Author: Uri Blass
Date: 13:21:13 11/06/01
Go up one level in this thread
On November 06, 2001 at 10:31:05, José Carlos wrote: >On November 06, 2001 at 09:45:35, Uri Blass wrote: > >>On November 06, 2001 at 09:35:13, José Carlos wrote: >> >>>On November 06, 2001 at 07:23:07, Gian-Carlo Pascutto wrote: >>> >>>>On November 06, 2001 at 07:18:29, Leen Ammeraal wrote: >>>> >>>>>My program sees that black deserves a very high score, >>>>>derived from the egtb, but fails to make the trivial >>>>>move 1. ... g1Q because it does not find an entry >>>>>for the resulting position in the egtb, and because >>>>>the computed score after this promotion move >>>>>is lower than the egtb score retrieved after the >>>>>move Rg3, so the latter move is made and the >>>>>game results in a draw instead of in a win for >>>>>black. Has anyone encountered similar problems? >>>>>It seems to me that for any egtb file with >>>>>pawns, there should be a corresponding file >>>>>for the case that one of the pawns has turned >>>>>into a queen. If not, the result may be >>>>>completely wrong, as in the above example. >>>>>Leen >>>> >>>>This is wellknown. >>>> >>>>A possible solution is to turn off egtb's if you are in an egtb >>>>position and you note that the distance to mate does not shorten >>>>anymore. >>>> >>>>-- >>>>GCP >>> >>> I don't understand. If the draw-by-repetition and draw-by-50-moves-rule tests >>>are done correctly, this is, _before_ probing, the program will surely move the >>>rook stupidly during 50 moves. Then it will see the draw, and chose another >>>move. I don't see how the program can accept the draw here. >>> >>> José C. >> >>It is possible that the program's move is only the 99 ply with no conversion so >>the program looks at the tablebases and does not consider it as a draw and the >>draw is in the 100th ply that the program does not consider because it looks on >>the tablebases. >> >>It is also possible that in the 100th ply the program finds that conversion does >>not win(there is another win by tablebases but it is a draw by the 50 move >>rule). >> >>Uri > > Ok, I get it. After _my_ move I get a tb hit when it's ply 99. Then my >opponent moves and it's ply 100, so it's a draw after my opponent's move. >Correct. > Bob gives a solution in other post, but there's another possibility. When you >get a tb hit, check if it is ply 99. If it is, anything exept checkmate is a >draw. Well, you lose some time checking the 100 ply counter, but it's a tiny >time compared to the tb probe. > > José C. It is not so simple The next possible situation can also happen It is ply 97 you play a move that is a win by tablebases. The opponent reply with check so you cannot play a conversion in the next move and inspite of the fact that the position is a tablebase win you get a draw by the 50 move rule. Uri
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