL>http://www.gnu.org/licenses/licenses.html#FDL</URL>).
<P/>
<Package>idrel</Package> 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.
<P/>
<Package>idrel</Package> 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.
<P/>
You should have received a copy of the GNU General Public License
along with <Package>idrel</Package>; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA. 
<P/>
For more details, see 
<URL>http://www.fsf.org/licenses/gpl.html</URL>. 
<P/>
This documentation was prepared with the <Package>GAPDoc</Package> 
package of Frank L\"ubeck and Max Neunh\"offer. 
</Acknowledgements>
</TitlePage>

<TableOfContents/>

<Body>

<#Include SYSTEM "intro.xml">
<#Include SYSTEM "rws.xml">
<#Include SYSTEM "logrws.xml">
<#Include SYSTEM "monpoly.xml">
<#Include SYSTEM "modpoly.xml">

</Body>

<Bibliography Databases="manual"/>

<TheIndex/>

</Book>
