Is the exchange sac good here?

[AdminX]

Black to move

Nidjat Mamedov vs Valentin Lotov

[d]1k4rr/pb3q2/1pn1pb2/3p2pN/3P2Pn/P3BN2/1P2QP2/3RR1KB b - - 0 0

Is the exchange sac Rxh5 good here?

[M ANSARI]

More likely loading up the position is better since white can seem to trade Queens and thus things are not as dangerous. Probably Rh7 or Rh6 is better ... engines can't decide what they want here ... at least on my little laptop. Many like the sac but don't seem to have a good follow up. Probably on bigger hardware the position would clear up very quickly.

[AdminX]

The position is after white's 24th move. The sac was not played, but I wondered if it was good. From a human perspective it looks like black could get some good play against whites weak kingside. If not Rxh5 then maybe e5 could be a good try for a win here. Either way I think black was better here. Here is the complete game. The game as a whole was not much to look at, I felt as if the players really did not have much fight in them.

[Event "Young Masters "]
[Site "Event Location"]
[Date "2008.08.03"]
[Round "?"]
[White "Mamedov, Nidjat"]
[Black "Lotov, Valentin"]
[Result "1/2-1/2"]
[PlyCount "49"]
[EventDate "2008.??.??"]

1. Nf3 Nf6 2. g3 d5 3. Bg2 e6 4. O-O Be7 5. d3 b6 6. Nbd2 Bb7 7. e4 c5 8. e5
Nfd7 9. Re1 Nc6 10. Qe2 Qc7 11. c3 g5 12. h3 h5 13. g4 hxg4 14. hxg4 Nf8 15.
Nf1 Ng6 16. d4 Nh4 17. Be3 O-O-O 18. Ng3 Rdg8 19. Rad1 Kb8 20. a3 cxd4 21. cxd4
f6 22. exf6 Bxf6 23. Bh1 Qf7 24. Nh5 Bd8 25. Bc1 1/2-1/2

[royb]

An interesting question Ted. I thought it looked good to my patzer eyes but Rybka 2.3.2a 64-bit with 1024 MB of hash and about 20 mins to ponder thinks otherwise:

5 -0.33 Be7 Nxh4 (0.04)
6 -0.28 Be7 Rc1 Nxf3+ Qxf3 Qg6 (0.23)
7 -0.35 Be7 Rc1 Nxf3+ Qxf3 Qg6 Qg3+ Ka8 (0.47)
8 -0.34 Be7 Rc1 Nxf3+ Qxf3 Qg6 Qg3+ Ka8 Bf3 (0.71)
9 -0.33 Be7 Rc1 Nxf3+ Qxf3 Qg6 Qg3+ Ka8 Rc3 Rd8 (1.14)
10 -0.34 Be7 Rc1 Nxf3+ Qxf3 Qg6 Qg3+ Ka8 Rc3 Rd8 f4 (1.91)
11 -0.25 Be7 b4 Nxf3+ Qxf3 Qg6 Qe2 Bd6 Bg2 Rc8 Rc1 (4.63)
12 -0.27 Be7 b4 Nxf3+ Qxf3 Qg6 Qe2 Rh6 Bg2 Bd6 f4 gxf4 (8.12)
13 -0.20 Be7 b4 Nxf3+ Qxf3 Qg6 Qe2 Rh6 Bg2 Bd6 f4 gxf4 Bxf4 Bxf4 Nxf4 (13.90)
14 -0.16 Be7 b4 Nxf3+ Qxf3 Qg6 Qe2 Rh6 Bg2 Bd6 Rc1 Qf7 Qd2 Qe7 (37.45)
15 -0.12 Be7 b4 Rh7 b5 Nxf3+ Qxf3 Qxf3 Bxf3 Na5 Rd3 Nc4 Bc1 Bc8 Bg2 (103.64)
15 -0.15 Bd8 b4 Nxf3+ Qxf3 Qg6 Qe2 Rh6 b5 Na5 Qd3 Qxd3 Rxd3 Nc4 Bg2 (121.81)
15 -0.36 e5 Nxf6 Qxf6 dxe5 Nxf3+ Bxf3 Qxe5 Bd4 Qh2+ Kf1 Nxd4 Rxd4 Rf8 Bg2 (181.66)
16 -0.28 e5 Nxf6 Qxf6 dxe5 Nxf3+ Bxf3 Qxe5 Bd4 Qh2+ Kf1 Nxd4 Rxd4 Rf8 Bg2 (224.45)
17 -0.26 e5 Nxh4 Rxh5 Nf5 Rhh8 dxe5 Nxe5 Bg2 Qh7 Bd4 Re8 Qb5 Qh2+ Kf1 (398.96)
18 -0.29 e5 dxe5 Nxe5 Nxe5 Bxe5 Bd4 Bxd4 Rxd4 Re8 Qd2 Rxe1+ Qxe1 Re8 Qd2 (761.21)
19 -0.23 e5 dxe5 Nxe5 Nxe5 Bxe5 Bd4 Bxd4 Rxd4 Re8 Qd2 Rxe1+ Qxe1 Re8 Qd2 (1238.79)

It is interesting to see that for a bit (at ply 17) it was contemplating making the exchange sacrifice after first playing e5 (with Nxh4 by White after e5) but it later thinks that a massive trade-off of pieces is the best Black can do here with a small advantage.

I wish I had Aquarium to work on this type of position - I think that is one of the big benefits of the IDeA concept -- having it pay particular attention to one or two specific moves... [At least as I understand it without having obtained the software yet!]

Roy

[Eelco de Groot]

I was surprised that Ancalagon in its present buggy state never once considers playing Rybka's move, 24... e5, not in top three anywhere, I would be interested to see what Rybka III plays here and what difference it makes if Human or Dynamic Rybka is analyzing. Ancalagon did have Rxh5 at the top of the move list for a while but then the eval came down gradually. But it is possible that the programs just don't see deep enough into a King attack. Falling score is usually a sign that the move leads to difficulties though, 24... Bd8 seems like a prudent move if you don't really need to win in a tournament. I was happy to see that move eventually and Rybka 2.3.2a does not play it but the human GM Valentin Lotov played it so that is why I highlighted that move !

Eelco

1k4rr/pb3q2/1pn1pb2/3p2pN/3P2Pn/P3BN2/1P2QP2/3RR1KB b - -

Engine: Ancalagon 1.08 Testversion 002 (256 MB)
by Tord Romstad

15 5:05 +1.03 24...Ka8 25.Bc1 Qf8 26.b4 Nxf3+
27.Qxf3 Bxd4 28.Rxe6 Qc8 29.Rxc6 Qxc6
30.Qxd5 Qxd5 31.Bxd5 Bxd5 32.Rxd4 Bf3
33.Bxg5 Rxg5 (99.927.871) 326

15 5:05 +0.86 24...Bd8 25.Bc1 Nxf3+ 26.Qxf3 Qg6
27.Qe2 Rh6 28.Bg2 Bc7 29.b4 Rf8
30.Kh1 Ne7 31.Bf3 Ba6 32.b5 (99.927.871) 326

15 5:05 +0.84 24...Rxh5 25.gxh5 Qxh5 26.Nxh4 Qxh4
27.Qf3 Bd8 28.Bg2 Bc7 29.Qh3 Qxh3
30.Bxh3 g4 31.Bg2 g3 32.fxg3 Bxg3
33.Rc1 (99.927.871) 326

__________________________________________________________________


16 11:18 +1.17 24...Bd8 25.Bc1 Nxf3+ 26.Qxf3 Qg6
27.Qe2 Rh6 28.Bg2 Bc7 29.Qf3 Ba6
30.Bf1 Bxf1 31.Kxf1 Bd6 32.Qc3 Rc8
33.Kg1 (218.866.159) 322

16 11:18 +0.76 24...Ka8 25.Bc1 Qf8 26.b4 Be7 27.Bg2 Nxg2
28.Kxg2 Rh6 29.Kg1 b5 30.Be3 Kb8
31.Kf1 Qf7 32.Ng3 Rf8 (218.866.159) 322

16 11:18 +0.66 24...Rxh5 25.gxh5 Qxh5 26.Nxh4 Qxh4
27.Qf3 Bd8 28.Bg2 Bc7 29.Qh3 Qxh3
30.Bxh3 g4 31.Bg2 g3 32.Rd2 gxf2+
33.Rxf2 Ba6 34.Rf7 (218.866.159) 322

__________________________________________________________________


16 17:09 +1.17 24...Bd8 25.Bc1 Nxf3+ 26.Qxf3 Qg6
27.Qe2 Rh6 28.Bg2 Bc7 29.Qf3 Ba6
30.Bf1 Bxf1 31.Kxf1 Bd6 32.Qc3 Rc8
33.Kg1 (332.720.006) 323

16 17:09 +0.76 24...Ka8 25.Bc1 Qf8 26.b4 Be7 27.Bg2 Nxg2
28.Kxg2 Rh6 29.Kg1 b5 30.Be3 Kb8
31.Kf1 Qf7 32.Ng3 Rf8 (332.720.006) 323

16 17:09 +0.76 24...Qf8 25.b4 Be7 26.Bc1 Ka8 27.Bg2 Nxg2
28.Kxg2 Rh6 29.Kg1 b5 30.Be3 Kb8
31.Kf1 Qf7 32.Ng3 Rf8 (332.720.006) 323

__________________________________________________________________


17 33:09 +0.90 24...Bd8 25.Bc1 Nxf3+ 26.Qxf3 Qg6
27.Bg2 Bc7 28.Qf6 Bc8 29.Qxg6 Rxg6
30.f3 Rf8 31.Kh1 e5 32.dxe5 Nxe5
33.Re3 Rc6 34.Kg1 (646.228.166) 324

17 33:09 +0.80 24...Qf8 25.b4 Be7 26.Bc1 Ka8 27.Bg2 Nxg2
28.Kxg2 Rh6 29.Kg1 a6 30.Be3 Rhh8
31.Kf1 Kb8 32.Rd2 Qf7 33.Kg1 (646.228.166) 324

17 33:09 +0.47 24...Ka8 25.Nxh4 Rxh5 26.gxh5 gxh4+
27.Kh2 Qc7+ 28.f4 Nxd4 29.Rxd4 Bxd4
30.Bf3 Bf6 31.Rg1 Rf8 32.Qg2 h3
33.Qe2 Qe7 34.Rg5 Rh8 35.Kxh3 (646.228.166) 324

__________________________________________________________________


17 44:23 +0.90 24...Bd8 25.Bc1 Nxf3+ 26.Qxf3 Qg6
27.Bg2 Bc7 28.Qf6 Bc8 29.Qxg6 Rxg6
30.f3 Rf8 31.Kh1 e5 32.dxe5 Nxe5
33.Re3 Rc6 34.Kg1 (863.319.545) 324

17 44:23 +0.80 24...Qf8 25.b4 Be7 26.Bc1 Ka8 27.Bg2 Nxg2
28.Kxg2 Rh6 29.Kg1 a6 30.Be3 Rhh8
31.Kf1 Kb8 32.Rd2 Qf7 33.Kg1 (863.319.545) 324

17 44:23 +0.70 24...Be7 25.Bc1 Qf8 26.b4 Ka8 27.Bg2 Nxg2
28.Kxg2 Rh6 29.Kg1 a6 30.Be3 Ka7
31.Kf1 Kb8 32.Rc1 Rgh8 33.Kg1 (863.319.545) 324

[Ovyron]

I wish I had Aquarium to work on this type of position

After 200 positions for main line and Rxh5, IDeA thinks that Rxh5 draws while black can keep the advantage with other moves:

[AdminX]

I was happy to see that move eventually and Rybka 2.3.2a does not play it but the human GM Valentin Lotov played it so that is why I highlighted that move !

Eelco

In the game posted above GM Valentin Lotov did NOT play Rxh5, However I wonder what would have happened if he did.

[M ANSARI]

Here is R3 response after 5 min on Quad. It seems all of the 3 versions prefer Bd8 and only going for the exchange sac if b4 is played ... disregard the time in Human as I accidentally turned the mouse wheel ... but the depth is ok.

New game
1k4rr/pb3q2/1pn1pb2/3p2pN/3P2Pn/P3BN2/1P2QP2/3RR1KB b - - 0 1

Analysis by Rybka 3 :

1...Be7
=/+ (-0.36) Depth: 3 00:00:00
1...Be7
=/+ (-0.36) Depth: 3 00:00:00
1...Be7
=/+ (-0.36) Depth: 3 00:00:00
1...Bd8 2.b4 Nxf3+
=/+ (-0.39) Depth: 4 00:00:00
1...Bd8 2.b4 Nxf3+
=/+ (-0.39) Depth: 4 00:00:00
1...Bd8 2.b4 Nxf3+
=/+ (-0.39) Depth: 6 00:00:00
1...Bd8 2.b4 Nxf3+
=/+ (-0.39) Depth: 6 00:00:00 8kN
1...Be7 2.b4 Nxf3+ 3.Qxf3 Qxf3 4.Bxf3 Rc8
= (-0.22) Depth: 7 00:00:00 23kN
1...Be7 2.b4 Nxf3+ 3.Qxf3 Qxf3 4.Bxf3 Rc8 5.Be2
= (-0.13) Depth: 8 00:00:00 39kN
1...Bd8 2.b4 Nxf3+ 3.Qxf3 Qc7 4.b5 Na5 5.Bd2 Rf8 6.Qg3 Qxg3+
= (-0.17) Depth: 8 00:00:00 53kN
1...Bd8 2.b4 Nxf3+ 3.Qxf3 Qc7 4.b5 Na5 5.Bd2 Rf8 6.Qg3 Qxg3+
= (-0.17) Depth: 9 00:00:00 83kN
1...Rh6 2.b4 Nxf3+ 3.Qxf3 Ba6 4.Nxf6 Rxf6 5.Qg3+ Kb7
=/+ (-0.36) Depth: 9 00:00:00 110kN
1...Rh6 2.Rc1 Nxf3+ 3.Qxf3 Qc7 4.Qd1 Qd6 5.b4 e5 6.dxe5
=/+ (-0.29) Depth: 10 00:00:01 232kN
1...Rh6 2.Rc1 Nxf3+ 3.Qxf3 Qc7 4.Qe2 Qd6 5.Red1 Rf8 6.Bg2
=/+ (-0.32) Depth: 11 00:00:02 396kN
1...Rh6 2.Rc1 Ka8 3.b4 Bh8 4.Nxg5 Nxd4 5.Nxf7 Nxe2+ 6.Rxe2 Rxh5 7.g5 d4 8.Bxb7+
= (-0.18) Depth: 12 00:00:04 874kN
1...Rh6 2.Rc1 Qe7 3.Red1 Nxf3+ 4.Qxf3 Bh8 5.b4 Rh7 6.Qe2 Rf7
= (-0.14) Depth: 13 00:00:13 2415kN
1...Bd8 2.b4 a6 3.Rc1 Bc7 4.Rc2 Nxf3+ 5.Qxf3 Qe7 6.Qe2 Qd6 7.f3
= (-0.15) Depth: 13 00:00:20 3985kN
1...Be7 2.b4 Rh7
= (-0.22) Depth: 13 00:00:20 4046kN
1...Be7 2.b4 Rh7 3.Bc1 Bc8 4.Be3 Nxf3+ 5.Bxf3 Ba6
= (-0.20) Depth: 14 00:00:24 4724kN
1...Be7 2.b4 Rh7 3.Bc1 Bc8 4.Be3 Nxf3+ 5.Bxf3 Ba6
= (-0.23) Depth: 15 00:00:31 5919kN
1...Bd8
=/+ (-0.40) Depth: 15 00:00:54 11327kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qd3 Rh6 5.b4 Bc7 6.Bb2 Qd6 7.Qg3 Qe7 8.Qd3 Rc8 9.Rc1
=/+ (-0.45) Depth: 15 00:01:16 16272kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qd3 Rh6 5.b4 Bc7 6.Bb2 Qd6 7.Qg3 Qe7 8.Qd3 Rc8 9.Rc1
=/+ (-0.45) Depth: 16 00:01:31 19305kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qe2 Re8 5.f4 gxf4 6.Bxf4+ Ka8 7.Bg2 b5 8.b4 Reg8 9.Be3 Qe7 10.Rf1 Bc7
=/+ (-0.48) Depth: 17 00:02:25 30576kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qe2 Re8 5.f4 gxf4 6.Bxf4+ Ka8 7.Bg2 b5 8.Rf1 Reg8 9.Rf2 Qe7 10.Kf1 a6 11.Bf3 Rf8
=/+ (-0.46) Depth: 18 00:03:07 39379kN

(, 04.08.2008)





New game
1k4rr/pb3q2/1pn1pb2/3p2pN/3P2Pn/P3BN2/1P2QP2/3RR1KB b - - 0 1

Analysis by Rybka 3 Dynamic :

1...Rxh5
=/+ (-0.32) Depth: 2 00:00:00
1...Be7
=/+ (-0.32) Depth: 3 00:00:00
1...Be7
=/+ (-0.36) Depth: 3 00:00:00
1...Be7
=/+ (-0.36) Depth: 4 00:00:00
1...Be7 2.b4
= (-0.25) Depth: 5 00:00:00
1...Be7 2.b4 Nxf3+
=/+ (-0.37) Depth: 6 00:00:00 7kN
1...Be7 2.b4 a6 3.Bc1
= (-0.20) Depth: 7 00:00:00 14kN
1...Rxh5 2.gxh5 Qxh5 3.Ne5 Qxe2
=/+ (-0.53) Depth: 7 00:00:00 27kN
1...Rxh5 2.gxh5 Qxh5 3.Ne5 Qxe2
=/+ (-0.53) Depth: 8 00:00:00 32kN
1...Rxh5 2.gxh5 Qxh5 3.Ne5 Qxe2 4.Nxc6+ Bxc6 5.Rxe2 Nf5 6.b3 Kb7
=/+ (-0.43) Depth: 9 00:00:00 49kN
1...Rxh5 2.gxh5 Qxh5 3.Nxh4 Qxh4 4.Qf3
=/+ (-0.39) Depth: 10 00:00:01 133kN
1...Rxh5 2.gxh5 Qxh5 3.Nxh4 Qxh4 4.Qf3 Bd8 5.Bg2 Bc7
=/+ (-0.28) Depth: 11 00:00:01 251kN
1...Rxh5 2.gxh5 Qxh5 3.Nxh4 Qxh4 4.Qf3 Qh6 5.Qg3+ Ka8
= (-0.18) Depth: 12 00:00:06 1065kN
1...Be7 2.b4 Rxh5 3.gxh5 Qxh5 4.Ne5 Qxe2 5.Nxc6+ Bxc6 6.Rxe2 Nf5 7.Rc1 Bb5
=/+ (-0.32) Depth: 12 00:00:09 1621kN
1...Bd8
=/+ (-0.48) Depth: 12 00:00:10 1775kN
1...Bd8 2.b4 Nxf3+
=/+ (-0.44) Depth: 12 00:00:10 1922kN
1...Bd8 2.b4 Nxf3+
=/+ (-0.44) Depth: 13 00:00:13 2317kN
1...Bd8 2.b4 Rxh5 3.gxh5 Qf5 4.Bc1 Qg4+
=/+ (-0.42) Depth: 14 00:00:17 3200kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qe7 4.Qd3
=/+ (-0.37) Depth: 15 00:00:34 6749kN
1...Be7 2.b4 Rxh5 3.gxh5 Bd6 4.b5 Qxh5 5.Nxh4 Qxh4 6.Bg2 Na5 7.Qf3 Nc4 8.Qh3 Qxh3 9.Bxh3 g4 10.Bf1 g3
=/+ (-0.40) Depth: 15 00:00:48 9786kN
1...Be7 2.Bc1 Nxf3+ 3.Qxf3
=/+ (-0.38) Depth: 16 00:01:28 17117kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qe2 Rh6 5.b4 Bc7 6.b5 Na5 7.a4
=/+ (-0.45) Depth: 16 00:01:53 22349kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qe2 Rh6 5.b4 Bc7 6.b5 Na5 7.a4 Nc4 8.Bg2 Qd6 9.Rd3 Qe7
=/+ (-0.45) Depth: 17 00:02:54 34782kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qe2 Rh6 5.b4 Bc7 6.b5 Na5 7.a4 Nc4 8.Bg2 Bd6 9.Rd3 Qe7 10.Rf3
=/+ (-0.55) Depth: 18 00:03:40 44206kN

(, 04.08.2008)


New game
1k4rr/pb3q2/1pn1pb2/3p2pN/3P2Pn/P3BN2/1P2QP2/3RR1KB b - - 0 1

Analysis by Rybka 3 Human :

1...e5 2.dxe5
=/+ (-0.40) Depth: 2 00:00:00
1...e5 2.dxe5
=/+ (-0.32) Depth: 3 00:00:00
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qe2 Rh6 5.b4 Bc7 6.b5 Na5 7.a4 Nc4 8.Bg2 Bd6 9.Qc2 Qe7 10.Qd3 Rc8 11.Re2 Rf8 12.Rde1
=/+ (-0.39) Depth: 18 00:00:00 0kN
1...Bd8 2.Bc1 Nxf3+ 3.Qxf3 Qd7 4.Qe2 Rh6 5.b4 Bc7 6.b5 Na5 7.a4 Nc4 8.Bg2 Bd6 9.Qc2 Qe7 10.Qd3 Rc8 11.Re2 Rf8 12.Rde1
=/+ (-0.39) Depth: 19 00:00:00 0kN

(, 04.08.2008)