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Re: [Bug-gnubg] Dropped by move filter


From: Christian Anthon
Subject: Re: [Bug-gnubg] Dropped by move filter
Date: Wed, 25 Jun 2008 11:21:19 +0200

I agree,

this is a position where 2ply is expected to do much better, even
cubeless, since it understands the variation tree much better.

It sounds like a good idea though, to make a collection of
moves/evals/cubes where 0ply is way of compared to 2ply or rollouts.

Christian.

On Wed, Jun 25, 2008 at 12:00 AM, Robert-Jan Veldhuizen
<address@hidden> wrote:
>
>
> On Tue, Jun 24, 2008 at 11:32 AM, Achim Mueller <address@hidden> wrote:
>
>> The point is not a technical bug but the fact that gnubg totally
>> misevaluates a position at 0ply that actually should be handled easily.
>> I put some more positions at http://www.acepoint.de/index.php?id=37. This
>> section will be extended from time to time.
>> Another idea is to open a section at www.gnubg.org that can be filled by
>> readers and users also.
>>
>
> Actually this one is not so easy I think. A quick 0/2-ply rollout suggests
> that this is a heavily cube-influenced checker play:
>
>     1. Rollout          21/15 8/4                    Eq.:  +0,431
>         61,3%   7,5%   0,4% -  38,7%   3,4%   0,1% CL  +0,283 CF  +0,431
>       [  0,1%   0,1%   0,1% -   0,1%   0,1%   0,0% CL   0,003 CF   0,007]
>         Full cubeful rollout with var.redn.
>         1296 games, Mersenne Twister dice gen. with seed 826408977 and
> quasi-random dice
>         Play: 0-ply cubeful prune [expert]
>         Cube: 2-ply cubeful prune [world class]
>     2. Rollout          21/11                        Eq.:  +0,393 ( -0,037)
>         60,6%   5,7%   0,4% -  39,4%   4,8%   0,1% CL  +0,230 CF  +0,393
>       [  0,1%   0,1%   0,1% -   0,1%   0,1%   0,0% CL   0,003 CF   0,008]
>         Full cubeful rollout with var.redn.
>         1296 games, Mersenne Twister dice gen. with seed 826408977 and
> quasi-random dice
>         Play: 0-ply cubeful prune [expert]
>         Cube: 2-ply cubeful prune [world class]
>     3. Rollout          21/17*/11                    Eq.:  +0,365 ( -0,066)
>         64,1%  11,7%   0,4% -  35,9%  12,2%   0,2% CL  +0,293 CF  +0,365
>       [  0,1%   0,1%   0,0% -   0,1%   0,1%   0,0% CL   0,003 CF   0,007]
>         Full cubeful rollout with var.redn.
>         1296 games, Mersenne Twister dice gen. with seed 826408977 and
> quasi-random dice
>         Play: 0-ply cubeful prune [expert]
>         Cube: 2-ply cubeful prune [world class]
>
> As you can see, the #3 play, gnubg 0-ply's favourite, still has the highest
> cubeless equity. It's not surprising that without a lookahead, gnubg fails
> to see the future cube implications here.
>
> I guess what's going on, is that a hit leads to overkill after a dance and
> subsequent cube. So, cubeful, you don't reap full benefits of this play when
> it works. The alternative play 21/15 8/4 is less volatile and supposedly
> leads to more efficient cube usage (after a miss).
>
> Greetings,
> --
> Robert-Jan Veldhuizen




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