Author: José Carlos
Date: 07:31:05 11/06/01
Go up one level in this thread
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.
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