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<TitlePage>
<Title>
groupoids
</Title>
<Subtitle>
Calculations with finite groupoids and their homomorphisms
</Subtitle>
<
Version>
1.
79
</
Version>
<Author>
Emma J. Moore<Alt Only=
"LaTeX"><Br/></Alt>
</Author>
<Author>
Chris Wensley<Alt Only=
"LaTeX"><Br/></Alt>
<Email>cdwensley.maths@btinternet.com</Email>
<Homepage>
https://github.com/cdwensley</Homepage>
</Author>
<Date>
11 September
2025
</Date>
<Abstract>
The &groupoids; package provides functions for computation with groupoids (categories with every arrow i
nvertible) and their morphisms; for graphs of groups, and graphs of groupoids.
The most basic structure introduced is that of <E>magma with objects</E>; followed by <E>semigroup with objects</E>; then <E>monoid with objects</E>; and finally <E>groupoid</E>, which is a <E>group with objects</E>.
<P/>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. <P/>The &groupoids; package was originally implemented in 2000 (as <Package>GraphGpd</Package>) when the first author was studying for a Ph.D. in Bangor.
<P/>The package was then renamed <Package>Gpd</Package> and version 1.07 was released in July 2011, ready for &GAP; 4.5.
<P/><Package>Gpd</Package> became an accepted &GAP; package in May 2015.
<P/>In April 2017 the package was renamed again, as <Package>groupoids</Package>.
<P/>Later versions implement many of the constructions described in the paper <Cite Key='AlWe' /> for automorphisms of groupoids.
<P/>Bug reports, comments, suggestions for additional features, and offers to implement some of these, will all be very welcome.
<P/>Please submit any issues at <URL>https://github.com/gap-packages/groupoids/issues/</URL> or send an email to the second author at <Email>cdwensley.maths@btinternet.com</Email>.
<P/>
</Abstract>
<Copyright>
© 2000-2025, Emma Moore and Chris Wensley.<P/>
The &groupoids; 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>
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