Crossed Modules and Cat1-Groups

Version 2.77
Released 2019-11-17

This project is maintained by Chris Wensley

Build Status Code Coverage

The GAP 4 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.

In October 2015 a new section on isoclinism of crossed modules was added.

Experimental functions for crossed squares and cat2-groups are now included.


The ‘XMod’ package is Copyright {\copyright} Chris Wensley et al, 1997–2017.

‘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 http://www.gnu.org/licenses/gpl.html



If you have a question relating to ‘XMod’, encounter any problems, or have a suggestion for extending the package in any way, please