[computer-go] Voronoi diagram revisited

[Jason House]

Hideki Kato wrote:
> ++++++
> +X+ at ++
> OXO+++
> OOXX++
> +OO+++
> 
> Corresponding Voronoi diagram with Manhattan distance is (+ is neutral point):
> 
> XXX+O+
> +X+O+X
> OXO+XX
> OOXXXX
> OOO+XX

I think that last diagram was not generated with manhattan distances, 
but instead euclidean distances.  I believe the following would be the 
correct diagram for manhattan distances:

+X++++
+X++++
OXO+++
OOXXXX
OOO+++