Author: Ed Schröder
Date: 02:10:20 12/02/99
Go up one level in this thread
>Posted by Robert Hyatt on December 01, 1999 at 14:57:54: > >In Reply to: Howard's positional sacrifice test posted by Ed Schröder on >December 01, 1999 at 13:09:37: > >On December 01, 1999 at 13:09:37, Ed Schröder wrote: > >>I ran Howard's test, Rebel Century had no problems with all 9 positions. I >>will comment the interesting ones and paste the crucial lines of the LOG. >> >>r1bb2k1/p1q2pp1/4p1np/2ppP2Q/8/2P2N2/2P2PPP/R1B1R1K1 w - - am Bxh6; >>00:00:14 9.00 0.33 1.c4 d4 2.Bd2 a5 3.Ra3 a4 4.Rea1 Bd7 5.Rb1 >> >>r3q1k1/ppp1rpp1/2n1b2p/8/2P2B2/3B4/PPPQ1RPP/5RK1 w - - bm f4h6; >>00:00:00 1.00 1.02 1.Bxh6 gxh6 2.Qxh6 >>00:00:00 4.04 0.88 1.Bxh6 gxh6 2.Qxh6 f5 3.Bxf5 Bxc4 4.Bg6 >> >>The position which started the whole issue. >>---------------- >> >>r3q1k1/ppp1rpp1/4b1np/8/2P2B2/3B4/PPPQ1RPP/5RK1 w - - am BXH6; >>00:00:16 8.00 0.26 1.Bg3 Rd8 2.Qb4 b6 3.Bxg6 fxg6 4.Bh4 g5 5.Bg3 Bf7 >> >>3rrnk1/ppp1qpp1/4b2p/8/2P2B2/3B4/PPPQ1RPP/5RK1 w - - id BXH6spe; >>00:00:14 8.00 0.48 1.Qa5 c6 2.Qxa7 Ra8 3.Qd4 c5 4.Qc3 Rxa2 5.Bg3 >> >>3r1rk1/p2q1ppp/2pb1n2/5b2/1nB5/2N1BN1P/PP2QPP1/R4RK1 b - - bm BXH3; >>00:00:52 9.00 0.31 1..Rfe8 2.Nd4 Bxh3 3.gxh3 Qxh3 4.Nf3 Qg4+ >>00:02:19 9.19 0.41 1..Bxh3 2.gxh3 Qxh3 3.Rac1 Ng4 4.Ne4 Nxe3 5.Qxe3 Qg4+ >>6.Ng3 Bf4 >> >>Rebel Century needs SEARCH + EVAL to find the find the sac. >>----------- >> >>3r1rk1/p2q1ppp/2pb4/p4b2/1nB5/4BN1P/PP2QPP1/R4RK1 b - - am BXH3; >>00:00:54 9.00 0.82 1..Rfe8 2.Rfd1 Nc2 3.Ng5 Re7 4.Rac1 Nxe3 >> >>1qr1b1k1/4bpp1/pn2p2p/1p1nN3/3P4/P2BBN1Q/1P3PPP/4R1K1 w - - bm Bxh6; >>00:00:00 3.01 0.20 1.Bxh6 gxh6 2.Qxh6 Nf6 3.Ng5 a5 >>00:00:00 4.00 0.23 1.Bxh6 gxh6 2.Qxh6 Nf6 3.Ng5 Qd6 4.Bh7+ Nxh7 >5.Qxh7+ Kf8 >>6.Nexf7 >>00:00:00 5.00 0.30 1.Bxh6 gxh6 2.Qxh6 Nf6 >>00:00:05 6.00 1.30 1.Bxh6 Nf6 2.Bg5 Qd6 3.Bxf6 Bxf6 4.Qh7+ Kf8 5.Qh8+ Ke7 >>00:00:08 7.00 1.39 1.Bxh6 Nf6 2.Bg5 Nbd5 3.Nd2 Bd6 4.b4 >>00:00:21 8.00 1.39 1.Bxh6 Nf6 2.Bf4 Qb7 3.Ng4 Nbd5 4.Nxf6+ Nxf6 5.Ne5+ >>00:00:49 9.00 1.42 1.Bxh6 Nf6 2.Bg5 Nbd5 3.Bxf6 Bxf6 4.Qh7+ Kf8 5.Qh8 Ke7 >>6.Ng4 >> >>Another working case of an early positional sacrifice. SEARCH proves Rebel >>is right. >>--------------- >> >>1qr1b1k1/4bpp1/p3p2p/1p1nN3/3P4/P3BN1Q/1P3PPP/4R1K1 w - - am Bxh6; >>00:00:00 1.01 0.13 1.Bxh6 gxh6 2.Qxh6 >>00:00:00 2.00 -0.34 1.Bxh6 gxh6 2.Qxh6 f6 3.Ng6 >>00:00:00 3.00 -1.02 1.Bxh6 gxh6 2.Qxh6 Bf8 3.Qh5 Bg7 >>00:00:00 3.01 -0.39 1.Qg3 Nxe3 2.fxe3 Rc2 >>00:00:00 4.00 -0.40 1.Qg3 Nxe3 2.fxe3 Rc2 3.b4 >>00:00:00 4.02 -0.34 1.Bd2 Rc2 2.Qg4 Nf6 3.Qg3 Bd6 >>00:00:00 5.00 -0.28 1.Bd2 Rc2 2.Qg3 g5 3.b4 >>00:00:01 6.00 -0.34 1.Bd2 Bd6 2.Qg4 Nf6 3.Qg3 Rc2 >>00:00:03 7.00 -0.34 1.Bd2 Rc2 2.Qg4 Kf8 3.b4 Bd6 >>00:00:09 8.00 -0.40 1.Bd2 Rc2 2.Qg4 Kh8 3.Qh5 Rxb2 4.Nxf7+ >>00:00:37 9.00 -0.34 1.Bd2 Rc2 2.Qg4 Kh8 3.b4 Qc7 >>00:02:17 10.00 -0.38 1.Bd2 Rc2 2.Qg4 Kf8 3.b4 Qc7 >> >>This is a very interesting one. The first 2 plies Rebel Century sacs the >bishop >>but then is corrected by SEARCH after seeing 2..Bf8 and 3..Bg7 on the third >>ply. Isn't CC sometimes wonderful? >>------------------- >> >>r1br2k1/p1q2pp1/4p1np/2ppP2Q/2n5/2PB1N2/2P2PPP/R1B1R1K1 w - - bm Bxh6; >>00:00:17 8.08 0.00 1.Bxh6 gxh6 2.Qxh6 Rd7 3.Bxg6 >>00:01:43 9.00 0.62 1.Bxh6 a5 2.Bg5 Re8 3.Bxg6 fxg6 4.Qxg6 Rf8 >> >>Thanks Howard for interesting set. If you have more please post. >> >>Ed > > >This output wasn't exactly what I was looking for. I am much more interested >in your 1-2-3 ply results for these position... > >Why? > >Because here is what your program will do: (a) I like Bxh6, but after I get to >depth=7 I see that it is bad... so (b) I will first play two captures that >eat 4 plies, then a check to eat a couple more, and _then_ I can now play Bxh6 >and I don't see anything bad happening. This ONLY happens if the software (in this case King Safety)... a) is TOO speculative (too high values) b) missing important knowledge -> inaccurate judgement c) is not in balance with other positional rules (values) Above I have given you one case Rebel is wrong at the very first plies, in all the other 8 cases this wasn't an issue otherwise I would have posted that. Here is the one I am talking about, I quote from above: [ begin ] 1qr1b1k1/4bpp1/p3p2p/1p1nN3/3P4/P3BN1Q/1P3PPP/4R1K1 w - - am Bxh6; 00:00:00 1.01 0.13 1.Bxh6 gxh6 2.Qxh6 00:00:00 2.00 -0.34 1.Bxh6 gxh6 2.Qxh6 f6 3.Ng6 00:00:00 3.00 -1.02 1.Bxh6 gxh6 2.Qxh6 Bf8 3.Qh5 Bg7 00:00:00 3.01 -0.39 1.Qg3 Nxe3 2.fxe3 Rc2 00:00:00 4.00 -0.40 1.Qg3 Nxe3 2.fxe3 Rc2 3.b4 00:00:00 4.02 -0.34 1.Bd2 Rc2 2.Qg4 Nf6 3.Qg3 Bd6 00:00:00 5.00 -0.28 1.Bd2 Rc2 2.Qg3 g5 3.b4 00:00:01 6.00 -0.34 1.Bd2 Bd6 2.Qg4 Nf6 3.Qg3 Rc2 00:00:03 7.00 -0.34 1.Bd2 Rc2 2.Qg4 Kf8 3.b4 Bd6 00:00:09 8.00 -0.40 1.Bd2 Rc2 2.Qg4 Kh8 3.Qh5 Rxb2 4.Nxf7+ 00:00:37 9.00 -0.34 1.Bd2 Rc2 2.Qg4 Kh8 3.b4 Qc7 00:02:17 10.00 -0.38 1.Bd2 Rc2 2.Qg4 Kf8 3.b4 Qc7 This is a very interesting one. The first 2 plies Rebel Century sacs the bishop but then is corrected by SEARCH after seeing 2..Bf8 and 3..Bg7 on the third ply. Isn't CC sometimes wonderful? [ end ] >This has happened to me on many occasions on ICC. Sure, at the root you can > >dismiss Bxh6 maybe, but if you can't dismiss it at the tips with equal >accuracy, >you are going to (on occasion) make a committal move at ply-1 that means you >_must_ follow through with Bxh6 at ply=9... > >What I want is as much tactical accuracy as I can get, with some speculative >evaluation terms that are right most of the time, but even when they are wrong >I maintain a chance to not lose. Because then this sort of 'horizon effect' >doesn't hurt. Of course, I might miss a speculative sac that wins, or I might >miss one by my opponent that loses (less likely as I use assymetric king >safety) >But at least I try to avoid being "hoisted on my own petard"... My vision is different. I believe positional sacrifices are doable as long as you stick to certain rules. The best example is your friend Hsu. In game 2 of the rematch against Kasparov 3 pawns were sacrificed in exchange for a strong king attack. Maybe you should ask him about his opinion :) Ed
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