Test Position: Poisoned pawn

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Albert Silver
Posts: 3019
Joined: Wed Mar 08, 2006 9:57 pm
Location: Rio de Janeiro, Brazil

Test Position: Poisoned pawn

Post by Albert Silver »

In the following position, the pawn on g7 was mistakenly taken, and a draw ended up ensuing as the knight found itself prisoner on the square.

[D]2r1kr2/6p1/pp2Pn1p/3p1P1N/2pP3P/P4R2/1P4K1/5R2 w - - 0 37

The correct move is 1.Nf4!
"Tactics are the bricks and sticks that make up a game, but positional play is the architectural blueprint."
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yanquis1972
Posts: 1766
Joined: Wed Jun 03, 2009 12:14 am

Re: Test Position: Poisoned pawn

Post by yanquis1972 »

at d25 rybka seems to agree with the conclusion but disagree that Nxg7 draws (in fact she goes so far as to evaluate on the cusp of +/-)

Analysis by Deep Rybka 4 x64 AN:

1. +/- (1.21): 1.Nf4 Rg8
2. +/- (0.73): 1.Nxg7+ Ke7 2.Rg3 b5 3.Rg6 c3 4.bxc3 Rxc3 5.Rf3 Rc4 6.Rd3 Rc2+ 7.Kh3 h5 8.Rb3 Rfc8 9.Rg5 R8c3+ 10.Rxc3 Rxc3+ 11.Kg2 Re3 12.Nxh5 Nxh5 13.Rxh5 Kf6 14.Rg5 a5 15.Rg3 Re4 16.Rf3
3. +/= (0.42): 1.Nxf6+ Rxf6 2.Rg3 Rc7 3.Kh3 b5 4.Kg4 Ke7
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kgburcham
Posts: 2016
Joined: Sun Feb 17, 2008 4:19 pm

Re: Test Position: Poisoned pawn

Post by kgburcham »

[D] 2r1kr2/6p1/pp2Pn1p/3p1P1N/2pP3P/P4R2/1P4K1/5R2 w - - 0 37

20.08 0:52 +1.07 1.Nf4 Rg8 2.Rg1 b5 3.Rg3 a5 4.Rg6 Kf8 5.Kf3 Rb8 (26.135.774) 511
21.01 1:38 +1.15 1.Nf4 Rg8 2.Rg1 b5 3.Rg3 (48.172.864) 501
22.01 3:23 +1.35++ 1.Nf4 (97.136.911) 489
22.01 4:28 +1.35 1.Nf4 Rg8 2.Rg1 Kd8 3.Rg3 Ke7 4.Kh3 (126.254.726) 482
23.01 7:48 +1.41 1.Nf4 Rg8 2.Rg1 Ke7 3.Rg3 Kd6 4.Kh3 Rc7 5.h5 a5 (216.775.096) 473
24.01 10:15 +1.39 1.Nf4 Rg8 2.Rg1 Ke7 3.Rg3 Kd6 4.Kh3 Rc7 5.h5 a5 (287.271.162) 478
25.01 12:09 +1.39 1.Nf4 Rg8 2.Rg1 Ke7 3.Rg3 Kd6 4.Kh3 Rc7 5.h5 a5 (341.218.383) 478
best move: Nh5-f4 time: 15:33.526 min n/s: 474.299 nodes: 432.285.696


22/70 0:14 +0.77++ 1.Nf4 (210.505.077) 14649
22/70 0:21 +0.81 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Rc7 4.Rc1 (327.185.223) 14952
23/70 0:23 +0.85 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Rc7 4.Rc1 Ke7 5.Kf2 Rcc8 (353.984.961) 14924
24/70 0:32 +0.88 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Rc7 4.Rc1 Ke7 5.Kf2 Rcc8 (488.302.002) 15030
25/70 0:37 +0.84 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Rc7 4.Rc1 Ke7 5.Rc3 Rb7 (573.116.264) 15150
26/70 1:05 +0.91++ 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Rc7 4.Re1 Ke7 5.Kh2 Rcc8 (1.010.530.607) 15428
26/70 1:07 +0.90 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Rc7 4.Re1 Ke7 5.Re3 Rb7 (1.038.260.176) 15419
27/82 2:01 +0.97++ 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Rc7 (1.907.664.067) 15671
27/82 2:09 +0.94 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Ke7 4.Re1 Rc7 5.Re3 Rb7 (2.024.434.008) 15673
28/82 3:37 +1.01++ 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Ke7 4.Re1 Rc7 5.Re3 Rb7 (3.458.810.542) 15907
28/82 3:44 +1.01 1.Nf4 Rg8 2.Rg3 b5 3.Rg6 Ke7 4.Re1 Rc7 5.Re3 Rb7 (3.577.185.590) 15905
best move: Nh5-f4 time: 3:45.094 min n/s: 15.905.000 CPU 99.6% n/s(1CPU): 15.968.875 nodes: 3.577.185.590
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zullil
Posts: 6442
Joined: Tue Jan 09, 2007 12:31 am
Location: PA USA
Full name: Louis Zulli

Re: Test Position: Poisoned pawn

Post by zullil »

Albert Silver wrote:In the following position, the pawn on g7 was mistakenly taken, and a draw ended up ensuing as the knight found itself prisoner on the square.

[D]2r1kr2/6p1/pp2Pn1p/3p1P1N/2pP3P/P4R2/1P4K1/5R2 w - - 0 37

The correct move is 1.Nf4!
Stockfish-1.7.1 (8 threads) opts for Nf4 very quickly:

Code: Select all

Searching: 2r1kr2/6p1/pp2Pn1p/3p1P1N/2pP3P/P4R2/1P4K1/5R2 w - -
infinite: 0 ponder: 0 time: 0 increment: 0 moves to go: 0
 2     +1.09   00:01      168 Nf4 a5 
 3     +1.41   00:01      298 Nf4 a5 Rg3 
 4     +0.65   00:01      879 Nf4 Rg8 Ng6 Ne4 
 4     +1.13   00:01     1292 Nxf6+ Rxf6 Rg3 Rc7 Kh3 
 5     +0.81   00:01     1734 Nxf6+ Rxf6 Rg3 Rc7 Kh3 Re7 
 6     +0.65   00:01     5245 Nxf6+ Rxf6 Rg3 Rc7 Kh3 Re7 Rgg1 g6 Rxg6 Rexe6 
 6     +0.93   00:01     6669 Nf4 Rg8 Ng6 h5 Kg3 Ne4+ Kf4 
 7  <  +0.65   00&#58;01    13719 Nf4 Rg8 Ng6 Ne4 Nf4 Nd2 
 7     +0.73   00&#58;01    16588 Nf4 Rg8 Ng6 Ne4 Rc1 Nd2 Re3 Ne4 
 8     +0.97   00&#58;01    24838 Nf4 Rg8 Ng6 Ne4 Rc1 Nd6 Rd1 Kd8 Kg3 Ne4+ Kg4 Kc7 
 9     +0.85   00&#58;01    57103 Nf4 Rg8 Ng6 Ne4 Rc1 Rd8 Re3 Nd6 Re5 Nb5 Nf4 Nxd4 
                              Rxd5 
10  >  +1.09   00&#58;01   115890 Nf4 Rg8 Ng6 Ne4 Rc1 Rd8 Re3 Nd6 Rf1 Rc8 Re5 
10     +0.77   00&#58;01   131838 Nf4 Rg8 Ng6 Ne4 Re3 Rd8 Re2 Rc8 Kf3 c3 Rc1 
10     +0.89   00&#58;01   156729 Nxg7+ Ke7 Rg1 Ne4 Kh3 Rg8 Rg6 Nf6 Kg3 Rcf8 a4 
                              Ne4+ Kf4 
11  <  +0.77   00&#58;01   180087 Nxg7+ Ke7 Kh3 Rg8 Rg1 Ne4 Rg6 Rcf8 
11     +0.85   00&#58;01   230065 Nxg7+ Ke7 Rg1 Ne4 Kh3 Nd2 Rfg3 Ne4 Rg6 h5 Rc1 c3 
                              bxc3 Rxc3+ Rxc3 Nxc3 
12  <  +0.77   00&#58;01   313219 Nxg7+ Ke7 Kh3 Rg8 Rg1 Rcf8 Rfg3 Ne4 Rg6 Rf6 
12  <  +0.69   00&#58;01   337611 Nxg7+ Ke7 Rg1 Rg8 Kh3 Rcf8 Rfg3 Ne4 Rg6 Rf6 
12  >  +0.93   00&#58;01   359353 Nf4 Rg8 Ng6 Ne4 Re3 Rd8 Re2 Rc8 Kf3 c3 Rc1 
12  >  +1.01   00&#58;01   375206 Nf4 Rg8 Ng6 Ne4 Re3 Rd8 Re2 Rc8 Kf3 c3 Rc1 
12     +1.05   00&#58;01   401315 Nf4 Rg8 Ng6 a5 Rc1 Kd8 Kh3 Re8 Rg1 Rg8 a4 Kc7 
13  <  +0.81   00&#58;01    1393k Nf4 Ne4 Nxd5 Nd2 Nxb6 Rb8 Nd7 Nxf3 Nxb8 Nxd4 Nxa6 
                              Nxf5 
13  >  +1.29   00&#58;01    1774k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rh5 Rxg7 
                              Rxh4+ Kf3 
13     +1.29   00&#58;01    2378k Nf4 Rg8 Ng6 a5 Re3 b5 Rc1 b4 Kf3 Rb8 a4 c3 bxc3 
                              b3 Re2 b2 Rb1 
14     +1.25   00&#58;01    3034k Nf4 Rg8 Ng6 b5 Rc1 Kd8 Rg1 Re8 Re3 h5 Nf4 Kc7 Rg3 
                              Re7 Kf3 
15  >  +1.41   00&#58;01    3787k Nf4 Rg8 Ng6 b5 Rg1 b4 axb4 Rb8 Ra3 Rxb4 Rxa6 
                              Rxb2+ Kf3 Rb3+ Kf4 
15  <  +1.09   00&#58;02    4096k Nf4 Rg8 Ng6 b5 Rg1 a5 Kg3 b4 axb4 axb4 Kf4 c3 
                              bxc3 bxc3 Ne5 Ke7 
15     +1.33   00&#58;02    4294k Nf4 Rg8 Ng6 b5 Rg1 Kd8 Re3 Re8 Nf4 Re7 Kh3 Rcc7 
                              Ng6 Re8 Ne5 Ne4 Ree1 
16  <  +1.21   00&#58;02    4522k Nf4 Rg8 Ng6 b5 Rg1 Kd8 Re3 Rb8 Kf3 b4 Ne5 Kc7 
                              axb4 Rxb4 Ra3 Rxb2 Rxa6 Rb3+ Kf4 Nh5+ Kg4 Nf6+ 
16  >  +1.45   00&#58;02    5172k Nf4 Rg8 Rg1 Ke7 Rg3 Kd6 Kh2 Rc7 Rg6 
16  <  +1.09   00&#58;02    5704k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Rxg7 
                              Re2+ Kf5 Rf2+ Kg6 Rg2+ Kxh6 Rxg7 Kxg7 Rd8 
16     +1.45   00&#58;02    6097k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rc6+ Rd6 Rxc4 
                              Kd7 Rc2 Re6+ Kf4 Kd6 
17  <  +1.29   00&#58;02    6385k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Nxb6 
                              Rc6 
17     +1.37   00&#58;02    6655k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rxc4 Kd6 Rc8 Rf5 
                              Rg8 
18  <  +1.21   00&#58;02    6882k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rxc4 Kd6 Rc8 Rh5 
                              Rd8+ Ke6 Re8+ Kd6 
18     +1.25   00&#58;02    7494k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rxc4 Kd6 Rc2 Rh5 
                              Rh2 Rf5 Rg2 
19     +1.21   00&#58;02    9068k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rc6+ Rd6 Rxc4 
                              Kd5 Rc8 a5 Kd3 Rg6 Rd8+ Ke6 Ke3 Rg4 Rb8 Kd5 Rxb6 
                              Re4+ Kf3 Rxh4 
20  >  +1.33   00&#58;03   12101k Nf4 Rg8 Rg1 Ke7 Kh2 Kd6 Rfg3 Rc7 Rg6 
20     +1.17   00&#58;03   12927k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rc6+ Rd6 Rxc4 
                              Kd5 Rc8 a5 Kd3 Rg6 Rd8+ Kc6 Rf8 Rg4 h5 Kd5 Rf5+ 
                              Ke6 
21  >  +1.25   00&#58;03   16008k Nf4 Rg8 Rg1 Ke7 Kh2 Kd6 Rfg3 Rc7 Rg6 
21     +1.17   00&#58;04   16992k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rc6+ Rd6 Rxc4 
                              Kd5 Rc8 a5 Kd3 Rg6 Rd8+ Kc6 Rf8 Rg4 h5 Kd5 Rf5+ 
                              Ke6 Re5+ Kd6 Re3 
22  >  +1.25   00&#58;05   25301k Nf4 Rg8 Rg1 Ke7 Kh2 Rcd8 Rfg3 g5 fxg6 Ne4 Rf3 
22  >  +1.33   00&#58;05   30651k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Ke3 
                              Rf5 Rxg7 Rxd5 Rg8+ Ke7 Rxc8 Kxe6 Rc6+ Rd6 Rxc4 
                              Kd5 Rc8 a5 Kd3 Rg6 Rd8+ Kc6 Rf8 Rg4 h5 Kd5 Rf5+ 
                              Ke6 Rf3 
22  >  +1.49   00&#58;06   39069k Nf4 Rg8 Rg1 Rc7 Kh3 Ke7 Rg6 Kd8 Rfg3 Ne4 Nxd5 
                              Nxg3 Kxg3 
22     +1.54   00&#58;13   90787k Nf4 Rg8 Ng6 b5 R3f2 Rb8 Kf3 b4 axb4 Rxb4 Kf4 Kd8 
                              Ra1 Rb6 Rg2 h5 Re2 Ng4 Kg5 Nf6 Rg2 Kc7 
23     +1.54   00&#58;24  181150k Nf4 Rg8 Ng6 Rb8 Rg1 Kd8 Kf2 b5 Ke3 b4 Kf4 bxa3 
                              bxa3 Kc7 Ke5 Rbe8 Nf4 Kc6 Rxg7 Rxg7 Kxf6 Rb7 Ke5 
                              Rb3 Rxb3 cxb3 Nxd5 
24     +1.49   00&#58;26  195038k Nf4 Rg8 Ng6 Kd8 Rg1 b5 Kg3 Re8 Kh3 Rg8 Nf4 Ke8 
                              Rfg3 Rc7 h5 a5 Kh4 Ra7 Rg6 Kf8 R6g2 Ke8 Rg3 b4 
                              Ra1 c3 bxc3 b3 Rb1 a4 Rb2 
25  >  +1.58   00&#58;27  209122k Nf4 Ne4 Nxd5 Nd2 Rg1 Nxf3 Kxf3 Rxf5+ Ke4 Rf2 Rxg7 
                              Re2+ Kf5 Rf2+ Ke5 Re2+ Kd6 Rd8+ Rd7 Rxd7+ exd7+ 
                              Kd8 Nb4 
25  >  +1.66   00&#58;31  237868k Nf4 Ne4 Nxd5 Nd2 Rg1 Rd8 Nc7+ Ke7 Rg3 g5 hxg5 
                              hxg5 Rh3 Rxd4 Rh7+ Kf6 e7 
25     +1.66   00&#58;38  299814k Nf4 Rg8 Ng6 Kd8 Rg1 Re8 Nf4 Re7 Rg3 b5 Kh3 a5 
                              Rxg7 Rxg7 Rxg7 c3 bxc3 Rxc3+ Kg2 Rxa3 Rf7 Ra2+ 
                              Kf3 Ra3+ Ke2 Ra2+ Kd3 Ra3+ Kc2 Rf3 Nxd5 Nxd5 Rd7+ 
                              Ke8 Rxd5 
26  >  +1.86   00&#58;51  400188k Nf4 Ne4 Nxd5 Rd8 e7 Rxd5 exf8=Q+ Kxf8 Rf4 Nd6 a4 
                              Kf7 Kf3 h5 Rg1 b5 Rg5 bxa4 f6 Rxg5 hxg5 g6 Ke3 a3 
                              bxa3 h4 d5 h3 Rf2 
26     +1.90   01&#58;24  672411k Nf4 Rg8 Ng6 Kd8 Rg1 Re8 Nf4 Re7 Rg3 b5 Kh3 Rcc7 
                              Re3 h5 Rg6 b4 axb4 Rb7 Re5 Rb5 Rxf6 gxf6 Rxd5+ 
                              Rxd5 Nxd5 Rb7 Nxf6 Rb5 Nxh5 Rxf5 Kg4 Rf2 
27     +1.82   01&#58;33  739828k Nf4 Rg8 Ng6 Kd8 Rg1 Re8 Nf4 Re7 Rg3 b5 Kh3 Rcc7 
                              Re3 Rc6 Ng6 Ra7 Ne5 Rcc7 e7+ Kxe7 Rxg7+ Kf8 Rg6 
                              Ne4 Rxh6 Rh7 Rb6 Rhb7 Rg6 Rh7 Kg4 Rag7 Rxg7 Rxg7+ 
                              Kf4 
28     +1.86   02&#58;29    1200M Nf4 Ne4 Nxd5 Rd8 e7 Rxd5 exf8=Q+ Kxf8 Rf4 Nd6 a4 
                              Kf7 Kf3 Kf6 Kg4 Kf7 Re1 Ne8 Re5 Nf6+ Kf3 Rd6 d5 
                              Nd7 Ree4 h5 Ke2 Rxd5 Rxc4 Nc5 Rc3 a5 b4 axb4 Rxb4 
                              Re5+ Re3 Rxf5 Rxb6 Nxa4 
29  >  +1.94   02&#58;43    1314M Nf4 Rg8 Ng6 Kd8 Rg1 Rc7 Re3 Re8 Kf3 Rb7 Re2 Kc7 
                              Reg2 Kd6 Ne5 Nh5 Rg6 Ke7 b3 
29  >  +2.02   03&#58;02    1479M Nf4 Rc7 Rg1 Rb7 Ng6 Rg8 Rf2 b5 Kf3 Kd8 Rfg2 b4 
                              axb4 Rxb4 Kf4 Rb3 Ke5 Ke8 Rc2 Kd8 Kd6 
29  <  +1.78   04&#58;16    2090M Nf4 Ne4 Nxd5 Rd8 Nxb6 Nd2 
29     +1.94   04&#58;39    2269M Nf4 Ne4 Nxd5 Rd8 e7 Rxd5 exf8=N Kxf8 Rf4 Nf6 Re1 
                              Rb5 Re2 Kf7 Rff2 h5 a4 Rb4 Re6 Rb3 a5 bxa5 Rxa6 
                              Ng4 Ra7+ Kf6 Rd2 Ne3+ Kf2 Nxf5 Ra6+ Kf7 Rxa5 g6 
                              Ra7+ Kf6 Ra6+ Kf7 Rc6 Rh3 Rxc4 Rh2+ Ke1 Rh1+ Ke2 
                              Rxh4 Rc7+ Ke6 Rc6+ Nd6 
30  <  +1.82   05&#58;19    2614M Nf4 Rg8 Ng6 Kd8 Rg1 Re8 Nf4 Re7 Rg3 b5 Kh3 Rcc7 
30  >  +2.06   05&#58;54    2890M Nf4 Rg8 Ng6 Ne4 Re3 Rd8 Re2 c3 Rc2 Nd2 Rg1 Ne4 
                              bxc3 Nd6 Rf2 Ne4 Rb2 
30     +1.90   07&#58;48    3824M Nf4 Rg8 Ng6 Rc7 Re3 Kd8 Kf3 Kc8 Rg1 Kb7 Re2 Re8 
                              Nf4 Ree7 Rc2 b5 Rcg2 Kb6 Ke3 Kb7 Ng6 Re8 Ne5 Nh5 
                              Kf3 c3 Nd7 Rc4 bxc3 Rxc3+ Kg4 Nf6+ Nxf6 gxf6 Kh5 
                              Kc6 Kxh6 Rxa3 h5 

Nodes&#58; 3825105729
Nodes/second&#58; 8169636
Best move&#58; Nf4
Ponder move&#58; Rg8
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yanquis1972
Posts: 1766
Joined: Wed Jun 03, 2009 12:14 am

Re: Test Position: Poisoned pawn

Post by yanquis1972 »

would you mind seeing how stockfish scores Nxg7?
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zullil
Posts: 6442
Joined: Tue Jan 09, 2007 12:31 am
Location: PA USA
Full name: Louis Zulli

Re: Test Position: Poisoned pawn

Post by zullil »

zullil wrote:
Albert Silver wrote:In the following position, the pawn on g7 was mistakenly taken, and a draw ended up ensuing as the knight found itself prisoner on the square.

[D]2r1kr2/6p1/pp2Pn1p/3p1P1N/2pP3P/P4R2/1P4K1/5R2 w - - 0 37

The correct move is 1.Nf4!
Stockfish-1.7.1 (8 threads) opts for Nf4 very quickly.
Here's Stockfish to depth 30 searching just Nxg7+:

Code: Select all

Searching&#58; 2r1kr2/6p1/pp2Pn1p/3p1P1N/2pP3P/P4R2/1P4K1/5R2 w - -
infinite&#58; 0 ponder&#58; 0 time&#58; 0 increment&#58; 0 moves to go&#58; 0
 2     +0.85   00&#58;01       39 Nxg7+ Ke7 Rg3 
 3     +0.65   00&#58;01      233 Nxg7+ Ke7 Kg3 Rg8 
 4     +0.40   00&#58;01      784 Nxg7+ Ke7 Rg3 Ne4 Rg6 
 5     +0.48   00&#58;01     1133 Nxg7+ Ke7 Rg3 Ne4 Rg6 Rg8 
 6  <  +0.28   00&#58;01     6862 Nxg7+ Ke7 Rg3 Rg8 Rg6 c3 
 6     +0.53   00&#58;01     7377 Nxg7+ Ke7 Rg3 Ne4 Rg6 c3 bxc3 Rxc3 Rb1 
 7  >  +0.61   00&#58;01    10801 Nxg7+ Ke7 Rg3 Ne4 Rg6 c3 bxc3 Rxc3 Nh5 Rxa3 Rg7+ 
 7  <  +0.44   00&#58;01    11073 Nxg7+ Ke7 Rg3 Ne4 Rg6 c3 bxc3 Rxc3 Nh5 Rxa3 Rg7+ 
 7  >  +0.69   00&#58;01    12195 Nxg7+ Ke7 Rg3 Ne4 Rg6 c3 bxc3 Rxc3 a4 
 7     +0.40   00&#58;01    12545 Nxg7+ Ke7 Rg3 Ne4 Rg6 c3 bxc3 Rxc3 a4 
 8  >  +0.57   00&#58;01    16678 Nxg7+ Ke7 Rg3 Ne4 Rg6 c3 bxc3 Rxc3 a4 
 8     +0.69   00&#58;01    20222 Nxg7+ Ke7 Rg3 Ne4 Rg6 c3 bxc3 Rxc3 Nh5 Rc2+ Kh3 
                              Nf2+ Kg3 Rxf5 Rxh6 
 9     +0.69   00&#58;01   211050 Nxg7+ Ke7 Rg1 Rg8 Kh3 b5 Rg6 Rcf8 Rf1 Nh5 Kg4 
                              Nf6+ Kf3 Ne4 
10     +0.73   00&#58;01   236626 Nxg7+ Ke7 Rg1 Ne4 Re3 Nd6 Re5 c3 bxc3 Rxc3 Rxd5 
                              Rxa3 
11  >  +0.81   00&#58;01   277063 Nxg7+ Ke7 Rg3 Rg8 Rg6 c3 bxc3 Rxc3 Rb1 b5 a4 Rc2+ 
                              Kf3 bxa4 Rb7+ 
11  <  +0.65   00&#58;01   298669 Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Kg3 
                              Rxd4 Rxh6 Ne4+ 
11     +0.69   00&#58;01   354521 Nxg7+ Ke7 Rg1 Ne4 Kh3 Nd2 Rfg3 Ne4 R3g2 c3 Rc2 
                              Nd6 Rxc3 Rxc3+ bxc3 Nxf5 Nxf5+ Rxf5 
12  >  +0.77   00&#58;01   381616 Nxg7+ Ke7 Rg1 Ne4 Kh3 Nd2 Rfg3 Ne4 Rg6 h5 R6g2 c3 
                              Rc2 cxb2 Rxb2 
12     +0.77   00&#58;01   388648 Nxg7+ Ke7 Kh3 Ne4 Rg1 Nd2 Rfg3 Ne4 Rg6 Rf6 R6g2 
                              c3 bxc3 Rxc3+ Kg4 Rxa3 
13  >  +0.89   00&#58;01   512443 Nxg7+ Ke7 Kh3 Ne4 Rg1 Nd2 Re3 Nb3 Rd1 Rg8 Nh5 
13  >  +1.01   00&#58;01   838119 Nxg7+ Ke7 Rg1 Ne4 Kh3 Nd2 Re3 Nb3 Rd1 Rg8 Nh5 
13  <  +0.65   00&#58;01    1064k Nxg7+ Ke7 Rg1 Ne4 Kh3 Rg8 Rg6 Rcf8 Kg4 Rf6 Kh5 
                              Rff8 Re3 Rf6 Rg2 Kf8 
13  <  +0.53   00&#58;01    1345k Nxg7+ Ke7 Rg1 Ne4 Kh3 Rg8 Rg6 Rcf8 Kg4 Rf6 Kh5 
                              Rgf8 Rxh6 Rg8 Rg6 Rh8+ Kg4 Rg8 
13     +0.81   00&#58;01    1409k Nxg7+ Ke7 Rg1 Ne4 Kh3 Rg8 Rg6 Rcf8 Kg4 Rf6 Kh5 
                              Rgf8 Re3 Rxg6 Kxg6 Rf6+ Kh7 b5 Rf3 Nd2 Rg3 Nb3 
                              Rg6 Rf8 
14  >  +0.89   00&#58;01    1674k Nxg7+ Ke7 Rg1 Ne4 Kh3 Rg8 Rg6 Rcf8 Kg4 Rf6 Kh5 
                              Rgf8 Re3 Rxg6 Kxg6 Rf6+ Kh7 b5 Rf3 Nd2 Rg3 Nb3 
                              Rg6 Rf8 Rg4 
14     +0.93   00&#58;01    1719k Nxg7+ Ke7 Rg1 Ne4 Kh3 Rg8 Rg6 Rcf8 Kg4 Rf6 Kh5 
                              Rgf8 Re3 Rxg6 Kxg6 Rf6+ Kh7 b5 Re2 a5 Rg2 b4 axb4 
                              axb4 
15     +0.85   00&#58;01    2234k Nxg7+ Ke7 Rg1 Rg8 Kh3 b5 Rg6 Rcf8 Kg3 Kd6 Kf2 
                              Ne4+ Ke3 Rf6 Rxf6 Nxf6 Rg3 Ne4 Rg1 Ke7 
16  >  +1.01   00&#58;01    2375k Nxg7+ Ke7 Rg1 Rg8 Kh3 b5 Rg6 Rcf8 Kg3 Kd6 Kf2 
                              Ne4+ Ke3 Rf6 Rxf6 Nxf6 Rg3 Ne4 Rg1 Ke7 Kf4 
16     +1.01   00&#58;01    2585k Nxg7+ Ke7 Rg1 Rg8 Kh3 Ra8 Rg6 Raf8 Kg3 Kd6 Kf2 
                              Ne4+ Ke3 Ke7 Rg1 a5 Rff1 b5 Kf4 
17  <  +0.81   00&#58;01    4224k Nxg7+ Ke7 Rg1 Rc7 Re3 Rfc8 Kf3 c3 bxc3 Rxc3 Kf4 
                              Rxe3 Kxe3 Rc3+ 
17     +0.81   00&#58;02    5668k Nxg7+ Ke7 Rg1 Rc7 Kg3 Rg8 Kh3 c3 Rxc3 Rxc3+ bxc3 
                              Rc8 Rg3 a5 Kh2 Ne4 Rf3 Rg8 Nh5 Rc8 Kh3 
18     +0.97   00&#58;02   10121k Nxg7+ Ke7 Rg1 Rc7 Kg3 Rg8 Kh2 Rgc8 Rc3 b5 Rg6 b4 
                              axb4 Rb7 Kg3 Rxb4 Ra3 Rxb2 Rxa6 Rcb8 Kf4 Rf2+ Ke5 
                              Re2+ Kf4 
19     +0.89   00&#58;03   13391k Nxg7+ Ke7 Rg1 Rc7 Kh3 Rfc8 Rc3 a5 Rg6 b5 Kg3 b4 
                              axb4 axb4 Rc2 c3 b3 Ra7 Kf4 Rg8 Ke5 h5 
20  >  +1.05   00&#58;03   18950k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rg8 Kf3 Ne4 Rg6 
20     +1.17   00&#58;04   22644k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rfc8 Rc1 b5 Rg6 c3 bxc3 h5 
                              Kf3 Rxc3+ Rxc3 Rxc3+ Kf4 Rd3 Kg5 Rg3+ Kh6 Rf3 
                              Nxh5 Nxh5 Kxh5 Rxf5+ Kg4 Rf6 Rxf6 Kxf6 h5 Kxe6 
21  <  +0.85   00&#58;05   27472k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rfc8 Rc1 b5 Rg6 b4 axb4 Rb7 
                              Rxh6 Rg8 Rg6 Rxb4 Kf3 Rxb2 Ra1 Rgb8 Rxa6 R8b3+ 
                              Kf4 Rf2+ Kg5 Rg3+ Kh6 Ng8+ Kh7 Nf6+ 
21     +0.65   00&#58;08   58851k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rfc8 Rc1 b5 Rg6 b4 axb4 Rb7 
                              Rxh6 Rg8 Rg6 Rxb4 Kf3 Rxb2 Ra1 Rgb8 Rgg1 R8b3+ 
                              Kf4 Rd3 Rxa6 Rxd4+ Kg5 Nh7+ Kg6 Nf8+ Kh5 c3 Ra7+ 
                              Kf6 
22     +0.89   00&#58;11   76130k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rfc8 Rc1 b5 Rg6 b4 axb4 Rb7 
                              Kf3 Rxb4 Rxh6 Rb3+ Rc3 Rxb2 Nh5 Nxh5 Rxh5 Kf6 Kf4 
                              Rf2+ Rf3 Rxf3+ Kxf3 c3 Kf4 a5 Rh6+ Ke7 Rh7+ Kf6 
23     +0.93   00&#58;13   94923k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rfc8 Rc1 b5 Rg6 b4 axb4 Rb7 
                              Kf3 Rxb4 Rxh6 Rb3+ Rc3 Rxb2 Nh5 Ne4 Rh7+ Kd6 Rd7+ 
                              Kc6 Rxc4+ dxc4 Kxe4 c3 Nf4 c2 d5+ Kb6 Ne2 Rb4+ 
                              Kd3 Rf4 Rf7 Rxh4 d6 c1=Q Nxc1 Rxc1 
24  <  +0.77   00&#58;14  104045k Nxg7+ Ke7 Kh3 Rc7 Rg3 Rfc8 Rff3 b5 Rg6 c3 bxc3 
                              Rxc3 Kg3 a5 Rxh6 b4 axb4 axb4 Kf4 Rxf3+ Kxf3 b3 
                              Kf4 b2 
24     +0.77   00&#58;15  107138k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rfc8 Rc1 b5 Rg6 b4 axb4 Rb7 
                              Kf3 Rxb4 Rxh6 Rb3+ Rc3 Rxb2 Nh5 Ne4 Rh7+ Kd6 Rd7+ 
                              Kc6 Rxc4+ dxc4 Kxe4 c3 Nf4 c2 d5+ Kb6 Ne2 Rb4+ 
                              Kd3 Rb3+ Kd2 Rf3 f6 Rxf6 Nc1 Rf2+ Ke3 Rf1 
25     +0.73   00&#58;19  140209k Nxg7+ Ke7 Rg1 Rc7 Rg3 Rfc8 Rc1 b5 Rg6 b4 axb4 Rb7 
                              Kf3 Rxb4 Rxh6 Rb3+ Rc3 Rxb2 Nh5 Ne4 Rh7+ Kd6 Rd7+ 
                              Kc6 Rxc4+ dxc4 Kxe4 c3 Nf4 c2 d5+ Kb6 Ne2 Rb4+ 
                              Kd3 Rb3+ Kd4 Rb4+ Ke5 Rcc4 Nc1 Re4+ Kd6 Rb1 Nd3 
                              Kb5 e7 
26  >  +0.85   00&#58;22  166787k Nxg7+ Ke7 Rg1 Rc7 Rg3 Ne4 Rg6 c3 Rc1 c2 Kf3 Nd2+ 
                              Ke3 Nc4+ Ke2 Nd6 Rxh6 Nxf5 Nxf5+ Rxf5 Rg6 
26  <  +0.61   00&#58;30  233457k Nxg7+ Ke7 Kh3 b5 Rg1 b4 axb4 Rb8 b5 Rxb5 Rg2 Rfb8 
26     +0.61   00&#58;39  307683k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rxh6 
                              Rxd4 Kh3 Re4 Nh5 Nxh5 Rxh5 Rxe6 Rh7+ Kd6 Ra7 Ref6 
                              Rxa6+ Ke5 Rxf6 Kxf6 Rb3 Ke5 Rxb5 Rxf5 Kg4 Rf4+ 
                              Kg5 Rf3 a4 Rg3+ Kh5 Ra3 
27  >  +0.77   00&#58;45  351564k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rxh6 
                              Rxd4 Kh3 Re4 Nh5 Nxh5 Rxh5 Rxe6 Rh7+ Kd6 h5 Ref6 
                              Kg4 Ke5 h6 Kd4 Kg5 Ke4 Rf4+ Ke5 Re7+ 
27     +0.77   00&#58;45  356629k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rxh6 
                              Rxd4 Kh3 Re4 Nh5 Nxh5 Rxh5 Rxe6 Rh7+ Kd6 h5 Ref6 
                              Kg4 Rg8+ Kf4 Rgf8 Kg5 a5 h6 b4 axb4 axb4 Ra7 Ke5 
                              Re7+ Kd4 Rf4+ Kc5 
28  >  +1.01   01&#58;10  558617k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rxh6 
                              Rxd4 Kh3 Re4 Nh5 Nxh5 Rxh5 Rxe6 Rh7+ Kd6 h5 Ref6 
                              Kg4 Rg8+ Kf4 Rgf8 Kg5 a5 h6 b4 Rb7 Ke5 h7 Rxf5+ 
                              Rxf5+ Rxf5+ Kg6 Rf6+ Kg7 
28  <  +0.53   01&#58;14  594427k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rxh6 
                              Rxd4 Kh3 Re4 Nh5 Nxh5 Rxh5 Rxe6 Rh7+ Kd6 h5 Re5 
                              Rh6+ Kc5 Kg4 d4 Rxa6 Rd5 h6 d3 Rf1 d2 Rd1 Rfxf5 
                              Rxd2 Rg5+ Kf4 Rgf5+ Ke4 Rfe5+ Kf4 Rf5+ 
28     +0.93   01&#58;25  677880k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rd3 
                              Rc2+ Kf3 Rg8 Kf4 Rf2+ Rf3 Rd2 Re3 Rxd4+ Ke5 Rxh4 
                              Rxf6 Rxg7 Rc3 Re4+ Kxd5 Kxf6 Kxe4 Rg1 Kd5 Rd1+ 
                              Kc6 Re1 Rf3 h5 Kb7 h4 Kxa6 Re5 Kb6 Ke7 Kc6 
29     +0.85   01&#58;39  795633k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rd3 
                              Rc2+ Kf3 Rh2 Kg3 Rh1 Kg2 Rc1 Rxh6 Rfc8 Nh5 R8c2+ 
                              Kg3 Rg1+ Kf4 Rf2+ Rf3 Rg4+ Ke3 Ra2 Nxf6 Rxa3+ Ke2 
                              Ra2+ Ke1 Rg1+ Rf1 Ra1+ Ke2 Rgxf1 Nxd5+ Kd6 e7+ 
                              Kd7 Rh8 Rae1+ Kd2 Rxe7 Nxe7 Kxe7 Rh7+ 
30  >  +1.01   01&#58;59  957582k Nxg7+ Ke7 Rg3 b5 Rg6 c3 bxc3 Rxc3 Rf3 Rc4 Rd3 
                              Rc2+ Kf3 Rh2 Kg3 Rh1 Kg2 Rc1 Rxh6 Ne4 Rf3 Rc2+ 
                              Kh3 Rc4 Nh5 Rxd4 Rh7+ 
30  <  +0.69   03&#58;11    1548M Nxg7+ Ke7 Rg1 Ne4 Kh3 Nd2 Re3 Ne4 Kg4 Nf2+ Kf3 
                              Nd3 Rg6 Nxb2 Re5 Rf6 Rxf6 Kxf6 Nh5+ Ke7 f6+ 
30  >  +1.17   03&#58;17    1598M Nxg7+ Ke7 Rg3 Rg8 Rg1 b5 Kf3 Ne4 Rg6 c3 bxc3 
                              Rxc3+ Kf4 Rxa3 Rxh6 b4 Rgg6 a5 f6+ Nxf6 Nf5+ 
30     +0.93   03&#58;22    1634M Nxg7+ Ke7 Rg3 Rg8 Rg1 b5 Kf3 c3 bxc3 Rxc3+ Kf4 
                              Rxg3 Rxg3 Rc8 Rg6 Rc1 Rxh6 Rf1+ Ke3 Rg1 Rg6 Re1+ 
                              Kf3 Rd1 Rxf6 Kxf6 Nh5+ Ke7 Kf4 Kd6 Kg5 Rxd4 Nf4 
                              Ra4 h5 Rxa3 f6 Rg3+ Kf5 d4 h6 a5 

Nodes&#58; 1634715303
Nodes/second&#58; 8085525
Best move&#58; Nxg7+
Ponder move&#58; Ke7
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zullil
Posts: 6442
Joined: Tue Jan 09, 2007 12:31 am
Location: PA USA
Full name: Louis Zulli

Re: Test Position: Poisoned pawn

Post by zullil »

yanquis1972 wrote:would you mind seeing how stockfish scores Nxg7?
Was working on that when you posted! :D
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Albert Silver
Posts: 3019
Joined: Wed Mar 08, 2006 9:57 pm
Location: Rio de Janeiro, Brazil

Re: Test Position: Poisoned pawn

Post by Albert Silver »

yanquis1972 wrote:at d25 rybka seems to agree with the conclusion but disagree that Nxg7 draws (in fact she goes so far as to evaluate on the cusp of +/-)

Analysis by Deep Rybka 4 x64 AN:

1. +/- (1.21): 1.Nf4 Rg8
2. +/- (0.73): 1.Nxg7+ Ke7 2.Rg3 b5 3.Rg6 c3 4.bxc3 Rxc3 5.Rf3 Rc4 6.Rd3 Rc2+ 7.Kh3 h5 8.Rb3 Rfc8 9.Rg5 R8c3+ 10.Rxc3 Rxc3+ 11.Kg2 Re3 12.Nxh5 Nxh5 13.Rxh5 Kf6 14.Rg5 a5 15.Rg3 Re4 16.Rf3
3. +/= (0.42): 1.Nxf6+ Rxf6 2.Rg3 Rc7 3.Kh3 b5 4.Kg4 Ke7
What is AN?

BTW, I took this from a match between Houdini and DR4, and it drew. The game left Houdini's knight stuck on g7 forever, and neither seemed to find a way to safely untangle the position. I looked it over and if there is a way out it is subtle.
"Tactics are the bricks and sticks that make up a game, but positional play is the architectural blueprint."
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yanquis1972
Posts: 1766
Joined: Wed Jun 03, 2009 12:14 am

Re: Test Position: Poisoned pawn

Post by yanquis1972 »

AN is just my chessbase engine for analysis; it's got large pages & always score main move ticked & RES @ 60.

so stockfish's eval is similar to rybka's...i'll let rybka do a deeper search to see if it starts dropping.
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Albert Silver
Posts: 3019
Joined: Wed Mar 08, 2006 9:57 pm
Location: Rio de Janeiro, Brazil

Re: Test Position: Poisoned pawn

Post by Albert Silver »

yanquis1972 wrote:AN is just my chessbase engine for analysis; it's got large pages & always score main move ticked & RES @ 60.

so stockfish's eval is similar to rybka's...i'll let rybka do a deeper search to see if it starts dropping.
Be warned that Vas said during testing that Score Main Move gave a slight but consistent performance hit in match play. Not sure about analysis.

As to the Large Pages, I presume you know the proper way to set them up, and that they can only be used once per boot.
"Tactics are the bricks and sticks that make up a game, but positional play is the architectural blueprint."
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