Author: Pete R.
Date: 15:45:38 05/02/00
Go up one level in this thread
On May 02, 2000 at 16:35:29, Stefan Meyer-Kahlen wrote: >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 Yes, I for one think Rxe6 is to be avoided. I don't think 1. Rxe6 fxe6 2. Bh6 is any better for white after 2...a6. With sufficiently deep analysis I think 1. Qd3 may prove best.
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