## &gpd;

Groupoids, graphs of groups, and graphs of groupoids
Version 1.05
Emma Moore emmajmoore@yahoo.co.uk
Chris Wensley c.d.wensley@bangor.ac.uk http://www.bangor.ac.uk/~mas023/

             School of Computer Science, Bangor University,

          Dean Street, Bangor, Gwynedd, LL57 1UT, U.K.

November 2008

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.

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.

The &gpd; package was originally implemented in 2000 (as `GraphGpd`) when the first author was studying for a Ph.D. in Bangor.

The current version is 1.05, released on 21st November 2008, and now includes the more basic structure of magma with objects. It had to be released hurriedly, due to the change of website, so some of the function are no longer available. A new version will be released as soon as possible.

Bug reports, suggestions and comments are, of course, welcome. Please contact the second author at c.d.wensley@bangor.ac.uk.

&copyright; 2000-2008 Emma Moore and Chris Wensley

This `gpd` package is released under the GNU General Public License (GPL). This file is part of `gpd`, though as documentation it is released under the GNU Free Documentation License (see http://www.gnu.org/licenses/licenses.html#FDL).

gpd
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.

gpd
is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with `gpd`; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

For more details, see http://www.fsf.org/licenses/gpl.html.

This documentation was prepared with the `GAPDoc` package of Frank L\"ubeck and Max Neunh\"offer.
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