[computer-go] The dominance of search (Suzie v. GnuGo)

[compgo123 at aol.com]

I watched MoGo playing with different rank of players. Usually 5d players has no problem winning. Starting from 4d begin to lose games. However, part of it is due to most players are not familar with 9x9 Go. Taking this into consideration I place MoGo at about amateur 2d. For professional players consider 9x9 is solved. This is all my opinion.
 
Gnu plays at about 5k on 19x19. Let's place MoGo at 4k on 19x19. Besides the 32 times, it also need to make up the difference between 4k and 2d.
 
Exponential may not be the case. Just consider this that it could be factorial which is worse than expernential.
 
 
Daniel Liu    
 
-----Original Message-----
From: sylvain.gelly at m4x.org
To: computer-go at computer-go.org
Sent: Tue, 10 Apr 2007 3:12 PM
Subject: Re: [computer-go] The dominance of search (Suzie v. GnuGo)


Hello,


2007/4/6, Tom Cooper <main at astrolabe.plus.com>: 
My guess is that the complexity of achieving a fixed standard of play
(eg 1 dan) using a global alpha-beta or MC search is an exponential
function of the board size. 


(...)
To some extent, this is testable today by finding how a global search
program's strength scales with board size and with thinking
time

I have experiments of MoGo's playing strength against a fixed player (Gnugo 3.7.10 level 8) on different board sizes and different thinking times.
Of course, to meet your statement we have here to assume that the level of gnugo level 8 is a constant with the board size.

The results are that in order to keep the same winning rate, you have to increase the number of simulations by something a little larger than linear in the board area. From 9x9 to 13x13, you need something like 3 times more simulations for the same winning rate. Same thing from 13x13 to 19x19. As the time of one simulation is linear in the board area, to keep the same level you have to give a time which increases as power ~2.5 of the board area. So between 9x9 and 19x19, you have to give 32x more time per move for the "same play level" (always defined as winning rate against gnugo). 
This is far from being exponential. (maybe if it was exponential, there would be little interest to work on 9x9 go).

Sylvain

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