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Subject: Re: passed pawn evaluation. - using other piece info and pawn hash

Author: scott farrell

Date: 16:27:54 01/12/04

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On January 12, 2004 at 10:02:07, Robert Hyatt wrote:

>On January 12, 2004 at 03:09:10, scott farrell wrote:
>
>>On January 11, 2004 at 21:18:30, macaroni wrote:
>>
>>>I have recently been fiddling arround with some passed pawn code, however I just
>>>can't seem to get it working very well. Can you give me an idea of what sort of
>>>values you give different types (in different stages) of passed pawns?
>>>cheers
>>>Tor
>>
>>I think it needs lots of knowledge.
>>
>>What I did is use several pieceSquareTables, for different types, like blocked,
>>isolated, defended, passed, connect passed (probably the most important),
>>defended passed, etc
>>
>>I then tweeked values to solve certain problems. With various psTables, you end
>>up with lots of levers to play with.
>>
>>Scott
>
>Watch out about "connected passers."
>
>give white two pawns on d2/e2.  Give black two pawns on a2/h2.  Both kings
>in the center.  Which side do you like?  :)
>
>This happens a lot vs GM players, once they see the hole.  They will
>happily give you those two connected passers.  :)
>
>Connected passers are good when you have pieces...  But with no pieces,
>look out.

"with no pieces, look out"

given I just do something like :

if ( b.getMajorMaterial(-sideToEval) != 0 )

and change score in pawn hash, I guess I either have to hash in changes to
majorMaterial into the pawn hash, or put the knowledge in a different method
that doesnt go into the values cached by the pawn hash.

How does crafty take care of this? I'd try trolling the source, but it might be
hard to find all the things you do/dont hash into the pawn hash signature.

Thanks
Scott




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