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<Title>Vertex Mutable Graph</Title>
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<H2><A NAME="concept:VertexMutableGraph">
Vertex Mutable Graph
</H2>

A vertex mutable graph can be changed by adding or removing
vertices. The memory management is the responsibility of the graph
implementation. The graph user need only make calls to
<TT>add_vertex</TT> and <TT>remove_vertex</TT> and the graph
implementation does the rest.

<H3>Refinement of</H3>

<a href="./Graph.html">Graph</a> and <a
href="http://www.sgi.com/tech/stl/DefaultConstructible.html">DefaultConstructible</a>

<H3>Associated Types</H3>

No additional associated types.

<h3>Valid Expressions</h3>

<ul>
<li><a name="sec:add_vertex"><TT>add_vertex(g)</TT></a> 
<b>returns</b> <TT>vertex_descriptor</TT>
<br><br>

<b>Semantics:</b>  Add a new vertex to the graph. The
        <TT>vertex_descriptor</TT> for the new vertex is returned.<br>
</li>

<li><a name="sec:remove_vertex"><tt>remove_vertex(u, g)</tt></a>
<b>returns</b> <tt>void</tt><br><br>

<b> Semantics:</b>  Remove <i>u</i> from the vertex set of the graph.
<br>
<b> Preconditions:</b> <i>u</i> is a valid vertex descriptor of graph <i>g</i>
     and there are no edges incident to vertex <i>u</i>. The function
     <TT>clear_vertex</TT> can be used to remove all incident edges.
<br>
<b> Postconditions: </b> <TT>num_vertices(g)</TT> is one less; <i>u</i>
      no longer appears in the vertex set of the graph and it
      is no longer a valid vertex descriptor. 
</li>

</ul>

<H3>Complexity guarantees</H3>
<ul>
  <li> Vertex insertion is guaranteed to be amortized constant time.
 
  <li> Vertex removal is at most <TT>O(|E| + |V|)</TT>.
</ul>


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<TABLE>
<TR valign=top>
<TD nowrap>Copyright &copy; 2000-2001</TD><TD>
<A HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</A>, Indiana University (<A HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)
<A HREF="http://www.boost.org/people/jeremy_siek.htm">Lie-Quan Lee</A>, Indiana University (<A HREF="mailto:llee@cs.indiana.edu">llee@cs.indiana.edu</A>)
</TD></TR></TABLE>

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