Test Position: 1.Nd6+!!

acase · Post by **acase** » Thu Feb 25, 2010 7:43 pm

This is a position that is a modification of a test position that was posted earlier by Jon Dart (see here: http://talkchess.com/forum/viewtopic.php?t=32422), hopefully nobody accuses me of cloning positions

.
Most programs seem to like 1.Nxb6 (the black Knight at b6 was puit there as a decoy and it seems to work beatifully as most of the programs like to exchange the Knights there), however 1.Nd6+!! is much better.
The idea behind the Knight sacrifice is to draw the Bishop from the e7 square so it cannot block the f file from the f6 square.
There are a lot of subtle tactics in this position that nust be calculated in order for a peogram to see the correct move and not be lured to the much inferior 1.Nxb6. A hat tip to Jon Dart for the original position.

As usual this is a pretty tough position for most programs (although of course there might be one out there that finds it quickly).

The main line goes like this:

1. Nd6+!! Bxd6 2. Bxf7+ Kxf7 3. Nxf4 Bxf4 4. Bxf4 Kg8 5. Bh6!! d6 6.Qh5

[d] rnbqk2r/pp1pbppp/1np5/8/2NP1p2/P6N/B2B2PP/R2Q1RK1 w kq - 0 1[/url]

jdart · Post by **jdart** » Thu Feb 25, 2010 8:33 pm

Arasan 11.7 didn't get this even after 15 minutes search on a quad (Q6600). It prefers Nxb6.

--Jon

gordonr · Post by **gordonr** » Thu Feb 25, 2010 10:11 pm

Q9300 @ 2.5GHz, 1 GB hash

Analysis by spark-0.3a:

...
7.Nxc4 dxc4 8.Be3
-+ (-1.99) Depth: 14/28 00:00:01 7357kN
1.Ne5
-+ (-1.74) Depth: 15/30 00:00:05 30886kN
1.Ne5 d5 2.Qh5 0-0 3.Bb1 f5 4.Rxf4 Nc4 5.Rxf5 g6 6.Rxf8+ Qxf8 7.Nxg6 hxg6 8.Bxg6 Qg7
-+ (-1.77) Depth: 15/30 00:00:05 33003kN
1.Ne5 d5 2.Qh5 0-0 3.Bb1 f5 4.Rxf4 Nc4 5.Rxf5 g6 6.Rxf8+ Qxf8 7.Bxg6 hxg6 8.Qxg6+ Qg7 9.Qe8+ Bf8 10.Qxc8 Nxd2 11.Nf4
-+ (-1.61) Depth: 16/31 00:00:11 68677kN
1.Nxb6
-/+ (-1.36) Depth: 17/38 00:00:48 301mN
1.Nxb6
-/+ (-0.86) Depth: 17/40 00:00:50 313mN
1.Nxb6 axb6 2.Bxf7+ Kxf7 3.Bxf4 Bf6 4.Ng5+ Kg8 5.Bd6 Ra5 6.Ne4 Na6 7.Qb3+ Rd5 8.Nxf6+ gxf6 9.Be5 Kf7 10.Rxf6+ Qxf6 11.Bxf6 Kxf6 12.Rf1+ Ke7 13.Qf3 Rd6 14.Qf5
-/+ (-0.86) Depth: 17/40 00:00:52 326mN
1.Nxb6 axb6 2.Bxf7+ Kxf7 3.Bxf4 Bf6 4.Ng5+ Kg8 5.Bd6 Ra5 6.Ne4 Rd5 7.Nxf6+ gxf6 8.Bxb8 d6 9.Qd3 Rg5 10.Rf2 Kg7 11.Raf1 Be6
-/+ (-0.87) Depth: 18/40 00:01:03 397mN
1.Nxb6 axb6 2.Bxf7+ Kxf7 3.Bxf4 Bf6 4.Ng5+ Kg8 5.Bd6 Ra5 6.Ne4 Rd5 7.Nxf6+ gxf6 8.Bxb8 d6 9.Qd3 Rg5 10.Rf2 Kg7 11.Raf1 Be6 12.Qe4
-/+ (-0.99) Depth: 19/46 00:01:38 634mN
1.Nxb6
-/+ (-0.74) Depth: 20/46 00:02:40 1039mN
1.Nxb6
= (-0.24) Depth: 20/46 00:02:45 1064mN
1.Nxb6
+/= (0.51) Depth: 20/47 00:03:31 1342mN
1.Nxb6 axb6 2.Bxf7+ Kxf7 3.Nxf4 Bf6 4.Nh5 Rf8 5.Qg4 Rg8 6.Qf5 d6 7.Qxh7 Nd7 8.Bg5 Nf8 9.Bxf6 Nxh7 10.Bxd8+ Kg6 11.Nf4+ Kh6 12.Bxb6 Bf5
= (0.14) Depth: 20/47 00:03:40 1397mN
1.Nxb6 axb6 2.Bxf7+ Kxf7 3.Nxf4 Bf6 4.Nh5 Rf8 5.Qg4 Rg8 6.Qf5 d6 7.Qxh7 Nd7 8.Bg5 Nf8 9.Bxf6 Nxh7 10.Bxd8+ Kg6 11.Nf4+ Kh6 12.Bxb6 Nf6 13.Rfe1
+/= (0.30) Depth: 21/54 00:05:41 2169mN
1.Nxb6
+/= (0.55) Depth: 22/67 00:07:57 3024mN
1.Nxb6 axb6 2.Bxf7+ Kxf7 3.Nxf4 Bf6 4.Nh5 Rf8 5.Bg5 d5 6.Bxf6 gxf6 7.Rxf6+ Kg8 8.Qf3 Rxf6 9.Nxf6+ Kh8 10.Re1 Rxa3 11.Qxa3 Qxf6 12.Re8+ Kg7 13.Qe3 Bf5 14.Rxb8 Qf7 15.Qg5+ Bg6 16.Qe5+ Kh6 17.g4
+/= (0.42) Depth: 22/67 00:09:18 3547mN
1.Nxb6
+/= (0.67) Depth: 23/68 00:16:36 6374mN
1.Nxb6 Qxb6 2.Bxf7+ Kd8 3.Bxf4 d6 4.Bg5 Bxg5 5.Nxg5 Rf8 6.Nxh7 Rh8 7.Bg6 Nd7 8.Ng5 Kc7 9.Rf7 Kb8 10.Rxg7 Qb2 11.Ne4 d5 12.Nd6 Rh6 13.h3 Nc5
+/- (0.71) Depth: 23/68 00:24:59 9599mN
1.Nxb6 Qxb6 2.Bxf7+ Kd8 3.Bxf4 Bf6 4.Bg5 Kc7 5.Bxf6 gxf6 6.Rxf6 Na6 7.Rb1 Qa5 8.Qc1 b6 9.Ng5 Kb8 10.Ne4 Bb7 11.Bc4 Nc7 12.Rf7 d5 13.Qf4 b5 14.Rf8+ Rxf8 15.Qxf8+ Bc8 16.Nd6 Qa6
+/- (0.90) Depth: 24/70 00:39:55 15526mN
1.Nd6+
+/- (0.96) Depth: 24/70 00:46:01 18039mN
1.Nd6+
+- (1.46) Depth: 24/70 00:47:03 18431mN

zullil · Post by **zullil** » Fri Feb 26, 2010 6:10 am

acase wrote: [d] rnbqk2r/pp1pbppp/1np5/8/2NP1p2/P6N/B2B2PP/R2Q1RK1 w kq - 0 1

Stockfish-1.6.3 (8 threads) is quite happy with Nxb6. I'll try a deeper search, but it may take a while.

Code: Select all

Searching: rnbqk2r/pp1pbppp/1np5/8/2NP1p2/P6N/B2B2PP/R2Q1RK1 w kq -
infinite: 0 ponder: 0 time: 0 increment: 0 moves to go: 0
 2     -1.98   00:02      501 Rxf4 O-O 
 2     -1.78   00:02      571 Nxf4 O-O 
 2     -1.17   00:02      781 Nxb6 axb6 Rxf4 
 3     -1.98   00:02     2260 Nxb6 axb6 Qg4 g5 
 3     -1.54   00:02     2448 Nxf4 O-O Nh5 
 3     -1.29   00:02     2604 Rxf4 O-O Ne5 
 4     -1.54   00:02     4124 Rxf4 O-O Nxb6 axb6 Qh5 
 5     -1.62   00:02     6748 Rxf4 O-O Ne5 d5 Qh5 
 5     -1.17   00:02     8130 Qg4 g5 Ne5 d5 Qh5 
 6     -1.82   00:02    16636 Qg4 O-O Nxb6 axb6 Qxf4 d5 Bb1 
 7  <  -3.47   00:02    29890 Qg4 O-O Ne5 d5 Qxf4 f6 
 7     -1.54   00:02    33336 Ne5 O-O Rxf4 d5 Qh5 f5 Rf3 
 8     -1.54   00:02    43788 Ne5 O-O Qh5 d5 Nxf4 g6 Qh6 Nc4 Bxc4 dxc4 
 9  <  -1.82   00:02    75305 Ne5 O-O Qh5 d5 Nxf4 g6 Qh6 Bg5 
10     -1.86   00:02   241227 Ne5 O-O Qh5 d5 Bb1 g6 Qh6 Bxh3 Qxh3 Qc8 Qh6 
11     -2.30   00:02   556005 Ne5 O-O Rxf4 d5 Qh5 g6 Qh6 N6d7 Nxd7 Nxd7 Rf3 f5 
12     -2.14   00:03    1421k Ne5 O-O Rxf4 d5 Qh5 g6 Qh6 N6d7 Nxd7 Nxd7 Rf3 f5 
                              Kh1 Nf6 Ng5 
13     -2.42   00:03    4309k Ne5 O-O Nxf4 d5 Qc2 N8d7 Bb1 g6 Ng4 Nf6 Nh6+ Kh8 
                              Ne2 Nc4 
14     -2.59   00:04    9190k Ne5 O-O Nxf4 d5 Qc2 N8d7 Bb1 g6 Ng4 Bg5 Bb4 Nc4 
                              g3 Qb6 Qf2 f5 Bxf8 Nxf8 
14  >  -1.70   00:05   14566k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Kg8 Qh5 Bxa3 Rae1 
15     +0.00   00:06   24219k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Kg8 Qh5 h6 Nd5 cxd5 
                              Qxd5+ Kh7 Qf5+ Kg8 Qd5+ Kh7 
16     +0.00   00:07   32971k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Kg8 Qh5 h6 Nd5 cxd5 
                              Qxd5+ Kh7 Qf5+ Kg8 Qd5+ Kh7 
17     +0.00   00:09   46530k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Qh7+ Rg7 
18     +0.00   00:12   72615k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Qh7+ Rg7 
19     +0.00   00:15   96216k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Qh7+ Rg7 
20     +0.00   00:27  191448k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Qh7+ Rg7 
21  >  +0.20   00:44  327990k Nxb6 Qxb6 Bxf7+ Kxf7 Rxf4+ Kg8 Qe2 Qd8 Re1 g5 Re4 
                              Bf8 Bxg5 Qa5 Re8 Qc7 Qe7 
22     +0.20   01:04  493221k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Rf3 d6 Rg3 
                              Qg8 Re1 Nd7 Rxg6 Qxg6 Re7+ Kxe7 Qxg6 Rxa3 Qe4+ 
                              Kf7 Kf2 
23  >  +1.01   03:44    1762M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Rf3 d6 Rg3 
                              Qg8 Re1 Nd7 Bb4 c5 Qd5+ Kf8 Qxd6+ Kg7 Re7+ 
24     +1.25   07:33    3526M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Rf3 d6 Rg3 
                              Qg8 Re1 Nd7 Rxg6 Qxg6 Re7+ Kxe7 Qxg6 Rxa3 Qe4+ 
                              Kd8 Qe6 Kc7 Bf4 Ne5 Qe7+ Bd7 dxe5 Ra1+ Kf2 Ra2+ 
                              Kf3 fxe5 Bh6 b5 h4 Ra4 
25     +1.78   31:35   14791M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ d5 Qg3 
                              Rg8 Qxb8 Kg6 Nxf6 gxf6 Qf4 Ra4 Qh6+ Kf7 Rae1 Bd7 
                              Bb4 Rxb4 axb4 Rg7 Re5 b5 g3 Bg4 Re3 Kg8 Rxf6 Bd7 
                              Re5 Bg4 Kf2 Qd7 Kg1 
26     +1.98 1:51:39   51568M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ d5 Qg3 
                              Rg8 Qxb8 Kg6 Nxf6 gxf6 Qf4 Ra4 Qh6+ Kf7 Rae1 Bd7 
                              Bb4 Rxb4 axb4 Rg7 Re5 Kg8 Rxf6 Be8 b5 cxb5 Rxb6 
                              Rg6 Rxg6+ Bxg6 Qg5 Qxg5 Rxg5 b4 Kf2 b3 Rxd5 
Nodes: 60224935859
Nodes/second: 7708487
Best move: Nxb6
Ponder move: axb6

Jouni · Post by **Jouni** » Fri Feb 26, 2010 9:46 am

In tactics Stockfish is definitely worse than spark. Spark is so stunningly good, that in my test about mate solving it was equal to Chest!

Jouni

yanquis1972 · Post by **yanquis1972** » Fri Feb 26, 2010 4:54 pm

well, one could also argue that a possible problem with this position is Nxb6 is also a very good & possibly winning move...even if Nd6 is better.

meschle · Post by **meschle** » Fri Feb 26, 2010 9:45 pm

Rybka winfinder in multipv mode finds it quickly

FEN: rnbqk2r/pp1pbppp/1np5/8/2NP1p2/P6N/B2B2PP/R2Q1RK1 w kq - 0 1

Rybka WinFinder v2.2.mp.x64:
4 00:00 1.936 1.982.464 -0.87 Nc4xb6 a7xb6
4 00:00 1.808 1.851.392 -0.12 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
---------------------------------------------------------------------------
5 00:00 4.252 4.354.048 -0.87 Nc4xb6 a7xb6
5 00:00 3.936 4.030.464 -0.87 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
---------------------------------------------------------------------------
6 00:00 6.828 436.992 -0.81 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
6 00:00 19.060 609.920 -0.68 Nh3xf4 d7d5 Nc4e3 OO Qd1b3 Nb8a6 a3a4 Rf8e8 a4a5 Nb6d7 Ne3f5 Nd7f6
---------------------------------------------------------------------------
7 00:00 27.324 444.123 -0.87 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
7 00:00 22.004 479.406 -0.81 Nh3xf4 d7d5 Nc4e3 OO Qd1b3 Nb8a6 a3a4 Rf8e8 a4a5 Nb6d7 Ne3f5 Nd7f6
---------------------------------------------------------------------------
8 00:00 31.420 510.699 -0.93 Nh3xf4 d7d5 Nc4e3 OO Qd1b3 Nb8a6 a3a4 Rf8e8 a4a5 Nb6d7 Ne3f5 Nd7f6
8 00:00 41.648 453.697 -0.81 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
---------------------------------------------------------------------------
9 00:00 249.084 495.266 -0.93 Nh3xf4 d7d5 Nc4e3 OO Qd1b3 Nb8a6 a3a4 Rf8e8 a4a5 Nb6d7 Ne3f5 Nd7f6
9 00:00 246.616 490.358 -0.93 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
---------------------------------------------------------------------------
10 00:01 507.332 504.376 -0.87 Nh3xf4 d7d5 Nc4e3 OO Qd1b3 Nb8a6 a3a4 Rf8e8 a4a5 Nb6d7 Ne3f5 Nd7f6
10 00:01 483.184 511.136 -0.87 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
---------------------------------------------------------------------------
11 00:01 580.416 482.032 -0.87 Nh3xf4 d7d5 Nc4e3 OO Qd1b3 Nb8a6 a3a4 Rf8e8 a4a5 Nb6d7 Ne3f5 Nd7f6
11 00:01 562.936 492.268 -0.87 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
---------------------------------------------------------------------------
12 00:03 672.456 469.389 -0.93 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
12 00:03 1.565.128 508.467 -0.90 Nc4d6+ Be7xd6 Ba2xf7+ Ke8xf7 Nh3xf4 Bd6xf4 Bd2xf4 Kf7g8 Qd1h5 d7d5 Bf4g5 Qd8d7 Ra1e1 g7g6
---------------------------------------------------------------------------
13 00:06 2.886.792 471.312 -0.93 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
13 00:06 2.303.776 483.019 -0.56 Nc4d6+ Be7xd6 Ba2xf7+ Ke8xf7 Nh3xf4 Bd6xf4 Bd2xf4 Kf7g8 Qd1h5 d7d5 Bf4g5 Qd8d7 Ra1e1 h7h6
---------------------------------------------------------------------------
14 00:12 5.970.244 477.321 -0.93 Nc4e5 d7d5 Rf1xf4 OO Qd1h5 g7g6 Qh5h6 Be7f6 Bd2b4 Bf6g7 Qh6h4 Qd8xh4
14 00:12 4.975.548 497.069 -0.31 Nc4d6+ Be7xd6 Ba2xf7+ Ke8xf7 Nh3xf4 Bd6xf4 Bd2xf4 Kf7g8 Qd1h5 h7h6 Ra1e1 d7d5 Re1e8+ Qd8xe8
---------------------------------------------------------------------------
15 00:39 19.191.076 494.580 -0.90 Nh3xf4 d7d5 Nc4e3 OO Qd1b3 Nb8a6 Ra1e1 Qd8d6 a3a4 Be7g5 g2g3 c6c5 a4a5
15 00:39 16.106.184 503.195 +0.18 Nc4d6+ Be7xd6 Ba2xf7+ Ke8xf7 Nh3xf4 Bd6xf4 Bd2xf4 Kf7g8 Qd1h5 h7h6 Ra1e1 d7d5 Re1e8+ Qd8xe8
---------------------------------------------------------------------------
16 02:39 75.694.196 487.547 -0.31 Nc4xb6 a7xb6 Ba2xf7+ Ke8xf7 Nh3xf4 Be7f6 Nf4h5 Rh8f8 Bd2g5 d7d5 Nh5xf6 g7xf6 Bg5xf6 Qd8e8
16 02:38 38.180.296 479.554 +0.18 Nc4d6+ Be7xd6 Ba2xf7+ Ke8xf7 Nh3xf4 Bd6xf4 Bd2xf4 Kf7g8 Qd1h5 h7h6 Ra1e1 d7d5 Re1e8+ Qd8xe8
---------------------------------------------------------------------------
17 03:57 115.150.476 497.238 -0.25 Nc4xb6 a7xb6 Ba2xf7+ Ke8xf7 Nh3xf4 Be7f6 Nf4h5 Rh8f8 Bd2g5 d7d5 Nh5xf6 g7xf6 Bg5xf6 Qd8e8
17 03:57 104.711.460 494.945 +0.18 Nc4d6+ Be7xd6 Ba2xf7+ Ke8xf7 Nh3xf4 Bd6xf4 Bd2xf4 Kf7g8 Qd1h5 h7h6 Ra1e1 d7d5 Re1e8+ Qd8xe8

zullil · Post by **zullil** » Fri Feb 26, 2010 10:11 pm

zullil wrote:
acase wrote: [d] rnbqk2r/pp1pbppp/1np5/8/2NP1p2/P6N/B2B2PP/R2Q1RK1 w kq - 0 1
Stockfish-1.6.3 (8 threads) is quite happy with Nxb6. I'll try a deeper search, but it may take a while.

Through depth 27, Stockfish is very happy with Nxb6. The move Nd6 was the second one Stockfish considered at depth 27, and it spent a long time before it concluded that Nxb6 was still better. Maybe a switch would occur at depth 28, but I think I'll give my cpus a rest now.

Code: Select all

Searching: rnbqk2r/pp1pbppp/1np5/8/2NP1p2/P6N/B2B2PP/R2Q1RK1 w kq -
infinite: 0 ponder: 0 time: 0 increment: 0 moves to go: 0
 2     -1.98   00:01      501 Rxf4 O-O 
 2     -1.78   00:01      571 Nxf4 O-O 
 2     -1.17   00:01      781 Nxb6 axb6 Rxf4 
 3     -1.98   00:01     2260 Nxb6 axb6 Qg4 g5 
 3     -1.54   00:01     2448 Nxf4 O-O Nh5 
 3     -1.29   00:01     2604 Rxf4 O-O Ne5 
 4     -1.54   00:01     4124 Rxf4 O-O Nxb6 axb6 Qh5 
 5     -1.62   00:01     6748 Rxf4 O-O Ne5 d5 Qh5 
 5     -1.17   00:01     8130 Qg4 g5 Ne5 d5 Qh5 
 6     -1.82   00:01    16636 Qg4 O-O Nxb6 axb6 Qxf4 d5 Bb1 
 7  <  -3.47   00:01    29890 Qg4 O-O Ne5 d5 Qxf4 f6 
 7     -1.54   00:01    33336 Ne5 O-O Rxf4 d5 Qh5 f5 Rf3 
 8     -1.54   00:01    43790 Ne5 O-O Qh5 d5 Nxf4 g6 Qh6 Nc4 Bxc4 dxc4 
 9  <  -1.82   00:01    75218 Ne5 O-O Qh5 d5 Nxf4 g6 Qh6 Bg5 
10     -1.86   00:01   244467 Ne5 O-O Qh5 d5 Bb1 g6 Qh6 Bxh3 Qxh3 Qc8 Qh6 
11     -2.26   00:01   584443 Ne5 O-O Rxf4 d5 Qh5 g6 Qh6 Bxh3 Qxh3 Bg5 Rf2 Bxd2 
                              Rxd2 
12     -2.46   00:01    1496k Ne5 O-O Rxf4 d5 Qh5 f5 Re1 Na6 Rf3 Qe8 Qxe8 Rxe8 
                              Ng5 h6 
13     -2.46   00:02    3589k Ne5 O-O Rxf4 d5 Qh5 f5 Bb1 Qe8 Qxe8 Rxe8 Bxf5 
                              Bxf5 Rxf5 N8d7 Nxd7 Nxd7 Rb1 g6 
14  <  -2.67   00:03    9464k Ne5 O-O Nxf4 d5 Qc2 N8d7 Nxd7 Nxd7 Bb1 g6 Nh5 Nf6 
15     -2.75   00:05   28690k Ne5 d5 Nxf4 O-O Qc2 N8d7 Nfd3 Bd6 Bb4 Bxb4 axb4 
                              Qg5 Bb1 Qe3+ Kh1 Nf6 Nc5 Qxd4 
15  >  -1.86   00:06   35670k Nxb6 Qxb6 Bxf7+ Kxf7 Qh5+ g6 Rxf4+ Kg8 Qe5 
16     +0.00   00:10   63450k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Kg8 Qh5 h6 Nd5 cxd5 
                              Qf7+ Kh7 Qf5+ Kg8 Qf7+ 
17     +0.00   00:15   99908k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rg8 Qb1 Rh8 Qd1 
18     +0.20   00:19  130807k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 Qf5 
                              d6 Qxh7 Nd7 Bg5 Nf8 Bxf6 Nxh7 Bxd8+ Kg6 Nf4+ Kf7 
                              Rae1 Bf5 Re7+ Kf6 Nh5+ Kg6 Bxb6 Nf6 Nf4+ Kg5 Rxb7 
                              Rxa3 
19     +0.00   00:25  179286k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 
                              Nxf6 gxf6 Qh5+ Rg6 Qxh7+ Rg7 Qh5+ Rg6 Rae1 d5 
                              Qh7+ Rg7 Qh5+ Rg6 Qh7+ 
20  >  +0.61   00:33  249713k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Rf8 Qg4 Rg8 Qf5 
                              d6 Qxh7 Nd7 Rxf6+ Nxf6 Rf1 Be6 Bg5 Kf8 Bxf6 gxf6 
                              Nxf6 Rg7 Nd7+ 
21     +0.61   00:56  441979k Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Bxa5 bxa5 
                              Qb3+ Kg6 Nxf6 gxf6 Qg3+ Kf7 Qxb8 d6 Rf3 Rg8 Rf2 
                              Re8 Raf1 f5 g4 Qf6 Qc7+ Kg8 gxf5 Qxd4 f6 Qg4+ Rg2 
22     +1.29   02:07    1003M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ Rd5 
                              Bh6 Rg8 Bxg7 Rxg7 Nxf6 Qxf6 Rxf6+ Kxf6 Rf1+ Rf5 
                              Rxf5+ Kxf5 Qf3+ Kg6 Qg3+ Kf7 Qxb8 Rg8 Qf4+ Kg6 
                              Qg4+ Kf7 Qf3+ Kg6 Qg3+ Kf7 Qb3+ d5 Qxb6 Ke6 Qc7 
                              h6 Qe5+ Kd7 Qf5+ Kd6 Qf4+ 
23     +1.66   05:36    2635M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ d5 Qg3 
                              Rg8 Qxb8 Kg6 Nxf6 gxf6 Qf4 Kf7 Bxa5 bxa5 Qh6 Rg7 
                              Rae1 Bd7 Re2 f5 Qh5+ Kf8 Rfe1 b5 Re3 b4 axb4 axb4 
                              Qh6 
24     +1.54   10:02    4737M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ d5 Qg3 
                              Rg8 Qxb8 Kg6 Nxf6 gxf6 Qf4 Kf7 Bxa5 bxa5 Qh6 Rg7 
                              Qh4 Qd6 Rae1 Bd7 Rf3 b5 Ree3 b4 Qh6 Bg4 Rf1 bxa3 
                              Rfe1 Qf8 Re8 
25     +1.94   47:46   22063M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ d5 Qg3 
                              Rg8 Qxb8 Kg6 Nxf6 gxf6 Qf4 Kf7 Qh6 Ra4 Rae1 Bd7 
                              Qxh7+ Rg7 Qh5+ Kg8 Bh6 Bg4 Re8+ Kh7 Rxd8 Bxh5 
                              Bxg7 Kxg7 Rd7+ Kg6 Rxb7 Be2 Rb1 Rxd4 Kf2 Bc4 
                              R1xb6 Rd2+ Kf3 
26     +2.22 2:22:52   66657M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ d5 Qg3 
                              Rg8 Qxb8 Kg6 Nxf6 gxf6 Qf4 Kf7 Qh6 Ra4 Rae1 Bd7 
                              Qxh7+ Rg7 Qh5+ Rg6 Bb4 Rxb4 axb4 Kg7 Qe2 Kg8 Qe7 
                              Qxe7 Rxe7 Rg7 Rfe1 Bf5 Rxg7+ Kxg7 Re7+ Kg6 Rxb7 
                              b5 
27     +2.18 5:10:13  147428M Nxb6 axb6 Bxf7+ Kxf7 Nxf4 Bf6 Nh5 Ra5 Qb3+ d5 Qg3 
                              Rg8 Qxb8 Kg6 Nxf6 gxf6 Qf4 Kf7 Qh6 Ra4 Rae1 Bd7 
                              Qxh7+ Rg7 Qh5+ Rg6 Bb4 Rxb4 axb4 Kg7 Qe2 Kg8 Qe7 
                              Qxe7 Rxe7 Rg7 Rfe1 Rf7 Kf2 Kf8 R7e3 Rh7 h3 Bf5 
                              Re8+ Kf7 R8e7+ Kg6 Rxh7 Kxh7 
Nodes: 237953996499
Nodes/second: 7914897
Best move: Nxb6
Ponder move: axb6

yanquis1972 · Post by **yanquis1972** » Fri Feb 26, 2010 10:41 pm

yes, after over an hour of interactive analysis w/ IDeA i am pretty satisfied Nxb6 is a winning shot as well. Nd6 was finally found, but with only a draw score. i am not sure Bh6 will be found within my lifetime on these settings (which are intentionally somewhat shallow), though i may try to coax it out.

acase · Post by **acase** » Sat Feb 27, 2010 1:40 am

1.Nxb6 possibly wins, however 1.Nd6+!! is craploads better...its not even close. In only 5-6 moves the evaluation even on Stockfish (which by the way is one of my favorite engines) on the main line shows that blacks game is completely smashed. Stockfish also doesn't find any improvements for black in the mainline either if you play it out manually (that is play each of white's moves in the manline and let Stockfish try to find something better for black after you make each white move).

1.Nd6+!! Bxd6 is forced, otherwise (if 1...Kf8) a forced mate for white is the result.

2.Bxf7+ Kxf7
(other moves by black like 2...Kf8 then 3.Bxf4! or if 2...Ke7 then 3.Nxf4! result in an eval of 6.00+ or more for white using Stockfish for the eval)

3.Nxf4 (at this point Stockfish STILL seems oblivious to the fact that blacks game is in shambles after more than an hour and agrees with the move for black in the main line, although it finally shows a +2.46 score for white it, gets the correct line wrong...(starting with 4.Rxf4+? see below)
3...Bxf4

3...Bxf4 4.Rxf4+ Kg8 5.Qh5 g6 6.Qh6 d5 7.Raf1 Bf5 8.Rxf5 N8d7 9.Rf7 Qf8 10.Rxf8+ Rxf8 11.Rxf8+ Nxf8 12.Qf4 h5 13.Bb4 Nfd7 14.Qc7 Kf7 15.Qxb7 Ra8 16.Kf2 g5 17.Bc5 Ke6 18.Qxc6+ Kf5 19.Qb7 Ke4 20.Ke2 g4 21.h3 gxh3 22.gxh3 h4 23.Qc7 Nxc5 24.dxc5
+- (2.46) Depth: 26 01:01:55 18873mN

4.Bxf4 Kg8
Stockfish agrees with this move and FINALLY sees the correct continuation, however 4....Qf6 might prolong the game a little more.

5.Bh6!!
after this move Stockfish's evaluation shoots through the roof (more than 8.00 for white), and yes, the inferior 5.Qh5 (though definately winning) would also work here.

5...d6 (all of the programs I tried play this move here)

6.Qh5 and here every program I tried shows 10.00 or higher for white including Stockfish. The threat is 7.Qf7 checkmate.

here is the final position with analysis by Stockfish 1.6.3 JA

[d]rnbq2kr/pp4pp/1npp3B/7Q/3P4/P7/6PP/R4RK1 b - - 0 1

Analysis by Stockfish 1.6.3 JA 64bit:

6...Be6 7.Rae1 Qe7 8.Bg5 Qd7 9.Qf3 h6
-+ (-6.46) Depth: 6 00:00:00 2kN
6...Be6 7.Rae1 Qe7 8.Rf3 N8d7 9.Rg3 Nf8 10.Rxg7+ Qxg7 11.Bxg7 Kxg7
-+ (-6.62) Depth: 7 00:00:00 20kN
6...Be6 7.Rae1 Qe7 8.Rf3 N8d7 9.Rg3 Nf8 10.Rxg7+ Qxg7 11.Bxg7 Kxg7 12.Qg5+
-+ (-5.89 --) Depth: 8 00:00:00 31kN
6...Be6 7.Rae1 Qe7 8.Rf3 N8d7 9.Rg3 Nf6 10.Qh3 Bxh3 11.Rxe7 Nh5 12.Rxh3 gxh6 13.Rxh5
-+ (-5.09) Depth: 9 00:00:00 61kN
6...Be6 7.Rae1 Qe7 8.Rf3 N8d7 9.Rg3 Nf6 10.Qh3 Bxh3 11.Rxe7 Nh5 12.Rxh3 gxh6 13.Rxh5 Rb8 14.Rxh6 Nd5 15.Rd7
-+ (-4.80) Depth: 10 00:00:00 89kN
6...Qe7 7.Rae1 Be6 8.Rf3 Na6 9.Rg3 Nc7 10.Bxg7 Qxg7 11.Rxg7+ Kxg7 12.Qg5+ Kf7
-+ (-5.69) Depth: 10 00:00:00 125kN
6...Qe7 7.Bg5 Qd7 8.Rae1 h6 9.Re7
-+ (-4.40 --) Depth: 11 00:00:00 285kN
6...Qe7 7.Bg5 Qd7 8.Rae1 h6 9.Re7 Qxe7 10.Bxe7 Nd5 11.Bxd6 Kh7 12.Be5 Na6
-/+ (-1.33) Depth: 12 00:00:00 576kN
6...Be6 7.Rae1 Qe7 8.Rf3 N8d7 9.Rg3 Nf6 10.Qh3 Bxh3 11.Rxe7 Nh5 12.Rxh3 gxh6 13.Rxh5 Nd5 14.Rxb7
-+ (-4.44) Depth: 12 00:00:00 602kN
6...Be6 7.Rae1 Qe7 8.Rxe6 Qxe6 9.Qg5 Qd7 10.Bxg7 Qe8 11.Bh6+ Qg6 12.Rf8#
+/- (0.80 --) Depth: 13 00:00:00 1231kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Kf7 10.Bxg7 Kxe6 11.Bxf6 Qe8 12.Qf5+ Kf7 13.Qg4 Qe3+ 14.Kh1 Ke8 15.Bxh8 Qe7 16.Bf6 Qf7 17.Re1+ Kf8
+/- (0.92) Depth: 14 00:00:00 2327kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Kf7 10.Bxg7 Kxe6 11.Bxf6 Qe8 12.Qf5+ Kf7 13.Qg4 Qe3+ 14.Kh1 Ke8 15.Bxh8 Kd8 16.Rf8+ Kc7 17.Rf7+ Kb8 18.h3 a6 19.Qg7 Ra7 20.Qg8+ Nc8 21.Qxh7 Qxa3
+/- (0.72) Depth: 15 00:00:00 3546kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Kf7 10.Bxg7 Kxe6 11.Bxf6 Kd7 12.Bxd8 Raxd8 13.Rf7+ Kc8 14.Qg7 Nd5 15.Rxb7 Rhe8 16.Rxa7 Re1+ 17.Kf2 Rb1 18.Ra8+ Rb8 19.Ra6 Rb2+ 20.Kg3 Nb6 21.Ra7 Nd5 22.Qxh7 Rb3+ 23.Kh4 Rb2 24.a4
+- (4.16) Depth: 16 00:00:01 8494kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Qd7 10.Rexf6 Qe7 11.Rf8+ Rxf8 12.Qxe7 Rxf1+ 13.Kxf1 gxh6 14.Qxb7 Nd5 15.Qxc6 Nf6 16.Qxd6 Kg7 17.Qc7+ Kg6 18.Qxa7 Rc8 19.Qa4 Re8 20.Qc2+ Re4 21.Kf2 Kf5 22.Qc5+ Ke6
+- (4.20) Depth: 17 00:00:03 17598kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Qc7 10.Rexf6 Qe7 11.Rf8+ Rxf8 12.Qxe7 Rxf1+ 13.Kxf1 gxh6 14.Qxb7 Nd5 15.Qxc6 Nf6 16.Qxd6 Kf7 17.Qc7+ Ke6 18.Qxa7 Rd8 19.Ke2 h5 20.a4 Nd5 21.Qxh7 Nf4+ 22.Ke3 Nxg2+ 23.Ke4
+- (4.44) Depth: 18 00:00:05 29267kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Qc7 10.Rexf6 Qe7 11.Rf8+ Rxf8 12.Qxe7 Rxf1+ 13.Kxf1 gxh6 14.Qxb7 Nd5 15.Qxa7 Nf6 16.Qc7 Kf8 17.Qxd6+ Kf7 18.Qc7+ Kg6 19.a4 Re8 20.Qxc6 Re4 21.d5 Kf5 22.d6 Rf4+ 23.Ke2 Ke6
+- (4.92) Depth: 19 00:00:07 42333kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Qc7 10.Rexf6 Qe7 11.Rf8+ Rxf8 12.Qxe7 Rxf1+ 13.Kxf1 gxh6 14.Qxb7 Nd5 15.Qxa7 Nf6 16.Qc7 Kf8 17.Qxd6+ Kf7 18.Qc7+ Kg6 19.a4 Re8 20.Qxc6 Re4 21.Qd6 Kf5 22.Qc5+ Ke6 23.a5 Ng4 24.Qc6+ Kf5 25.Qd7+ Kf6 26.a6 Nxh2+ 27.Kf2
+- (5.13) Depth: 20 00:00:10 62490kN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Kf7 10.Bxg7 Kxe6 11.Qf5+ Kf7 12.Bxf6 Qe8 13.Qg4 Qe3+ 14.Kh1 Raf8 15.Bg5+ Ke8 16.Rxf8+ Rxf8 17.Bxe3 Rf1+ 18.Bg1 Rf7 19.Qe6+ Re7 20.Qxd6 a6 21.Qb8+ Kf7 22.Bf2 Nc4 23.Qf4+ Kg6 24.Qg4+ Kf7 25.Qf5+ Kg7
+- (5.21) Depth: 21 00:00:17 104mN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Qc7 10.Rexf6 Qe7 11.Rf8+ Rxf8 12.Qxe7 Rxf1+ 13.Kxf1 gxh6 14.Qxb7 Nd5 15.Qxa7 Kf8 16.Qd7 Rg8 17.Qxd6+ Ne7 18.Qxh6+ Kf7 19.Qxh7+ Ke6 20.Qh3+ Kd6 21.g4 Nd5 22.Qg3+ Kd7 23.g5 Rf8+ 24.Ke2 Re8+ 25.Kd2 Re4 26.Qd3 Rf4 27.Ke2 Rf7 28.Qc4
+- (5.53) Depth: 22 00:00:25 156mN
6...Be6 7.Rae1 Qd7 8.Bxg7 Qf7 9.Rxf7 Bxf7 10.Qh6 N8d7 11.Re7 Rf8 12.Bxf8 Nxf8 13.Qf6
+- (6.26 --) Depth: 23 00:00:44 274mN
6...Be6 7.Rae1
+- (9.49 --) Depth: 24 00:01:24 513mN
6...Be6 7.Rae1 N8d7 8.Rxe6 Nf6 9.Qg5 Qc7 10.Rexf6 Nd5 11.Rxd6 Rf8 12.Rxf8+ Kxf8 13.Rd8+ Qxd8 14.Qxd8+ Kf7 15.Qxh8 gxh6 16.Qxh7+ Ke6 17.Qxb7 Kd6 18.Qxa7 h5 19.Qg7 Ke6 20.Qe5+ Kd7 21.Qxh5 Nc7 22.h4 Ne6 23.d5 Nc5 24.g4 Kd6 25.dxc6 Kxc6 26.Kf2 Kd6 27.Qf5
+- (13.77) Depth: 25 00:04:48 1707mN

Test Position: 1.Nd6+!!

Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!

Re: Test Position: 1.Nd6+!!