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Subject: Re: MTD(f)

Author: Dieter Buerssner

Date: 11:29:15 06/18/05

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On June 18, 2005 at 14:15:31, Vasik Rajlich wrote:

>On June 18, 2005 at 12:25:00, Dieter Buerssner wrote:
>
>>  for (all captures)
>>  {
>>    if (value of captured piece + margin < alpha)
>>      continue; /* Futile to try this move */
>
>     if (eval () + value of captured piece + margin < alpha)
>     {
>       best = eval () + value of captured piece + margin;
>       continue;
>     }
>
>FYI - I caught this at the first pass, but of course the warning (and theme)
>didn't hurt :)

Correct. I built in one error intentionally - but not this one. This one would
be the same error for fail-soft and fail-hard basically. I only caught it, while
reading the post by Rasjid, and replying there. You were writing your post at
the same time.

>As far as I can see, fail-soft affects FL HT moves but not FH HT moves.

Only affecting FL moves could still help. My brain spins, when I try to think,
how it could affect FH moves - so for the moment I agree with you :-)

Agreed with most else you said (cannot judge MTD(f) specific points), however
two questions:

>There are a number of things which tend to kill the softness of fail-soft
>scores:
>
>3) null move

Can you explain why?

>4) bad fail-high moves

Can you elaborate? I don't understand this.

Lazy eval can be made "soft", futility pruning, too.

Cheers,
Dieter



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