Author: Omid David Tabibi
Date: 11:40:20 12/30/02
Go up one level in this thread
On December 30, 2002 at 13:23:29, Ed Schröder wrote:
>On December 30, 2002 at 11:27:46, Martin Giepmans wrote:
>
>>>For free-style pseudo code it is defendable, maybe in more c-code style would
>>>make it more clear?
>>>
>>> { if (ALPHA > SCORE + THREAT &&
>>> ALPHA < SCORE + THREAT + MARGIN) -> reduce depth with one ply. }
>>
>>Yes, this makes it more clear.
>
>Okay, then I will make it that way.
>
>
>>However, I wonder if the second part of the condition (the margin part)
>>is useful. Maybe it is if the current window is smaller than margin, but
>>otherwise?
>
>The idea is based on experience, not on logic, you know how it goes. It just
>works for me.
>
>
>>Of course, the extra condition makes the tric safer, but I think it could
>>also cause more search instability.
>
>In my concept it hardly gave any trouble, but then the whole REBEL concept is
>totally different. You will notice when I arrive on the issue null-move and how
>I use it :)
>
>
>>BTW, this probably doesn't work in an engine that uses PVS.
>>Am I right?
>
>Please give the definition of PVS, I sometimes have the feeling there are more
>than one definitions.
>
If my memory serves me well, the original PVS was meant to search with a minimal
window only after a move produces a score greater than alpha (i.e., a PV move is
found). Alexander Reinfeld's NegaScout differs in the sense it searches all
moves expect the first one, with a minimal window. When saying PVS, many usually
refer to NegaScout.
>Ed
>
>
>>Cheers,
>>Martin
>>
>>>
>>>ALPHA=100
>>>SCORE=90
>>>THREAT=0
>>>MARGIN=20
>>>
>>>-> reduction
>>>
>>>ALPHA=100
>>>SCORE=60
>>>THREAT=0
>>>MARGIN=20
>>>
>>>-> no reduction
>>>
>>>Ed
>>>
>>>
>>>>Martin
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