## &gpd;

Groupoids, graphs of groups, and graphs of groupoids
Version 1.03
Emma Moore emmajmoore@yahoo.co.uk
Chris Wensley c.d.wensley@bangor.ac.uk http://www.informatics.bangor.ac.uk/~cwensley/

             School of Computer Science, Bangor University,

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

October 2007

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 1.03, released on October 8th 2007.

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

&copyright; 2000-2007 by Emma Moore and Chris Wensley

We adopt the copyright regulations of &GAP; as detailed in the copyright notice in the &GAP; manual.
<#Include SYSTEM "intro.xml"> <#Include SYSTEM "gpd.xml"> <#Include SYSTEM "gpdmor.xml"> <#Include SYSTEM "ggraph.xml"> <#Include SYSTEM "history.xml">