Author: Rafael Andrist
Date: 09:16:32 05/30/02
Go up one level in this thread
On May 30, 2002 at 10:13:39, Robert Hyatt wrote: >On May 30, 2002 at 02:15:38, Uri Blass wrote: > >>On May 30, 2002 at 00:44:06, Robert Hyatt wrote: >> >>>On May 29, 2002 at 02:34:34, Robin Smith wrote: >>> >>>>The position is easily winning for white. But tablebases cause programs to want >>>>to play 1.Rxf5?? after which there is a tablebase mate in 65 .... except the 50 >>>>move rule kicks in first and the game ends up a draw. Are there any programs >>>>that avoid this type of blunder? [D] 5k2/3K4/8/R4b2/1R6/8/3B4/5r2 w - - 0 1 >>> >>> >>>Can't avoid it. The current tablebases don't include 50-move-rule >>>issues, so this is just a fact of life for tablebases. >> >>You can avoid it by translating mate in 67 to something like +2 so you are going >>to prefer safer ways to win the game if you can see them by search. >> >>Uri > > >That won't come _close_ to fixing the problem. Suppose the alternative is >+1.5, so you go for +2 and a draw? Many of these problem endings have a pawn >on the board as well, which means just checking for pieces-only and saying >"no mate > 50" fails on two counts: (1) there are going to be 6 piece endings >that are won, even with no pawns on the board; they will be won because a >piece gets won or traded prior to 50 moves passing. (2) Just because you have >a pawn doesn't mean the mate in N is reachable within the 50 move rule. > >I don't think simple "band-aid" fixes will work. They will be wrong as often >as the programs are wrong now because of the 50 move rule. I plan to implement the following "solution" to this problem in my program: If I get a mate from EGTB and this becomes the value of the search tree, I will check for captures inside the PV i.e. and, if this shows that there's a problem with the 50-move rule, re-search while ignoring the EGTB hash entrys and check each potentialy wrong mate distance. Of course after completing at least one ply of normal search without questioning the EGTB. Rafael B. Andrist
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