Interesting passed pawns ending

[David Dahlem]

Two isolated outside passed pawns for Black and two isolated inside passed pawns for White.

[d]8/4R3/2n3k1/p1P4p/2K1P2r/6B1/8/8 b - - 0 60

Black exchanged rooks here, and it was all downhill from there. Here is the full game.

[Event "Mini Monsters - NoBook RR"]
[Site "?"]
[Date "2010.02.09"]
[Round "1"]
[White "Komodo 1.0"]
[Black "Critter 0.52a"]
[Result "1-0"]
[ECO "A00"]
[Opening "Benko Opening"]
[Time "17:50:29"]
[Variation "Reversed Alekhine"]
[TimeControl "40/300:40/300:40/300"]

1.g3 {+0.20/13} e5 {+0.25/15} 2.Nf3 {+0.02/14} e4 {+0.17/16} 3.Nh4 {+0.01/15} d5 {+0.25/15} 4.d3 {+0.07/14} Nf6 {+0.10/14} 5.dxe4 {+0.09/13} Nxe4 {+0.03/15} 6.Bg2 {-0.09/13} Be7 {+0.01/14} 7.O-O {+0.21/13} O-O {-0.01/15} 8.c4 {+0.14/14} c6 {+0.19/16} 9.cxd5 {+0.11/14} cxd5 {+0.12/16} 10.Nc3 {-0.01/14} Nxc3 {+0.24/16} 11.bxc3 {+0.21/11} Bxh4 {+0.17/16} 12.gxh4 {-0.01/11} Qxh4 {+0.14/16} 13.Qxd5 {+0.15/13} Nc6 {+0.15/15} 14.Rb1 {+0.07/12} h6 {+0.14/14} 15.Re1 {+0.03/13} Re8 {+0.32/14} 16.Ba3 {+0.07/12} Re5 {+0.15/13} 17.Qf3 {0.00/13} Qc4 {+0.57/15} 18.Qd3 {+0.15/12} Qxa2 {+0.63/15} 19.Bd6 {+0.12/13} Rh5 {+0.58/15} 20.Red1 {+0.09/12} Qe6 {+0.68/13} 21.Bg3 {+0.09/11} Qe7 {+0.71/14} 22.Be4 {+0.06/11} Bg4 {+0.65/13} 23.f3 {0.00/12} Bh3 {+0.53/13} 24.Qd6 {+0.02/12} Qe8 {+0.62/13} 25.Kf2 {+0.25/12} Qc8 {+0.15/14} 26.Rb2 {+0.27/13} Rg5 {+0.21/13} 27.Rdb1 {+0.45/14} Bf5 {-0.67/13} 28.Bxf5 {+0.23/15} Qxf5 {+0.10/14} 29.R2xb7 {+0.20/15} Rg6 {+0.09/14} 30.R1b5 {+0.25/14} Qxb5 {+0.07/14} 31.Rxb5 {+0.25/13} Rxd6 {+0.05/15} 32.Bxd6 {+0.26/12} a5 {+0.05/14} 33.Rb6 {+0.16/14} Rc8 {+0.05/14} 34.h4 {+0.27/13} g6 {+0.03/12} 35.Bf4 {+0.34/13} h5 {-0.01/13} 36.c4 {+0.30/14} f6 {-0.08/13} 37.c5 {+0.35/15} Kf7 {-0.36/14} 38.Ra6 {+0.40/15} Ke6 {0.00/14} 39.e4 {+0.51/15} Kd7 {-0.15/15} 40.Ke3 {+0.34/16} Re8 {-0.19/13} 41.Bg3 {+0.27/15} g5 {-0.16/18} 42.Rb6 {+0.36/16} gxh4 {-0.28/18} 43.Bxh4 {+0.27/15} f5 {-0.45/17} 44.Bg3 {+0.28/16} fxe4 {-0.66/17} 45.fxe4 {+0.39/16} Rg8 {-0.69/17} 46.Bd6 {+0.35/14} Rg1 {-0.63/16} 47.Rb7+ {+0.43/13} Ke6 {-0.60/16} 48.Rc7 {+0.51/14} Nb4 {-0.72/15} 49.Ke2 {+0.51/15} Kf6 {-0.55/16} 50.Rh7 {+0.46/14} Kg6 {-0.65/15} 51.Rh8 {+0.61/15} Rh1 {-0.70/14} 52.Ra8 {+0.62/13} Rh4 {-0.81/15} 53.Ke3 {+0.63/14} Nc2+ {-0.70/17} 54.Kd3 {+0.57/14} Nb4+ {-0.81/17} 55.Kd4 {+0.56/13} Kf6 {-0.81/16} 56.Rf8+ {+0.78/14} Ke6 {-1.27/16} 57.Re8+ {+0.92/15} Kf7 {-1.10/18} 58.Re7+ {+0.84/14} Kg6 {-1.22/16} 59.Kc4 {+0.96/14} Nc6 {-0.95/17} 60.Bg3 {+1.00/17} Nxe7 {-1.25/18} 61.Bxh4 {+1.36/14} Kf7 {-1.67/21} 62.Kb5 {+1.89/20} a4 {-1.72/20} 63.Kxa4 {+2.05/20} Ke6 {-1.71/21} 64.Kb5 {+2.25/22} Ng6 {-2.36/21} 65.Bg3 {+3.12/21} h4 {-2.21/21} 66.Bh2 {+3.18/21} Kd7 {-2.54/22} 67.c6+ {+4.02/23} Kd8 {-2.50/23} 68.Kb6 {+4.64/24} Kc8 {-2.58/25} 69.e5 {+4.69/24} Nf8 {-2.97/23} 70.Kc5 {+4.70/26} Ne6+ {-4.11/22} 71.Kd6 {+4.74/24} Nd4 {-4.18/22} 72.e6 {+4.84/24} Nf5+ {-3.76/21} 73.Kc5 {+4.57/23} Kd8 {-4.56/21} 74.c7+ {+4.86/23} Kc8 {-4.64/21} 75.Kd5 {+4.90/25} Ng7 {-7.93/19} 76.Kd6 {+6.33/21} Ne8+ {-9.49/18} 77.Kc6 {+10.28/17} Nf6 {-24.17/17} 78.e7 {+M16/19} Ne8 {-25.73/18} 79.Be5 {+M15/18} h3 {-80.68/17} 80.Bh2 {+M14/15} Nf6 {-80.76/17} {Black resigns} 1-0

[De Vos W]

New game
8/4R3/2n3k1/p1P4p/2K1P2r/6B1/8/8 b - - 0 1

Analysis by Rybka 4 w32:

On a slow Dual Core PC




1...Rg4 2.Re6+ Kf7 3.Rxc6 Rxg3 4.Rh6 Rg5 5.Ra6 Rg1 6.Rxa5 h4 7.Ra3 Ke6 8.Rh3 Rg4 9.Kd4 Rf4 10.Rh2 Rg4 11.Ra2 h3 12.Ra6+ Kd7 13.Rh6 Rg3 14.e5 Ra3 15.Kc4 Kc7 16.e6 Kc6 17.Kd4 Rb3 18.e7+ Kd7 19.Rh7
+/= (0.54) Depth: 26 00:02:08 290mN
1...Rg4 2.Re6+ Kf7 3.Rxc6 Rxg3 4.Rh6 Rg5 5.Ra6 Rg1 6.Rxa5 h4 7.Ra3 Ke6 8.Rh3 Rg4 9.Kd4 Rf4 10.Rh2 Rg4 11.Ra2 h3 12.Ra6+ Kd7 13.Rh6 Rg3 14.e5 Ra3 15.Kc4 Kc7 16.e6 Kc6 17.Kd4 Rb3 18.e7+ Kd7 19.Rh7
+/= (0.54) Depth: 26 00:02:24 325mN

( 10.02.2010)

[metax]

FEN: 8/4R3/2n3k1/p1P4p/2K1P2r/6B1/8/8 b - - 0 60

ChessMind:
14/36 00:37 12.079.948 326.000 +1,36 Th4g4 Te7e6+ Kg6f7 Te6xc6 Tg4xg3 Tc6h6 Tg3e3 Kc4d4 Te3h3 Th6a6 Th3a3

[Eelco de Groot]

Two isolated outside passed pawns for Black and two isolated inside passed pawns for White.

[d]8/4R3/2n3k1/p1P4p/2K1P2r/6B1/8/8 b - - 0 60

Black exchanged rooks here, and it was all downhill from there. Here is the full game.

Have not started the debug builds yet, I'm first trying if I can do something else about it. But for this position I made a special Rainbow Serpent version that gives a penalty for keeping a single Knight vs Bishop or Rook. I already had something like that before in an old version. It is a bit crude but it would work in this special case, not sure about the general case, or for instance what happens after an exchange of the two Rooks.

Probably the program should also know that these inside passers separated by a single file are strong, but that is only built in for cases when there are no more pieces on the board and the lone King has to stop one of these pawns by blocking it but can't take it because it would step out of the square of the other doing so. The rule is not watertight but should work in most cases. You would like a quick way to detect these two passed pawns, they are stronger than the outside passers I think, but I have not yet found some elegant piece of code Nice to see another example of this here David! There was a similar position about a week ago with two of those strong inside passed pawns separated by a single file.

This is just the code about the opponent Knight vs. your Rook or Bishop:

Code: Select all

		if (   pos.non_pawn_material(Them) == KnightValueMidgame
			&&(pos.non_pawn_material(Us)   == RookValueMidgame
			|| pos.non_pawn_material(Us)   == BishopValueMidgame))
			ebonus += Value(r * 30); // A lone Knight is not good at stopping passed pawns


        // Add the scores for this pawn to the middle game and endgame eval.
        ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), WeightPassedPawns);

    } // while
}

[d]8/4R3/2n3k1/p1P4p/2K1P2r/6B1/8/8 b - -

Engine: Rainbow Serpent 1.6.3s(dc) Build 100 (Athlon 2009 MHz, 128 MB)
by Tord Romstad, Marco Costalba, Joona Kiiski Modifications: Dann Corbit

1.00 0:00 -0.80 60...Rg4 (178) 1

2.00 0:00 -0.80 60...Rg4 61.Re6+ Kf7 (330) 3

3.00 0:00 -0.52 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3 (647) 5

4.00 0:00 -1.29 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 (1.310) 10

5.00 0:00 -1.25 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 (2.132) 17

6.00 0:00 -1.45 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg4 64.Rxh5 Rxe4+ 65.Kd5 (3.836) 30

7.00 0:00 -1.29 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.c6 Ke7 65.Kd4 a4
66.Rh7+ Kd6 67.c7 Rg8 68.e5+ Kc6 (18.930) 121

8.00 0:00 -1.81-- 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.c6 Ke7 65.Kd4 a4 66.e5 a3
67.Kd5 (36.616) 212

9.00 0:00 -1.85 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.Kd4 Ke7 65.Rh7+ Ke6
66.c6 Kd6 67.c7 Rg8 68.Rxh5 Kxc7
69.Rxa5 (46.893) 231

10.00 0:00 -1.77 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.Kd4 Ke7 65.Rh7+ Ke6
66.c6 a4 67.c7 Rg8 68.Rxh5 Rc8
69.Rh6+ Kd7 70.Rh7+ Ke6 (103.319) 347

11.00 0:00 -1.81 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.Kd4 Ke7 65.Ra6 Rg1
66.Rxa5 Rd1+ 67.Ke5 Kd7 68.Ra6 h4
69.Rh6 Rc1 (313.333) 514

12.00 0:00 -1.89 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.Kd4 Ke7 65.Ra6 Rg1
66.Rxa5 Rd1+ 67.Ke5 Kd7 68.Ra6 Rc1
69.Rd6+ Kc7 (415.102) 553

12.00 0:00 -1.61++ 60...Nxe7 61.Bxh4 Kf7 62.Kb5 Ng6
63.c6 Ke6 64.Be1 h4 65.c7 Kd7
66.Bxa5 h3 (477.879) 566

13.00 0:01 -1.45 60...Nxe7 61.Bxh4 Kf7 62.Kb5 Ke6
63.Kxa5 Ng6 64.Bg5 h4 65.c6 h3
66.Kb6 h2 67.c7 Kd7 68.Kb7 Ne7
69.Bxe7 h1Q 70.c8Q+ Kxe7 71.Qc5+ Kd7
72.Qf5+ Ke7 73.Qe5+ Kd7 (702.860) 616

14.01 0:01 -1.93-- 60...Nxe7 61.Bxh4 Kf7 62.Kb5 Ke6
63.Kxa5 Ng6 64.Bf2 h4 65.Kb6 h3
66.Bg3 Nh4 67.c6 Nf3 68.c7 Kd7
69.Kb7 (1.293.590) 689

14.02 0:02 -1.89 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.Kd4 Ke7 65.Ra6 h4
66.Rxa5 Rg1 67.Ra7+ Ke6 68.Ra6+ Kd7
69.Rd6+ Kc7 70.Rh6 Rd1+ 71.Ke5 Rh1
72.Kf4 Rc1 (1.594.508) 689

15.01 0:05 -1.61 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Rh6 Rg5 64.Kd4 Ke7 65.Ra6 Rg1
66.Rxa5 Rd1+ 67.Ke5 Kd7 68.Ra6 Rc1
69.Rd6+ Ke7 70.Rd5 h4 71.Kf4 Rc3
72.Rh5 (3.633.215) 694

16.01 0:11 -1.53 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Rxa5 Ke6 65.Ra8 Rc1+
66.Kb5 h4 67.Re8+ Kd7 68.Rh8 Rb1+
69.Kc4 Rc1+ 70.Kd4 Rd1+ 71.Ke5 Rc1
72.Rh7+ Kc6 73.Rxh4 Kxc5 (8.714.227) 727

17.01 0:16 -1.65 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Rxa5 Ke6 65.Ra8 Rc1+
66.Kb5 h4 67.Re8+ Kd7 68.Rh8 Rb1+
69.Kc4 Rc1+ 70.Kd4 Rd1+ 71.Ke5 Kc6
72.Rxh4 Kxc5 73.Rh7 Rd8 (11.895.357) 728

18.01 0:19 -1.65 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Rxa5 Ke6 65.Ra8 Rc1+
66.Kb5 h4 67.Re8+ Kd7 68.Rh8 Rb1+
69.Kc4 Rc1+ 70.Kd4 Rd1+ 71.Ke5 Kc6
72.Rxh4 Kxc5 73.Rh7 Rd8 (13.939.046) 733

19.01 0:29 -1.65 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Rxa5 Ke6 65.Ra8 Rc1+
66.Kb5 h4 67.Re8+ Kd7 68.Rh8 Rb1+
69.Kc4 Rc1+ 70.Kd4 Rd1+ 71.Ke5 Kc6
72.Rxh4 Kxc5 73.Rh7 Rd8 (21.695.823) 731

20.01 0:40 -1.65 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Rxa5 Ke6 65.Ra8 Rc1+
66.Kb5 h4 67.Re8+ Kd7 68.Rh8 Rb1+
69.Kc4 Rc1+ 70.Kd4 Rd1+ 71.Ke5 Rc1
72.Rh7+ Kc6 73.Rxh4 Rxc5+ (30.122.904) 741

21.01 1:18 -1.45++ 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Rxa5 Ke6 65.Ra8 h4 (58.745.582) 747

22.01 1:50 -1.49 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Kd5 Rd1+ 65.Ke5 Ke7
66.Ra7+ Kd8 67.Rxa5 Kd7 68.Ra6 Rc1
69.Rd6+ Ke7 70.Rd5 h4 71.Kd4 Rd1+
72.Ke3 Rc1 73.Rh5 Ke6 (84.547.431) 762

23.01 6:42 -1.17 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Kd5 Rd1+ 65.Ke5 Ke7
66.Ra7+ Kd8 67.Rxa5 Kd7 68.Ra6 h4
69.Rh6 Rh1 70.Kf4 h3 71.Kg3 Re1
72.Kf3 Rf1+ 73.Kg4 Re1 (298.602.856) 742

24.01 11:23 -1.29 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Kd5 Rd1+ 65.Ke5 Ke7
66.Ra7+ Kd8 67.Rxa5 Kd7 68.Ra7+ Kc6
69.Ra6+ Kxc5 70.Ra2 Rh1 71.Rc2+ Kb4
72.Kf6 Rf1+ 73.Ke6 Rh1 (505.826.906) 740

25.01 24:42 -1.25 60...Rg4 61.Re6+ Kf7 62.Rxc6 Rxg3
63.Ra6 Rg1 64.Kd5 Rd1+ 65.Ke5 h4
66.Rh6 a4 67.Rxh4 Rc1 68.Kd6 Rd1+
69.Kc7 a3 70.Rh2 Ra1 71.Kd6 Rd1+
72.Ke5 Rc1 73.Kd5 Rd1+ (1.098.937.350) 741

best move: Rh4-g4 time: 38:25.657 min n/s: 650.773 nodes: 1.500.450.242