Author: Stefan Meyer-Kahlen
Date: 13:35:29 05/02/00
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On May 02, 2000 at 15:18:54, blass uri wrote: >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 So you thing I can leave the positon in my test suite by changing "bm Bxe6" to "am Bxe6"? Stefan
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