;::vertex_descriptor 
    s = vertex(SanJose, G);

  cout &lt;&lt; &quot;*** Breadth First ***&quot; &lt;&lt; endl;
  breadth_first_search(G, s, city_visitor(names), colors.begin());

  return 0;
}
</PRE>

<P>

<H2><A NAME="sec:custom-exterior-property-maps"></A>
Constructing an Exterior Property Map
</H2>

<P>
Implementing your own exterior property maps is not very
difficult. You simply need to overload the functions required by the
<a href="property_map.html">property map concept</a>
that you want your c