gt;::adjacency_iterator
</pre>
    The type for the iterators returned by <tt>adjacent_vertices</tt>. 
    (Required by <a href="AdjacencyGraph.html">AdjacencyGraph</a>.)

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<pre>
graph_traits&lt;subgraph&gt;::directed_category
</pre>
    Provides information about whether the graph is directed
    (<tt>directed_tag</tt>) or undirected (<tt>undirected_tag</tt>).
    (Required by <a href="Graph.html">Graph</a>.)

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<pre>
graph_traits&lt;subgraph&gt;::edge_parallel_category
</pre>
    This describes whe