[computer-go] 19x19 MC improvement

[David Fotland]

Congratulations!  I'm really impressed with how fast the AyaMC improved.

Regards,

David

> -----Original Message-----
> From: computer-go-bounces at computer-go.org [mailto:computer-go-
> bounces at computer-go.org] On Behalf Of Hiroshi Yamashita
> Sent: Wednesday, January 23, 2008 12:12 AM
> To: computer-go
> Subject: [computer-go] 19x19 MC improvement
> 
> My program Aya637_4CPU is top on 19x19 CGOS now.
> It is temporary, but I'm so happy!
> Please don't run full power MoGo, Crazy Stone and Leela :-)
> 
> My main improvement was
> 
> 1. Do not move dead stones.
>  Before doing playout, Aya does string capture search up to 7
> plies(ladders
>  are extended). And set the probability of dead stones's liberty to
> 1/10000.
>  This changed winning rate 0.17 to 0.33 (both are 200 games, 40000po
>  against GnuGo 3.7.10) But in 9x9, this method changed nothing.
>  There is no ladder search in playout.
> 
> 2. Change UCT exploration parameter
> 
>   exp_param = sqrt(2.0);
>   uct = exp_param * sqrt( log(sum of all children playout) /
>                         (number of child playout) );
>   uct_value = (child winning rate) + uct;
> 
>  I changed exp_param sqrt(2.0) to sqrt(0.1).
>  This changed winning rate 0.10(660 games) to 0.22(140 games).
>  (10000po, against GnuGo 3.7.10)
>  I was surprised such a small parameter change made big difference.
> 
> AyaMC's sytle is similar to Crazy Stone.
>  - progressive windening.
>  - pattern is only 3x3 from 10000 professional player's game.
> Uct code is like this, http://www.yss-aya.com/uct_aya_e.cpp
> In 10000po of the root initial position, 11 nodes are created,
>  and 18 candidates are searched
> 
> Regards,
> Hiroshi Yamashita
> 
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