                       The XMOD package - version 2.41

This is the README file for the GAP package ``XMOD''.

This package allows for computation with crossed modules;
cat1-groups; morphisms of these structures; 
derivations of crossed modules and the corresponding sections of cat1-groups.
Experimental functions for crossed squares are now included.

Version 1 of ``XMOD'' was accepted for GAP3R4P4 in December 1996.
The first version for GAP4 was XMod 2.001, released in April 2002. 
The latest Version, 2.41, was released on 5th June 2015 for GAP 4.7. 
A more detailed history is included as Chapter 9 of the manual, 
with minor changes detailed in the file CHANGES.

The ``XMOD'' package is distributed with the accepted GAP packages.
It may also be obtained from the Bangor ftp pages for
Computational Higher-dimensional Discrete Algebra at: 
  http://pages.bangor.ac.uk/~mas023/chda/

The XMOD package is Copyright {\copyright} Chris Wensley and Murat Alp, 
1997--2015. 
XMOD 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. 
For details, see \URL{http://www.gnu.org/licenses/gpl.html}

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Installing `XMod':

1) unpack `xmod-2.41.tar.gz' in the `pkg' subdirectory of the GAP root
   directory.

2) From within GAP load the package with:

gap> LoadPackage("xmod");
true

3) The documentation is in the `doc' subdirectory.

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Contact:  c.d.wensley at bangor.ac.uk  to report problems, etc. 
