riptor</TT>. Again we enforce
these requirements with concept checks. The return value of this
algorithm is the number of colors that were needed to color the graph,
hence the return type of the function is the graph's
<TT>vertices_size_type</TT>. The following code shows the interface for our
graph algorithm as a template function, the concept checks, and some
typedefs. The implementation is straightforward, the only step not
discussed above is the color initialization step, where we set the
color of all t