Thanks very much to all for your replies! I appreciate you taking the time.

Initially, I searched CPAN for "breadth first" and came up with Graph::BFS (it's at the top of the results ;) ), but until djantzen's suggestions about Graph::Traversal and adjaceny matrices, I could not see how to make it go...

While I certainly agree with jkhan about the Graph modules' documentation, the dots are now connected and I have learned a great deal.

Now, to go get a copy of Mastering Algorithms with Perl!