e distance value type.<br>
  <b>Default:</b> <tt>std::plus&lt;DT&gt;</tt> with
   <tt>DT=typename&nbsp;property_traits&lt;WeightMap&gt;::value_type</tt>
</blockquote>

IN: <tt>distance_inf(DT inf)</tt> 
<blockquote>
  This value is used to initialize the distance for each
  vertex before the start of the algorithm. 
  The type <tt>DT</tt> must be the value type of the <tt>WeigthMap</tt>.<br>
  <b>Default:</b> <tt>std::numeric_limits::max()</tt>
</blockquote>

IN: <tt>distance_zero(DT zero)</tt> 
<blockquote