Properties of the adjacency matrix.

[brandimarte]

After applying the reverse Cuthill-McKee band-width reduction algorithm to the adjacency matrix representing the connectivity of carbon sp2 structures in examples folder one note a very particular structure. So the following questions arise:

1. Is it always going to happen for any sp2 structure?
2. If answer of '1' is 'yes', then are there general rules that those matrix obey?
3. If answer of '2' is 'yes', what are the rules?
4. If able to answer '3', how can we profit from those properties to our problem?