Author: Uri Blass
Date: 00:02:52 01/13/04
Go up one level in this thread
On January 13, 2004 at 02:15:36, scott farrell wrote: >On January 13, 2004 at 00:00:14, Uri Blass wrote: > >>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. >yeh, maxThreat is only the maximum piece that can be attacked after the move is >made, Its not SEE at all, I guess Re5 should return 1, attacking the pawn. I >think maxThreat is not used much these days, but still in the debug. I'll check >Re5 anyway. > >> >>I also do not understand why threat against the king is 9 when SEE of exposing >>the king to check is -50. >> >Maxthreat doesnt differentiate between kings and queens, its only to detect >moves that are threatening, as opposed to actually capturing anything, if some >threats a king its nearly the same as threat to a queen, you better do something >about it - or probably lose the game. > >I guess you saw the nice 1.0 SEE+ gain for Rxf5 - you have to like that like. Yes I am debugging my SEE. I already found errors in previous versions and I hope that latest version have no errors. In the position that you posted movei find also 1 for Rxf5 -5 for Rd7 and 0 for other moves. I think that asking the program to print the moves with SEE different than 0 can be productive for debugging. I will probably calculate manually SEE for all legal moves of 100 different positions to verify that movei does not get them wrong. Uri
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