Author: Uri Blass
Date: 22:30:12 02/28/01
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On February 28, 2001 at 21:35:46, Robert Hyatt wrote: >On February 28, 2001 at 18:17:37, Uri Blass wrote: > >> >>Can you show the 64 plies? >> >>45... Qe3! 46.Qxd6 Re8! 47.h4? h5! 48.Bf3 Qc1+ 49.Kf2 Qd2+ 50.Be2 Qf4+ 51.Kg1 >>Qe3+ 52.Kh2 Qf4+ 53.Kh3 Qxf5+ 54.Kh2 Qf4+ 55.Kg1 Qe3+ 56.Kf1 Qc1+ 57.Kf2 Qf4+ >> >>Are these the first 25 plies? >> >>If they are then I am interested in the last 39 plies. >>If they are not what is the wrong move except 47.h4 when after 47.Qd7+ programs >>cannot prove a repetition? >> >>Uri > > >I really can't... the version I used to run that test back in 1997 simply >maintained a variable "maxply" which was kept as the deepest ply the search >reached during the run. No idea what the moves along that deep search looked >like, but I would suspect it was a lot of nonsense checking/sacrificial moves >to drive the search that deep. > >The problem with the DB position is that _every_ move is not a check, a >capture, or even a strong threat. Some are _very_ quiet moves, which makes >the search tend to stop at those points... The last "quiet" move that I can think is at move 60 of black that can be after this line(60...Qc1) I say "quiet" because Qc1 threat the bishop so it is not totally quiet and it is possible that some program extend also Qc1(maybe less than checks or captures) 45... Qe3! 46.Qxd6 Re8! 47.h4? h5! 48.Bf3 Qc1+ 49.Kf2 Qd2+ 50.Be2 Qf4+ 51.Kg1 Qe3+ 52.Kh2 Qf4+ 53.Kh3 Qxf5+ 54.Kh2 Qf4+ 55.Kg1 Qe3+ 56.Kf1 Qc1+ 57.Kf2 Qf4+ 58.Ke1 Qc1+ 59.Bd1 Qxc3+ 60.Kf1 Here is the position after 59.Bd1(28 plies after the root) [D]4r3/5kp1/R2Q1p2/1p1Pp2p/1Pp4P/2P5/6P1/2qBK3 b - - 0 1 In this position Crafty18.01 under chessbase has no problem to see a draw score at depth 8/20 and it does not need 36 plies in the selective search. I also doubt if you need 60 plies in the original position because I cannot see the relevant 60 ply line. I am interested to see the longest line that is relevant to find if black has not another option to make it shorter. Uri
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