A combination by Rybka

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jdart
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A combination by Rybka

Post by jdart »

This position was reached in a match Loop vs. Rybka 2.3.2a, part of the CEGT test series organized by Heinz van Kempen
(http://www.husvankempen.de/nunn/).

[d] 2r3k1/2rnpb2/3p1p2/3P2pP/pqN1P1P1/Np1B1Q1R/8/5R1K b - -

Here, Rybka played .. Rxc4 with a score of +1.54 and Loop failed low on the next move (-2.06).

This is pretty impressive - my program doesn't want to play this, but if I force the continuation Nxc4 Rxc4 Bxc4 Qxc4 and then search, it fails low for White at ply 13.

--Jon
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Uri Blass
Posts: 10965
Joined: Thu Mar 09, 2006 12:37 am
Location: Tel-Aviv Israel

Re: A combination by Rybka

Post by Uri Blass »

jdart wrote:This position was reached in a match Loop vs. Rybka 2.3.2a, part of the CEGT test series organized by Heinz van Kempen
(http://www.husvankempen.de/nunn/).

[d] 2r3k1/2rnpb2/3p1p2/3P2pP/pqN1P1P1/Np1B1Q1R/8/5R1K b - -

Here, Rybka played .. Rxc4 with a score of +1.54 and Loop failed low on the next move (-2.06).

This is pretty impressive - my program doesn't want to play this, but if I force the continuation Nxc4 Rxc4 Bxc4 Qxc4 and then search, it fails low for White at ply 13.

--Jon
I think that this is a positional decision
Movei likes that move relatively fast(depth 9) but needs time to see big advantage

Hardware A3000
Hash 512 mbytes

New game
2r3k1/2rnpb2/3p1p2/3P2pP/pqN1P1P1/Np1B1Q1R/8/5R1K b - - 0 1

Analysis by Movei00_8_438:

1...Rc7xc4
± (0.95) Depth: 1 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4
± (0.95) Depth: 2 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4
± (0.95) Depth: 2 00:00:00
1...Rc7xc4
± (1.25) Depth: 3 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4
± (0.95) Depth: 3 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4
± (0.95) Depth: 3 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4
± (0.95) Depth: 4 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4
± (0.95) Depth: 4 00:00:00
1...Rc7xc4
± (1.25) Depth: 5 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-f5
± (1.38) Depth: 5 00:00:00
1...Nd7-c5
± (1.37) Depth: 5 00:00:00
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-f5
± (1.38) Depth: 5 00:00:00
1...Nd7-e5
± (1.37) Depth: 5 00:00:00
1...Nd7-e5
± (1.08) Depth: 5 00:00:00
1...Nd7-e5 2.Nc4xe5 d6xe5 3.Na3-b5 Rc7-c1
± (0.75) Depth: 5 00:00:00
1...Nd7-e5 2.Nc4xe5 d6xe5 3.Na3-b5 Rc7-c1
± (0.75) Depth: 5 00:00:00
1...Nd7-e5
± (1.05) Depth: 6 00:00:00 7kN
1...Nd7-e5 2.Nc4xe5 d6xe5 3.Na3-b5 Rc7-c1 4.h5-h6 Kg8-h8
± (1.32) Depth: 6 00:00:00 9kN
1...Nd7-c5
± (1.31) Depth: 6 00:00:02 10kN
1...Nd7-e5 2.Nc4xe5 d6xe5 3.Na3-b5 Rc7-c1 4.h5-h6 Kg8-h8
± (1.32) Depth: 6 00:00:03 12kN
1...Rc7xc4
± (1.31) Depth: 6 00:00:03 13kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Nd7-e5 4.Qf3-f5 Qb4xc4
± (1.21) Depth: 6 00:00:03 15kN
1...e7-e6
± (1.20) Depth: 6 00:00:03 26kN
1...e7-e6 2.h5-h6 e6xd5 3.e4xd5 Rc7xc4 4.Na3xc4 Rc8xc4 5.h6-h7+ Kg8-h8 6.Bd3xc4 Qb4xc4
± (1.20) Depth: 6 00:00:03 33kN
1...e7-e6 2.h5-h6 e6xd5 3.e4xd5 Rc7xc4 4.Na3xc4 Rc8xc4 5.h6-h7+ Kg8-h8 6.Bd3xc4 Qb4xc4
± (1.20) Depth: 6 00:00:03 40kN
1...e7-e6
+- (1.50) Depth: 7 00:00:04 42kN
1...e7-e6 2.h5-h6 e6xd5 3.e4xd5 Rc7xc4 4.Na3xc4 Rc8xc4 5.h6-h7+ Kg8-h8 6.Bd3xc4 Qb4xc4
± (1.20) Depth: 7 00:00:04 54kN
1...e7-e6 2.h5-h6 e6xd5 3.e4xd5 Rc7xc4 4.Na3xc4 Rc8xc4 5.h6-h7+ Kg8-h8 6.Bd3xc4 Qb4xc4
± (1.20) Depth: 7 00:00:04 71kN
1...e7-e6
+- (1.50) Depth: 8 00:00:04 84kN
1...e7-e6 2.h5-h6 e6xd5 3.e4xd5 Rc7xc4 4.Na3xc4 Rc8xc4 5.Bd3xc4 Qb4xc4 6.h6-h7+ Kg8-h8
± (1.20) Depth: 8 00:00:04 123kN
1...Rc7xc4
± (1.19) Depth: 8 00:00:04 130kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-f5 a4-a3 5.h5-h6 a3-a2 6.Rf1-a1
± (1.19) Depth: 8 00:00:04 138kN
1...Nd7-e5
± (1.18) Depth: 8 00:00:04 149kN
1...Nd7-e5
± (0.89) Depth: 8 00:00:04 158kN
1...Nd7-e5 2.Nc4xe5 d6xe5 3.d5-d6 e7xd6 4.Na3-b5 Rc7-c1 5.Qf3xf6 Rc1xf1+ 6.Qf6xf1
² (0.66) Depth: 8 00:00:07 171kN
1...Nd7-e5 2.Nc4xe5 d6xe5 3.d5-d6 e7xd6 4.Na3-b5 Rc7-c1 5.Qf3xf6 Rc1xf1+ 6.Qf6xf1
² (0.66) Depth: 8 00:00:07 180kN
1...Nd7-e5
± (0.96) Depth: 9 00:00:07 191kN
1...Nd7-e5 2.Nc4xe5 d6xe5 3.d5-d6 Rc7-d7 4.Qf3-f5 Qb4xd6 5.h5-h6 Qd6-d4 6.h6-h7+ Kg8-h8
± (1.19) Depth: 9 00:00:07 214kN
1...Rc7xc4
± (1.18) Depth: 9 00:00:09 229kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-f5 a4-a3 5.h5-h6 a3-a2 6.h6-h7+ Kg8-h8 7.Rf1-a1
± (1.13) Depth: 9 00:00:09 248kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-f5 a4-a3 5.h5-h6 a3-a2 6.h6-h7+ Kg8-h8 7.Rf1-a1
± (1.13) Depth: 9 00:00:11 354kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-f5
± (0.85) Depth: 10 00:00:11 408kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-f5
± (0.85) Depth: 10 00:00:13 521kN
1...Rc7xc4
² (0.55) Depth: 11 00:00:13 649kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-f5 e7-e6 5.d5xe6 Bf7xe6 6.Qf5-g6+ Kg8-f8 7.Rf1-g1 Qc4-e2 8.Rh3-g3
² (0.40) Depth: 11 00:00:13 774kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-f5 e7-e6 5.d5xe6 Bf7xe6 6.Qf5-g6+ Kg8-f8 7.Rf1-g1 Qc4-e2 8.Rh3-g3
² (0.40) Depth: 11 00:00:15 1016kN
1...Rc7xc4
= (0.10) Depth: 12 00:00:15 1392kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-d1 e7-e6 6.d5xe6 Bf7xe6 7.Qd1xd6 Be6xg4 8.Qd6-d8+ Kg8-h7 9.Qd8-e7+ Kh7-g8
= (0.20) Depth: 12 00:00:15 1632kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-d1 e7-e6 6.d5xe6 Bf7xe6 7.Qd1xd6 Be6xg4 8.Qd6-d8+ Kg8-h7 9.Qd8-e7+ Kh7-g8
= (0.20) Depth: 12 00:00:16 2512kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-d1 e7-e6 6.d5xe6 Qc4xe6 7.Rh3-g3 a4-a3 8.Re1-f1 a3-a2
= (0.13) Depth: 13 00:00:17 3222kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-d1 e7-e6 6.d5xe6 Qc4xe6 7.Rh3-g3 a4-a3 8.Re1-f1 a3-a2
= (0.13) Depth: 13 00:00:20 4387kN
1...Rc7xc4
= (-0.17) Depth: 14 00:00:27 7432kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-d1 Qc4-b4 6.h5-h6 Bf7-g6 7.Rh3-e3 Ne5-f7 8.Qd1-e2 Nf7xh6 9.Re1-c1
= (-0.21) Depth: 14 00:00:31 9290kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Rf1-e1 Nd7-e5 5.Qf3-d1 Qc4-b4 6.h5-h6 Bf7-g6 7.Rh3-e3 Ne5-f7 8.Qd1-e2 Nf7xh6 9.Re1-c1
= (-0.21) Depth: 14 00:00:36 11206kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-g2 a4-a3 5.Rh3-e3 a3-a2 6.Re3-e2 e7-e6 7.d5xe6 Bf7xe6 8.Re2-e1 Qc4-c2 9.Re1-e2 Qc2-b1
³ (-0.45) Depth: 15 00:00:54 18311kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-g2 a4-a3 5.Rh3-e3 a3-a2 6.Re3-e2 e7-e6 7.d5xe6 Bf7xe6 8.Re2-e1 Qc4-c2 9.Re1-e2 Qc2-b1
³ (-0.45) Depth: 15 00:01:01 20960kN
1...Rc7xc4
µ (-0.75) Depth: 16 00:02:05 46076kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-g2 a4-a3 5.Rh3-e3 Nd7-e5 6.Re3-e1 a3-a2 7.Re1-a1 b3-b2 8.Qg2xb2 Qc4xe4+ 9.Qb2-g2 Qe4xd5 10.Rf1-f5 Qd5xg2+ 11.Kh1xg2 Ne5xg4
µ (-1.15) Depth: 16 00:03:34 79944kN
1...Rc7xc4 2.Na3xc4 Rc8xc4 3.Bd3xc4 Qb4xc4 4.Qf3-g2 a4-a3 5.Rh3-e3 Nd7-e5 6.Re3-e1 a3-a2 7.Re1-a1 b3-b2 8.Qg2xb2 Qc4xe4+ 9.Qb2-g2 Qe4xd5 10.Rf1-f5 Qd5xg2+ 11.Kh1xg2 Ne5xg4
µ (-1.15) Depth: 16 00:03:40 82596kN

(, 13.09.2007)
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Dr.Wael Deeb
Posts: 9773
Joined: Wed Mar 08, 2006 8:44 pm
Location: Amman,Jordan

Re: A combination by Rybka

Post by Dr.Wael Deeb »

I agree with uri that the move is a positional issue for the chess engine rather than a tactical combination....
_No one can hit as hard as life.But it ain’t about how hard you can hit.It’s about how hard you can get hit and keep moving forward.How much you can take and keep moving forward….
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jdart
Posts: 4411
Joined: Fri Mar 10, 2006 5:23 am
Location: http://www.arasanchess.org

Re: A combination by Rybka

Post by jdart »

I agree an engine might select this initially for positional reasons, and not see it is winning, but if the engine gets a +1.5 or higher score, it is seeing the followup, too.

--Jon
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