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<!--  manual.xml             Gpd documentation            Chris Wensley  -->
<!--                                                       & Emma Moore  -->
<!--  Copyright (C) 2000-2016, Emma Moore 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 gpd "<Package>Gpd</Package>"> 
   <#Include Label="PKGVERSIONDATA"> 
  ]> 

<!-- The documentation for the Gpd package. -->

<Book Name="Gpd"> 

<TitlePage>
  <Title>&gpd;</Title>
  <Subtitle>Groupoids, graphs of groups, and graphs of groupoids</Subtitle>
  <Version>Version &GPDVERSION;</Version>   
  <Date>&GPDRELEASEDATE;</Date> 
  <Author> Emma Moore 
  </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 &gpd; package for &GAP;4 provides functions for 
the computation with groupoids (categories with every arrow invertible) 
and their morphisms; for graphs of groups, and graphs of groupoids. 
The most basic structure introduced is that of <E>magma with objects</E>, 
followed by <E>semigroup with objects</E>, then <E>monoid with objects</E> 
and finally <E>groupoid</E> which is a <E>group with objects</E>. 
<P/>
It provides normal forms for Free Products with Amalgamation 
and for HNN-extensions when the initial groups have rewrite systems 
and the subgroups have finite index.
<P/>
The &gpd; package was originally implemented in 2000 
(as <Package>GraphGpd</Package>) 
when the first author was studying for a Ph.D. in Bangor.
<P/>
Version 1.07 was released in July 2011, to be tested with &GAP; 4.5. 
Version 1.15 came out with the first release of &GAP; 4.5 in June 2012, 
and was submitted for official acceptance as a &GAP; package. 
<Package>Gpd</Package> became an accepted &GAP; package in May 2015. 
The latest version is &GPDVERSION; of &GPDLONGRELEASEDATE;, 
prepared for  &GAP; 4.8.  
<P/> 
Recent versions implement many of the constructions described in the paper 
<Cite Key="AlWe" /> for automorphisms of groupoids. 
<P/>
Bug reports, suggestions and comments are, of course, welcome. 
Please submit an issue at 
<URL>http://github.com/gap-packages/gpd/issues/</URL>
or send an email to the last author at 
<Email>c.d.wensley@bangor.ac.uk</Email>. 
</Abstract>

<Copyright> 
<Index>License</Index>
&copyright; &GPDCOPYRIGHTYEARS; Emma Moore and Chris Wensley <P/>

<Package>Gpd</Package> 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 "mwo.xml">
<#Include SYSTEM "mwohom.xml">
<#Include SYSTEM "gpd.xml">
<#Include SYSTEM "gpdhom.xml">
<#Include SYSTEM "ggraph.xml">
<#Include SYSTEM "tecnotes.xml">
<#Include SYSTEM "history.xml">

</Body>

<Bibliography Databases="bib.xml"/>

<TheIndex/>

</Book>
