<?xml version="1.0" encoding="ISO-8859-1"?>
  <!-- $Id: basics.xml,v 0.997  Exp $ -->
  <Chapter>
    <Heading>
      Introduction
    </Heading>

The aim of this package is to turn 
<Package> GAP </Package> more user-friendly, at least for semigroup theorists.
It requires the usage of external programs as is the case of 
<C>graphviz</C> <Cite Key="KoutsofiosNorth:2002"/>, a software for drawing graphs developed at AT
    <Alt Only="LaTeX">
      \&#38;
    </Alt>
    <Alt Not="LaTeX">
      <Alt Only="HTML">
        &#38;amp;
      </Alt>
      <Alt Not="HTML">
        &#38;
      </Alt>
    </Alt>
    T Labs, that can be obtained at
    <URL>http://www.graphviz.org/</URL>.
It is used not only to draw right Cayley graphs of finite semigroups and Sch{\"u}zenberger graphs of finite inverse semigroups but also to visualize in the usual way the egg-box picture of a D-classe of a finite semigroup. 

<Alt Only="LaTeX">
\ \\
\ \\
    </Alt>
<Alt Only="HTML">
&lt;br&gt;&lt;br&gt;
</Alt>
<B>Important note</B>: The version of <C>graphviz</C> to install should be
greater or equal to 1.16.
<Alt Only="LaTeX">
\ \\
\ \\
    </Alt>
<Alt Only="HTML">
&lt;br&gt;&lt;br&gt;
</Alt>

Tcl/Tk should also be available in order to run the graphical interfaces
(XAutomaton and XSemigroup)
used to specify automata and semigroups.

  </Chapter>
