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<Title>Challenge</Title>
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<h2>Boost Graph Library Challenge and To-Do Items</h2>


<ul>

<li>Dynamic graph algorithms such as described in <a
href="http://citeseer.ist.psu.edu/eppstein99dynamic.html">Dynamic Graph
Algorithms</a> and <a
href="http://citeseer.ist.psu.edu/alberts98software.html">A Software
Library of Dynamic Graph Algorithms</a>.

<li>Polish up code/docs for pending items and champion the formal
review. The pending items are:</li>
  <ul>
   <li><tt>container_traits.hpp</tt> (this should also include
     the work Matt Austern is doing on this topic)</li>

   <li>The queues and heaps: <tt>queue.hpp</tt>,
     <tt>mutable_queue.hpp</tt>, <tt>fibonacci_heap.hpp</tt>.
      Somehow merge implementation with Dietmer's heaps and queues.</li>

   <li><tt>disjoint_sets</tt> </li>
  </ul>

<li>Construct a set of planar graph algorithms.</li>
  <ul>
   <li> Is the graph planar?</li>
   <li> &quot;Walk around the block&quot; and similar open and closed neighborhood 
traversals. Note that edge traversals need to resolve to particular ends 
and sides (see below), not just to the edge as a whole.</li>
   <li> Given a point, find the nearest vertex, edge, or bounded polygon. 
Again, edges are viewed as having left and right sides.</li>
   <li> Given a line segment, find intersecting vertices, edges, or bounded 
polygons.</li>
   <li> Given a polygon, find intersecting whatever...</li>
   <li> Various minimum bounding rectangle and clipping problems.</li>
   <li> Construct a planar embedding of a planar graph.</li>
   <li> Find a balanced separator of a graph.</li>
   <li> Modify adjacency_list so that the out-edges can be ordered
    according to a user defined comparison object.</li>
  </ul>

<li>Rewrite the Qhull algorithm using the Boost Graph Library (this is
high difficulty challenge).  Or, for a more manageable challenge,
write an interface for Qhull with the BGL.  <a
href="http://www.geom.umn.edu/locate/qhull">Qhull</a> computes the
convex hull, Delaunay triangulation, Voronoi diagram, and halfspace
intersection about a point.  Qhull runs in 2-d, 3-d, 4-d, and higher
dimensions.  Qhull is used for collision detection, animation, plate
tectonics, 3-d modeling, robot motion planning, and other <a
href="http://www.geom.umn.edu/~bradb/qhull-news.html#use">applications</a>.
It is currently difficult to use from a C++ program.

</li>


<li>Explore the use of Algorithm Objects as an alternative to
  the current approach with visitors.</li>

<li>Analyze the algorithms that do not yet have visitors, and
  come up with visitor interfaces for them.</li>

<li>Add a check in the adjacency_list class to make sure
  all the vertex property template arguments have kind=vertex_property_tag
  and all edge property template arguments have kind=edge_property_tag.</li>

<li>Clean up the output functions in graph_utility.hpp to
  use streams, and document all the utility functions. Replace
  the random number stuff with calls to the boost random number generator.</li>

<li>Modularize the tests in test/graph.cpp to apply to particular
  concepts. Make sure there are run-time tests for every BGL concept.</li>

<li>Write tests for the BGL algorithms. There are a few, but
   more are needed. The example provide a sanity check but do not
   provide full coverage.</li>

<li>Write up the examples from Knuth's <i>Stanford GraphBase</i> using
  the BGL. The file <a
  href="../example/miles_span.cpp"><tt>examples/miles_span.cpp</tt></a>
  is a start.</li>

<li>Further testing of the <tt>subgraph</tt> class and add more
   features.</li>

<li>Implement a minimum-cost maximum-flow algorithm.</li>

<li>Make the <tt>type</tt> of all (internal) property maps convertible to the <tt>const_type</tt> of the property maps.<li>

<li>Add static functions to <tt>adjacency_list</tt> to return the per-vertex, per-edge, and per-graph overhead.</li>
</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>)
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