Anton Sherwood wrote:

I'm using eigenvectors of a graph's adjacency matrix as "topological" coordinates of the graph's vertices as embedded in 3space (something I learned about just recently). Whenever I've done this with a graph that *does* have a good 3d embedding, using the first eigenvector results in a flat model: apparently the first is not independent, at least in such cases. . . .

Charles R Harris wrote:

. . . the embedding part sounds interesting, I'll have to think about why that works.

It's a mystery to me: I never did study enough matrix algebra to get a feel for eigenvectors (indeed this is the first time I've had anything to do with them). I'll happily share my code with anyone who wants to experiment with it. -- Anton Sherwood, http://www.ogre.nu/