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Subject: Re: Does crafty stop calculating SEE after capturing a king?

Author: Uri Blass

Date: 21:00:14 01/12/04

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On January 12, 2004 at 20:05:11, scott farrell wrote:

>On January 12, 2004 at 17:34:52, Uri Blass wrote:
>
>>I do not see when it happens in crafty and note that it is not only a question
>>of speed when it is not clear what is faster and if I understand correctly
>>crafty may be wrong when a sequence of captures that is finished in trading
>>kings happens and it may happen in the endgames.
>>
>>[D]8/5r2/5k2/3R1p2/5K2/8/8/8 w - - 0 1
>>
>>Rxf5+ is a good capture but based on SEE that let trading kings it can be
>>pruned.
>>
>>Uri
>
>
>thanks uri/sune, added some stuff about a king,
>
>my acutal check was if king is capturing, and -stm still has pieces in the
>capture list, return -king for that part. I also added the dont xray the king,
>but I didnt see any effect - but clearly it is smart.
>
>My goal is to have 2 SEE, one fast, and one smart.
>
>output from chompster:
>
>the key is:
>maxthreat/SEE+/SEE ala crafty/NA
>
>as you can see it scores the Kxf5 as +1, and kxf5 as -50, interestingly with
>checks in the qsearch either way found kxf5+ with the same 33 nodes. I think
>crafty might need 2 plies instead of one, with an incorrect SEE and no checks in
>the qsearch.
>
>notice RE5 says 0 on both SEE and SEE+, I think SEE (ala crafty) just minimax's
>the king swap and accidently gets the right score.
>
>8/5r2/5k2/3R1p2/5K2/8/8/8/ w - - 0 0
>normal moves:
>RD8 (D5D8) , maxThreat=0/0/0/0
>RD7 (D5D7) , maxThreat=0/-5/-5/0
>RD6 (D5D6) , maxThreat=9/0/0/0
>RA5 (D5A5) , maxThreat=0/0/0/0
>RB5 (D5B5) , maxThreat=0/0/0/0
>RC5 (D5C5) , maxThreat=0/0/0/0
>RE5 (D5E5) , maxThreat=0/0/0/0
>RxF5 (D5F5) , maxThreat=9/1/-4/0
>RD4 (D5D4) , maxThreat=0/0/0/0
>RD3 (D5D3) , maxThreat=0/0/0/0
>RD2 (D5D2) , maxThreat=0/0/0/0
>RD1 (D5D1) , maxThreat=0/0/0/0
>KE5 (F4E5) , maxThreat=9/-50/0/0
>KxF5 (F4F5) , maxThreat=9/-50/-4/0
>KG5 (F4G5) , maxThreat=9/-50/-50/0
>KE4 (F4E4) , maxThreat=1/-50/-50/0
>KG4 (F4G4) , maxThreat=1/-50/-50/0
>KE3 (F4E3) , maxThreat=0/0/0/0
>KF3 (F4F3) , maxThreat=0/0/0/0
>KG3 (F4G3) , maxThreat=0/0/0/0

I do not understand it.

Why maxthreat of Re5 is 0 when maxthreat of the illegal Ke4 is 1?
both threat the pawn at f5 and if we talk about new threat then they do not have
a new threat.

I also do not understand why threat against the king is 9 when SEE of exposing
the king to check is -50.

Uri



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