Author: Uri Blass
Date: 03:17:18 12/04/05
Go up one level in this thread
On December 04, 2005 at 04:49:55, Tony Werten wrote: >On December 03, 2005 at 12:27:56, Robert Hyatt wrote: > >>On December 03, 2005 at 11:12:23, chandler yergin wrote: >> >>>New game >>>[D]3Q4/bp3pp1/6k1/8/7R/6p1/B2p1PP1/q1rn2K1 w - - 0 1 >>> >>>Analysis by Shredder 8: >>> >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 10/10 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 26kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 26kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 26kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 26kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 26kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 12/12 00:00:00 26kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 13/13 00:00:00 41kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 14/14 00:00:00 75kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 15/15 00:00:00 153kN >>>1.Qd3+ f5 2.Qxg3+ >>> +- (#14) Depth: 16/16 00:00:00 247kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Qxd2 >>> +- (#11) Depth: 17/18 00:00:01 596kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ >>> +- (#14) Depth: 18/54 00:07:23 166686kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 19/55 00:07:28 169067kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ >>> +- (#14) Depth: 20/53 00:07:35 171711kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 21/56 00:07:42 174826kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 22/36 00:07:49 178326kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 23/38 00:08:03 184315kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 24/40 00:08:26 194168kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 25/43 00:08:56 207920kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 26/43 00:09:43 229005kN >>>1.Qd3+ f5 2.Qxg3+ Kf6 3.Qd6+ Kg5 4.Rh5+ Kxh5 5.Bf7+ Kg5 6.Qg3+ Kf6 7.Qg6+ Ke5 >>>8.Qe6+ Kf4 9.g3+ Kg4 10.Qg6+ Kf3 11.Qxf5+ >>> +- (#14) Depth: 27/41 00:11:01 263041kN >>> >>>(, MyTown 03.12.2005) >>> Which is what I said; deeper search confirms. >>>I see no Bug, the Program found a Mate in 11 in .01 seconds >>>I cut the analysis short. My error, not the Program. >> >> >>You may not see the bug, or you may not understand the bug. But it is >>absolutely a bug. >> >>Pick up _any_ AI textbook. Alpha/Beta is _guaranteed_ to return the same score >>as a pure minimax search, only far faster. If a minimax search says "mate in >>11", and there is no mate in 11 present, then that is a bug, nothing more, >>nothing less. Many programs will find a mate that is sub-optimal (longer) but >>if one finds one that is shorter than can be forced, it is simply a bug. > >Why would checkmate scores have to be exact ? > >You can choose to return (heuristic)checkmate scores from eval, with some bound >on iteration depth. > > >Tony I agree that in theory checkmate score do not have to be exact but I think that practically when programs say shorter mate than the real mate it is because of bugs. Note that usually evaluation is only an estimate for the real score and if a program says 0.00 it does not mean that it is a draw. A program may have a function to see wins in pawn endgame(I do not have it) and it may evaluate the following position as mate in 20 for white during the search. [D]8/p3k3/8/8/8/8/PPPPK3/8 w - - 0 1 The reason that I believe that no program does it is because I see no practical advantage from doing it because even if you evaluate it as winning and use it for pruning you can give it a bonus of 50 pawns and have a rule to prune lines when the evaluation is more than 50 pawns advantage unless you already found advantage of more than 50 pawns for one side and you search for mate. Uri
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