[GRASSLIST:5185] Converting polygon maps to graphs

[swlab]

Hello,
I have a vector map of polygons, and I'd like to transform it as a graph (ie, 
each polygon centroid would be a node, 2 nodes would be connected if the 
polygons they represent share a common boundary...)
Is there any simple way to do it with GRASS57 ? If not, could anybody point me 
to some online resources ? I'm sure that some algorithms exist already, but 
I've no idea on how to find them. I'm quite willing to work with shapelibs if 
needed, but then again, I don't really know where to start.

Thanks a lot for any idea

Cheers
P.
-- 
Soil and Water Laboratory
Dept. of Biological and Environmental Engineering
Cornell University
Riley Robb Hall
ITHACA, NY 14853