ry</tt>
<br><br>
  Provides information about whether the graph is directed
  (<tt>directed_tag</tt>) or undirected (<tt>undirected_tag</tt>).<br>
  (Required by <a href="Graph.html">Graph</a>.)

<hr>
<tt>graph_traits&lt;adjacency_matrix&gt;::edge_parallel_category</tt>
<br><br>
  An adjacency matrix does not allow the insertion of
  parallel edges, so this type is always
  <tt>disallow_parallel_edge_tag</tt>. <br>
  (Required by <a href="Graph.html">Graph</a>.)

<hr>
<tt>graph_traits&lt;adjacency_matrix&gt