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<!--  intro.xml             KAN documentation             Chris Wensley  -->
<!--                                                    & Anne Heyworth  -->
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<!--  $Id: intro.xml,v 0.94 2006/06/02 gap Exp $                         -->
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  <!-- <M>Id: intro.xml,v 0.92  Exp <M> -->

<Chapter Label="intro">
<Heading>Introduction</Heading>

The &kan; package started out as part of Anne Heyworth's thesis 
<Cite Key="anne-thesis" />}, and was designed to compute 
induced actions of categories (see also <Cite Key="BrHe" />). 
<P/>
This version of &kan; only provides functions for the computation of
normal forms of representatives of double cosets of finitely presented groups, 
and is made available in support of the paper <Cite Key="BrGhHeWe" />. 
Existing methods for computing double cosets in &GAP; are described 
in <Cite Key="SteveL" />.
<P/>
The package is loaded into &GAP; with the command
<Example>
<![CDATA[
gap> LoadPackage( "kan" ); 
]]>
</Example>

This version of &kan; has been prepared for &GAP;~4.4.6. 
Some of the functions in the <Package>automata</Package> share package 
are used to compute word acceptors and regular expressions 
for the languages they accept.
<P/>
The <Package>kbmag</Package> share package is also used 
to compute a word acceptor of a group <C>G</C> 
when <C>G</C> has no finite rewriting system. 
If <Package>kbmag</Package> is not available 
(the user is not on a UNIX system, or the C-programs have not been compiled), 
the file <File>dckbmag.gi</File> will not be read, 
so methods for the functions detailed in section 2.4.1 will not be available.
<P/>
The information parameter <C>InfoKan</C> takes default value <C>0</C>.
When raised to a higher value, additional information is printed out.
<P/>
The following test file (assuming the user is in the <C>kan</C> directory) 
runs all the manual examples.

<Example>
<![CDATA[
gap> ReadTest("tst/kan_manual.tst");
+ setting AssertionLevel to 0 to avoid recursion in Automata
+ Testing all example commands in the Kan manual
+ GAP4stones: 6
true
]]>
</Example>
(If <Package>kbmag</Package> is not loaded then a collection of 
error lines for Example 3 will be printed out.)
<P/>
Please send bug reports, suggestions and other comments to the second author.
<P/>
The &kan; package is subject to the &GAP; copyright regulations as 
detailed in the copyright notice in the &GAP; manual.

</Chapter>
