I worked on a vaguely similar problem--nodes-path-ish--and
we ended up making a tree of paths, sorting it depthwise and
breadthwise and then finding an optimized path. You may want
to consider looking at the discrete computing stuff, things
isomorphisms and node graphing. There's a red book with white
webs all over the cover, who's author I can't remember. The
title is something like -Discrete Algorithms-; it was pretty
helpful.
-B.