[Computer-go] Computing CFG distance in practice

[Jacques Basaldúa]

Hi,

I got a lot of improvement recently (something you all
did long time ago) with proximity heuristics. I am using

Manhattan distance:
   d = max(dx, dy)

and
   d = max(dx, dy) + (dx + dy)/2

where dx = abs(ex - ox) and dy = abs(ey - oy)

But many people report CFG distance to be superior.

What do you do:

a. Compute it in root. Then build a lookup table and
use the LUT during playouts and tree search.

b. Compute the shortest path from (ox, oy) to (ex, ey)
connected by the stones on the board each time you need
to evaluate a distance.

I don't like a because it looks inefficient as the
board changes a lot during the search.

I don't like b because it looks computing intense
unless there is some smart idea I am missing.


Jacques.