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<!--  manual.xml            XMod documentation            Chris Wensley  -->
<!--                                                        & Murat Alp  -->
<!--  version 2.32, 12/01/2015                                           --> 
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<!--  Copyright (C) 2001-2015, Murat Alp and Chris Wensley,              --> 
<!--  School of Computer Science, Bangor University, U.K.                --> 
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<!-- The documentation to the XMod package. -->

<Book Name="XMod"> 

<TitlePage>
  <Title>&XMod;</Title>
  <Subtitle>Crossed modules and cat1-groups in &GAP;</Subtitle>
  <Version>Version &VERSION;</Version>
  <Date>&RELEASEDATE;</Date> 
  <Author> Murat Alp
    <Email>muratalp@nigde.edu.tr</Email>
    <Address>
      Nigde &#xdc;niversitesi,<Br/> 
      Fen Edebiyat Fak&#xfc;ltesi, Matematik B&#xf6;l&#xfc;m&#xfc;<Br/>
      Nigde, Turkey.
    </Address>
  </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 &xmod; package provides functions for computation with 
<List> 
<Item>
finite crossed modules of groups and cat1-groups, 
and morphisms of these structures;
</Item>
<Item>
finite pre-crossed modules, pre-cat1-groups, and their Peiffer quotients;
</Item>
<Item>
derivations of crossed modules and sections of cat1-groups; 
</Item>
<Item>
the actor crossed square of a crossed module. 
</Item>
</List> 
Initial, experimental versions of the following are also included 
in this version: 
<List>
<Item>
crossed squares and their morphisms; 
</Item>
<Item>
crossed modules of groupoids. 
</Item>
</List>
<P/>
&xmod; was originally implemented in 1997 using the &GAP;3 language.
when the first author was studying for a Ph.D. <Cite Key="A1"/> in Bangor.
<P/>
In April 2002 the first and third parts were converted to &GAP;4, 
the pre-structures were added, and version 2.001 was released. 
The final two parts, covering derivations, sections and actors, 
were included in the January 2004 release 2.002 for &GAP; 4.4.
<P/>
Version 2.19 was released on 9th June 2012 for the first release of 
&GAP; 4.5. 
<P/>
The current version is &VERSION;, released &LONGRELEASEDATE; for &GAP; 4.7. 
<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> 
<Index>License</Index>
&copyright; &COPYRIGHTYEARS; Murat Alp and Chris Wensley.  

&xmod; 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 of Frank L&#xfc;beck and Max Neunh&#xf6;ffer. 
<P/>
The first author wishes to acknowledge support from 
Dumlupinar University and the Turkish government. 
</Acknowledgements>

</TitlePage>

<TableOfContents/>

<Body>

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