Author: Robert Hyatt
Date: 15:41:54 03/22/99
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On March 22, 1999 at 13:04:45, blass uri wrote: > >On March 22, 1999 at 08:02:52, Robert Hyatt wrote: > >>On March 21, 1999 at 21:04:55, James T. Walker wrote: >> >>>I played 100 games with Crafty 16.5 vs Crafty 16.5 with all 3/4 man tablebases >>>and a few 5 man tablebases in an attempt to determine how much help the >>>tablebases are. Has anyone else done this and if so, what was the result? >>>The final score was Crafty w/tb +32 =38 -30 or 51 to 49. The first 50 games >>>were very different from the second 50 games even though the match was >>>uninterrupted for the 100 games. >>> First 50 Crafty w/tb +21 =15 -14 >>> Second 50 " " +11 =23 -16 >>>It looks like two different programs. Just shows that even 50 games is not a >>>large enough sample to prove anything. I still don't know what the ELO gain is >>>from tablebases ! I'm planning on a couple hundred more games later this week. >>>If anyone else has done this (Bob?) please post your results. >>>Jim Walker >>>P.S. These were only Game/5 minutes. >> >> >>I haven't tried this and have no idea. I think the affect is 'minimal' but >>not insignificant, whatever that means. :) But against 'good' programs I see >>a fair number of tablebase games, that are likely won instead of drawn, or >>drawn instead of lost, only bacause of the tablebases. > >Maybe you do not know about cases when crafty is losing games because it is >slower because of tablebases >or cases when crafty prefer to go to a simple lost endgame instead of lost >tablebase endgame that the opponent can practically do a mistake and draw. > I look at _every_ lost game's log file. Crafty doesn't get horribly slow using tablebases. But I look at _every_ lost game it plays (crafty handle on ICC is the only one since that is the one I run). And I haven't found a case where it lost due to 'slowing down' yet. A serious problem is a ending like KRN vs KRP. It ought to first win the pawn, which can always be done, and then hope for a mistake. But it realizes that winning the pawn leaves it (most times) in a drawn KRN vs KR ending, so that it will delay until it has to play NxP leaving it in an also-drawn KR vs KR ending. But it can win KRN vs KR in many positions, particularly if the opponent isn't using tablebases. KR vs KR is hopeless. Yet it can't tell the difference (at present). One day I am going to 'rank' draws, so that a KRP vs KR (drawn) scores better than a KR vs KR (also drawn but hopelessly so). This is a 'to do' item. >Uri
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