tance_compare(CompareFunction cmp)</tt> 
<blockquote>
  This function is use to compare distances to determine
  which vertex is closer to the source vertex.
  The <tt>CompareFunction</tt> type must be a model of
  \stlconcept{BinaryPredicate} and have argument types that
  match the value type of the <tt>WeightMap</tt> property map.<br>
  <b>Default:</b> <tt>std::less&lt;DT&gt;</tt> with
  <tt>DT=typename&nbsp;property_traits&lt;WeightMap&gt;::value_type</tt>
</blockquote>

IN: <tt>distance_combine(Combine