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<!--  manual.xml         IdRel documentation              Chris Wensley  -->
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<!--  Copyright (C) 1999-2018, Anne Heyworth and Chris Wensley,          --> 
<!--  School of Computer Science, Bangor University, U.K.                --> 
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<?xml version="1.0" encoding="UTF-8"?>

<!-- Reading data chunk from the PackageInfo.g file --> 

<!DOCTYPE Book SYSTEM "gapdoc.dtd"
  [<!ENTITY idrel "<Package>IdRel</Package>"> 
   <#Include Label="PKGVERSIONDATA"> 
  ]> 

<!-- The documentation to the IdRel package. -->

<Book Name="IdRel"> 

<TitlePage>
  <Title>&idrel;</Title>
  <Subtitle>A package for Identities among Relators</Subtitle>
  <Version>Version &IDRELVERSION;</Version>   
  <Date>&IDRELRELEASEDATE;</Date> 
  <Author> Anne Heyworth </Author>    
  <Author> Chris Wensley
    <Email>c.d.wensley@bangor.ac.uk</Email>
    <Homepage>http://pages.bangor.ac.uk/~mas023/</Homepage>
      <Address> 
        School of Computer Science, Bangor University,<Br/> 
        Dean Street, Bangor, Gwynedd, LL57 1UT, U.K. 
      </Address> 
  </Author>

<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/>
&idrel; became an accepted &GAP; package in May 2015. 
<P/>
Bug reports, suggestions and comments are, of course, welcome. 
Please submit an issue at 
<URL>https://github.com/gap-packages/idrel/issues/</URL>
or send an email to the second author at 
<Email>c.d.wensley@bangor.ac.uk</Email>.
</Abstract>

<Copyright> 
<Index>License</Index>
&copyright; &IDRELCOPYRIGHTYEARS; Anne Heyworth and Chris Wensley <P/>

&idrel; is free software; you can redistribute it 
and/or modify it under the terms of the 
<URL Text="GNU General Public License">http://www.fsf.org/licenses/gpl.html</URL> 
as published by the Free Software Foundation; 
either version 2 of the License, or (at your option) any later version.
</Copyright>

<Acknowledgements>
This documentation was prepared with the <Package>GAPDoc</Package> 
package <Cite Key="GAPDoc" /> of Frank L&#xfc;beck and Max Neunh&#xf6;ffer. 
<P/> 
The procedure used to mount new releases on GitHub uses the packages 
<Package>GitHubPagesForGAP</Package> 
<Cite Key="GitHubPagesForGAP" /> 
and <Package>ReleaseTools</Package> of Max Horn. 
</Acknowledgements>

</TitlePage>

<TableOfContents/>

<Body>

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

</Body>

<Bibliography Databases="bib.xml"/>
<!--  <Bibliography Databases="manual"/> --> 

<TheIndex/>

</Book>
