Author: blass uri
Date: 12:18:54 05/02/00
Go up one level in this thread
On May 02, 2000 at 14:25:38, Pete Galati wrote: >On May 02, 2000 at 09:07:42, Stefan Meyer-Kahlen wrote: > >> >>In my set of tactical test positions there is the following example: >> >>[D] 2rqk2r/pb1nbp1p/4p1p1/1B1n4/Np1N4/7Q/PP3PPP/R1B1R1K1 w k – bm Rxe6 >> >>I can’t remember where I have found this position, but the solution is supposed >>to be Rxe6. Until know every version of Shredder has found this move sooner or >>later and kept it as a best move until the end of my test time. >> >>Last night I have tested my latest version and found something interesting. >>Shredder played Rxe6 after a while as usual, but got a terrible fail low for >>that move at ply 11. >> >>So here is my question: >>Is Rxe6 really the best move and I have introduced a bug somewhere in my code or >>is Rxe6 a mistake? I didn’t find an improvement for white after 1. Rxe6 fxe6, >>but this can be due to my limited chess knowledge. >> >>Here is Shredder’s output: >> >> 6.01 0:00.71 -0.23 1.Bh6 a6 2.Bd3 Bf6 3.Nf3 a5 (63.557) 88.3 >> 6 -> 0:01.76 -0.23 1.Bh6 a6 2.Bd3 Bf6 3.Nf3 a5 (159.299) 90.2 >> 7.01 0:02.71 -0.09 1.Bh6 a6 2.Bd3 Bf6 3.Nb3 N5b6 4.Nxb6 Qxb6 >> (240.167) 88.3 >> 7 -> 0:04.90 -0.09 1.Bh6 a6 2.Bd3 Bf6 3.Nb3 N5b6 4.Nxb6 Qxb6 >> (435.029) 88.6 >> 8.01 0:07.96 -0.01 1.Bh6 a6 2.Bf1 N7f6 3.Rad1 Qa5 4.Bg7 Nf4 >> (704.124) 88.3 >> 8 -> 0:10.15 -0.01 1.Bh6 a6 2.Bf1 N7f6 3.Rad1 Qa5 4.Bg7 Nf4 (911.624) 89.7 >> 9.01 0:17.93 -0.17 1.Bh6 a6 2.Be2 Bg5 3.Bf3 Nf4 4.Qg3 Bxh6 5.Bxb7 >> (1.594.580) 88.8 >> 9 -> 0:32.29 -0.17 1.Bh6 a6 2.Be2 Bg5 3.Bf3 Nf4 4.Qg3 Bxh6 5.Bxb7 >> (2.918.536) 90.3 >>10.01 0:42.76 -0.14 1.Bh6 a6 2.Be2 Qa5 3.b3 e5 4.Nf3 e4 5.Nd2 f5 >> (3.876.621) 90.6 >>10.08 2:02.76 -0.13++ 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ >> Kf8 6.Nxb7 (11.210.309) 91.3 >>10.08 2:26.60 +0.22++ 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ >> Kf8 6.Bh6+ Kf7 7.Nxb7 a6 8.Nxa5 Rc1+ 9.Rxc1 >> (13.366.273) 91.1 >>10.08 3:25.78 +0.40 1.Rxe6 Rc7 2.Re2 O-O 3.Bh6 Re8 4.Rae1 a6 5.Bd3 a5 6.b3 >> (18.827.259) 91.4 >>10 -> 3:45.35 +0.40 1.Rxe6 Rc7 2.Re2 O-O 3.Bh6 Re8 4.Rae1 a6 5.Bd3 a5 6.b3 >> (20.541.368) 91.1 >>11.01 5:35.76 +0.15-- 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ >> Kf7 6.Nxb7 Rc7 7.Nd6+ Kg7 8.Ne8+ Rxe8 9.b3 Rxc1+ >> (31.352.209) 93.3 >>11.01 9:18.76 -0.35-- 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ >> Kf7 6.Nxb7 Rc7 7.Nd6+ Kg7 8.Ne8+ Rxe8 9.Qxe8 Nf6 >> 10.Qb8 Bd6 (54.470.299) 97.4 >>11.01 14:41.53 -1.36 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ >> Kf7 6.Nxb7 Rc7 7.Nxa5 Rxd7 8.Nc6 Rc7 9.Nxe7 >> (86.129.099) 97.7 >>11.02 14:52.57 -1.35++ 1.Bh6 a6 2.Be2 Qa5 3.b3 Nf4 4.Bxf4 Bxg2 5.Qxg2 >> (87.133.005) 97.6 >>11.02 15:07.65 -1.00++ 1.Bh6 a6 2.Bxd7+ Qxd7 3.Nxe6 Qxa4 4.Ng7+ Kd8 5.Qd7+ >> Qxd7 (88.458.785) 97.4 >>11.02 16:23.21 -0.10 1.Bh6 a6 2.Bxd7+ Qxd7 3.b3 e5 4.Qxd7+ Kxd7 5.Rxe5 Bf6 >> 6.Rxd5+ Bxd5 7.Nb6+ Kd6 8.Nxc8+ Kd7 9.Re1 >> (95.283.049) 96.9 >> >>(I have formatted it a bit, hopefully it helps...) >> >>Stefan > >I'm a weak Chess player, and I could not conceive of the move Rxe6, but that >means nothing at all, it just means that I couldn't look at that position an see >a way for Rxe6 to benifit me. I don't have the ability to see ahead very far at >all. After 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ Kf7 6.Nxb7 Rc7 white is losing and white has no logical alternative to avoid this line after 1.Rxe6 except 2.Bh6. computers need a long time to see it because they believe that after 6...Rc7 7.Nd6+ Kg7 8.Ne8+ Rxe8 9.Qxe8 Nf6 10.Qb8 is good for white. 2.Bh6 is not a move that computers like because white get an attack for a rook and most programs believe that a rook is more than an attack. > >But on the other hand, the Dos Comet sat there looking at that position for >around 2 3/4 hours on my slow computer and never got past Rxe6. Comet would >have more hashtable available to it if I had run Comet all the way in Dos, I >have no idea what difference that would have made. It is not surprising 1.Rxe6 fxe6 2.Nxe6 is a trap that most programs fall because they do not know which lines to extend. Avoiding Rxe6 in less than 15 minutes(by the latest versions of Rebel and shredder) is very good relative to most programs. Uri
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