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Subject: Re: Move ordering metric

Author: Daniel Clausen

Date: 08:29:18 11/13/03

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On November 13, 2003 at 11:10:53, Uri Blass wrote:

>On November 13, 2003 at 10:53:22, Daniel Clausen wrote:
>
>>On November 13, 2003 at 10:13:34, Uri Blass wrote:
>>
>>>On November 13, 2003 at 09:44:22, Daniel Clausen wrote:
>>>
>>>>On November 12, 2003 at 18:40:32, Peter Kappler wrote:
>>>>
>>>>[snip]
>>>>
>>>>>>I get an average of better than 90%. It takes tuning. Work on killers and
>>>>>>history pays off. Make sure you search bad captures before other moves also.
>>>>>>Taking capture out of killers gave me a boost also.
>>>>>>
>>>>>
>>>>>Hmmm, I think I do bad captures at the end, and as I recall it was a clear win.
>>>>
>>>>IIRC, for most people trying bad captures at the end was better with SEE, but
>>>>worse with MVV/LVA.
>>>>
>>>>Sargon
>>>
>>>How do you know that a capture is bad with MVV/LVA?
>>
>>When someone uses SEE, a capture is bad when the SEE-value for it is negative.
>>When someone uses MVV/LVA, a capture is bad when the MVV/LVA-value for it is
>>negative.
>>
>>It's that simple. :)
>>
>>Sargon
>
>It is not so simple.
>
>By this definition every pawn capture by knight,bishop,rook,queen,king is a bad
>capture.
>
>It does not make sense so it does not make sense even to try to put it after non
>captures.
>
>You can have a function to detect part of the captures as bad captures and also
>use MVV/LVA for the captures that you do not detect as bad.
>
>The function that detect bad captures is not SEE because SEE gives you the
>expected value of the capture and not only the information if the capture is
>good or bad.
>
>SEE can order QxN before QxQ when both are good captures when the special
>function does not do it.
>
>In that case the question if to put bad captures before history moves or not to
>do it is dependent on the definition of bad capture.
>
>Uri


I retract everything I said in this thread. :)

I still had the (false) idea in my head that to calculate the score of a capture
in MVV/LVA, you subtract the value of your piece from the value of the captured
piece, which leads to the problems you pointed above.

But I guess MVV/LVA just means that the order of captures to try is

PxQ, B/NxQ, RxQ, QxQ, KxQ, PxR, B/NxR, RxR, QxR, KxR etc

With this definition there's simply no way to distinguish between good and bad
captures.

Sargon



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