<!-- ------------------------------------------------------------------- --> <!-- --> <!-- history.xml Gpd documentation Chris Wensley --> <!-- & Emma Moore --> <!-- --> <!-- $Id: history.xml,v 1.05 2008/11/21 gap Exp $ --> <!-- --> <!-- ------------------------------------------------------------------- --> <?xml version="1.0" encoding="ISO-8859-1"?> <!-- $Id: history.xml,v 1.05 Exp $ --> <Chapter Label="history"> <Heading>Development History</Heading> <Section><Heading>Versions of the Package</Heading> The first version, <Package>GraphGpd</Package> 1.001, formed part of Emma Moore's thesis <Cite Key="emma-thesis" /> in December 2000, but was not made generally available. <P/> Version 1.002 of <Package>GraphGpd</Package> was prepared to run under &GAP; 4.4 in January 2004; was submitted to the &GAP; council to be considered as an accepted package; but suggestions from the referee were not followed up. <P/> In April 2006 the manual was converted to <Package>GAPDoc</Package> format. Variables <C>Star</C>, <C>Costar</C> and <C>CoveringGroup</C> were found to conflict with usage in other packages, and were renamed <C>VertexStar</C>, <C>VertexCostar</C> and <C>CoveringGroupOfGroupoid</C> respectively. Similarly, the <C>Vertices</C> and <C>Arcs</C> of an <C>FpWeightedDigraph</C> were changed from attributes to record components. <P/> In the spring of 2006 the package was extensively rewritten and renamed &gpd;. Version 1.01 was submitted as a deposited package in June 2006. Version 1.03, of October 2007, fixed some file protections, and introduced the test file <F>gpd_manual.tst</F>. <P/> Version 1.05, of November 2008, was released because the website at Bangor changed. <P/> <E>A further extensive rewrite is in progress, introducing magmas with objects and their mappings, but many of the functions fail to work at present, and this manual is far from correct.</E> </Section> <Section><Heading>What needs to be done next?</Heading> Computationally, there are three types of connected groupoid: <List> <Item> those with identical object groups, </Item> <Item> those with object groups conjugate in some supergroup, </Item> <Item> those with object groups which are simply isomorphic. </Item> </List> <Package>GraphGpd</Package> attempted to implement the second case, while &gpd; 1.01 and 1.03 considered only the first case, and &gpd; 1.05 extended 1.03 to the second case. Here are some other immediate requirements: <List> <Item> Automorphism group of a groupoid. </Item> <Item> normal subgroupoids and quotient groupoids; </Item> <Item> more methods for morphisms of groupoids, particularly when the range is not connected; </Item> <Item> <C>ImageElm</C> and <C>ImagesSource</C> for the cases of groupoid morphisms not yet covered; </Item> <Item> <C>Enumerator</C> for <C>IsHomsetCosetsRep</C>; </Item> <Item> free groupoid on a graph; </Item> <Item> methods for <C>FreeProductWithAmalgamation</C> and <C>HnnEntension</C> for pc-groups; </Item> <Item> convert <C>GraphOfGroupsRewritingSystem</C> to the category <C>IsRewritingSystem</C>; </Item> <Item> in <Package>XMod</Package>, implement crossed modules over groupoids. </Item> </List> </Section> </Chapter>