Author: Ed Schröder
Date: 08:37:58 05/02/00
Go up one level in this thread
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 Hi Stefan, This position was part of Rebel10's anti-GM discussion a few years ago. Rxe6 maybe is not the best move but it surely can confuse a GM so much he loses oversight and start to blunder in all the tactical complications. Like Shredder also Rebel fails low at a certain moment, see below. Ed PS, on a 128 Mb machine what are the best hash table settings? I use 48 Mb for the hash table and 16 Mb for the position table but so now and then I still notice swapping so I wonder. _______________________________________________________________________________ 00:00:03 7.20 -0.77 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ Kf7 6.Qe6+ Kg7 7.Nxb7 Qxa4 8.Qxd5 (3) 00:00:09 8.00 -0.01 1.Rxe6 a6 2.Rxe7+ Nxe7 3.Bxd7+ Qxd7 4.Qxd7 Kxd7 5.Nb6 Kc7 6.Nxc8 Rxc8 7.Bd2 Nd5 8.Rc1 Kd6 9.Rxc8 Bxc8 (6) 00:00:22 9.00 0.20 1.Rxe6 a6 2.Bxa6 fxe6 3.Bxb7 Rc4 4.Nxe6 Qa5 5.Qf3 (10) 00:01:03 10.00 0.19 1.Rxe6 Rc7 2.Re2 a6 3.Bd3 Rxc1+ 4.Rxc1 Nf4 5.Qe3 Nxe2+ 6.Qxe2 Qa5 7.b3 (24) 00:02:00 11.00 -0.32 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 Rxc1+ 11.Rxc1 Qxa4 (93) 00:04:06 12.00 -0.91 1.Rxe6 fxe6 2.Nxe6 Qa5 3.Bxd7+ Kxd7 4.Nec5+ Ke8 5.Qd7+ Kf7 6.Nxb7 Rc7 7.Nxa5 Rxd7 8.Nc6 Kg7 9.Bd2 (210) 00:10:00 12.03 -0.85 1.Bd2 a6 2.Bd3 O-O 3.Bh6 Re8 4.Rac1 Rxc1 5.Rxc1 Bg5 6.Nc6 (297)
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