Language: GAP 4.5
Operating System: Any
Latest version: 1.14 (23/04/2012)
Current archive: gpd-1.14.tar.gz
README file: README
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The Gpd package provides functions for computation with finite groupoids and their morphisms.
The first part is concerned with the standard constructions for
connected groupoids, and for groupoids with more than one component.
Groupoid morphisms are also implemented, and an experimental version of the automorphism group is included.
The second part implements graphs of groups and graphs of groupoids.
A graph of groups is a directed graph with a group at each vertex and with isomorphisms between subgroups on each arc.
This construction enables normal form computations for free products with amalgamation, and for HNN extensions, when the vertex groups come with their own rewriting systems.
For further information, see Emma Moore's Ph.D. thesis: moore.ps.gz
Computationally, there are three types of connected groupoid:
The major restucturing for Gpd 1.07 introduced magmas with objects, and built up from these through semigroups with objects and monoids with objects to groups with objects, which are groupoids.
The latest versions, prepared for GAP 4.5, include experimental methods for automorphism groups of groupoids, and implementation of homogeneous discrete groupoids which are needed by the XMod package for crossed modules over groupoids.
School of Computer Science
LL57 1UT, UK
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