<?
xml version=
"1.0" encoding=
"UTF-8"?>
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<TitlePage>
<Title>
XMod
</Title>
<Subtitle>
Crossed Modules and Cat1-Groups
</Subtitle>
<
Version>
2.95
</
Version>
<Author>
Chris Wensley<Alt Only=
"LaTeX"><Br/></Alt>
<Email>cdwensley.maths@btinternet.com</Email>
<Homepage>
https://github.com/cdwensley</Homepage>
</Author>
<Author>
Murat Alp<Alt Only=
"LaTeX"><Br/></Alt>
<Address>
Prof. Dr. M. Alp<Br/>
Ömer Halisdemir University<Br/>
Art and Science Faculty<Br/>
Mathematics Department<Br/>
Nigde<Br/>
Turkey<Br/>
</Address>
<Email>muratalp@nigde.edu.tr</Email>
</Author>
<Author>
Alper Odabas<Alt Only=
"LaTeX"><Br/></Alt>
<Address>
Dr. A. Odabas <Br/>
Osmangazi University <Br/>
Arts and Sciences Faculty <Br/>
Department of Mathematics and Computer Science <Br/>
Eskisehir <Br/>
Turkey<Br/>
</Address>
<Email>aodabas@ogu.edu.tr</Email>
</Author>
<Author>
Enver Onder Uslu<Alt Only=
"LaTeX"><Br/></Alt>
</Author>
<Date>
10 July 2025
</Date>
<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>
isoclinism classes of groups and crossed modules;
</Item>
<Item>
derivations of crossed modules and sections of cat1-groups;
</Item>
<Item>
crossed squares and their morphisms, including the actor crossed square of a crossed module;
</Item>
<Item>
crossed modules of finite groupoids (experimental
version).
</Item>
</List>
<P/>
&XMod; was originally implemented in 1996 using the &GAP;3
language, when the second author was studying fo
r a Ph.D. <Cite Key='A1'/> in the School of Mathematics and Computer Science at Bangor University.
<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/>
In October 2015 functions for computing isoclinism classes of crossed modules, written by Alper Odabaş and Enver Uslu, were added.
These are contained in Chapter <Ref Chap='chap-isclnc' />, and are described in detail in the paper <Cite Key='IOU1' />.
<P/>
Bug reports, suggestions and comments are, of course, welcome. Please submit an issue at <URL>https://github.com/gap-packages/xmod/issues/</URL> or send an email to the first author at <Email>cdwensley@btinternet.com</Email>.
<P/>
</Abstract>
<Copyright>
© 1996-2025, Chris Wensley et al. <P/>
The &XMod; 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.
</Copyright>
<Acknowledgements>
This documentation was prepared using the &GAPDoc; <Cite Key='GAPDoc'/> and &AutoDoc; <Cite Key='AutoDoc'/> packages.<P/>
The procedure used to produce new releases uses the package <Package>GitHubPagesForGAP</Package> <Cite Key='GitHubPagesForGAP' /> and the package <Package>ReleaseTools</Package>.<P/>
</Acknowledgements>
</TitlePage>