we see that vertices a-f are reachable from vertex a,
% but that verice g-i are not reachable.  Given the of the edges, this
% makes sense.

%%
% Let's look at breadth first search too, using a different example.
load_gaimc_graph('bfs_example');
figure(1); clf; graph_draw(A,xy,'labels',labels);

%%
% The breadth first search algorithm records the distance from the starting
% vertex to each vertex it visits in breadth first order.  This means it
% visits all the vertices in order of their distance from the s