Too high penalty?

[lech]

A time ago, I was watching a game (4’ + 2”).
[d]6k1/1p3qpp/5p2/b2r1b2/5B2/P4N2/1P2QPPP/R5K1 b - - 0 28
SF_171 (White) has a Pawn more and after 28…g5 29.b4 waiting for 29…Bd8. But opponent plays 29…Bxb4 and now SF is wrong 30.axb4 (better 30.Bxg5) gxf4 (=).
[d] 6k1/1p3q1p/5p2/3r1b2/1P3p2/5N2/4QPPP/R5K1 w - - 0 31
SF lost the pawn and all advantage. Why?
Probably, too high penalty, for doubled (x1) isolated (x2) pawns (f6 & f4), was one of possible reasons (40 + 40 + 23).
Now I found it (game 3): http://www.open-chess.org/viewtopic.php?f=3&t=351#p3089
[d] 8/8/8/3B1pk1/2K3p1/5nP1/4RP2/5r2 w - -
SF 1.8 plays 1.Bxf3 ?? gxf3 -+ Again doubled isolated pawns.

[Ralph Stoesser]

The second position is no good example for possibly too high double/isolated pawn penalty. As long as the engine does not see that Bxf3 loses material and the game, she will play it regardless how high the double/isolated pawn penalty is. Apart from this SF 1.8 sees very fast that Bxf3 loses. This blunder can only be played under heavy time pressure.

[lech]

I found a solution.
The following modern algorithm_of_weak_pawns is short and simple. It based at mobility and safety, fundament properties of each piece, pawns too.
A pawn which is not mobile “(blocked || controlled) && !(pos.attacks_from<PAWN>(s, Us) & theirPawns)” is susceptible to attack (if “!chain”). It needs to say goodbye: candidate, double, isolated, backward and opposed pawns.
It should work better with deep and aggressive pruning.

Code: Select all

template<Color Us>
Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
                                    Bitboard theirPawns, PawnInfo* pi) const {
// added 3 variables:
Value penalty_midgame = 25;
Value penalty_endgame = 40;
Score penalty = make_score(penalty_midgame, penalty_endgame);
      
// changes from the following line to the end of function
b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 1));
chain = ourPawns & neighboring_files_bb(f) & b;
passed  = !(theirPawns & passed_pawn_mask(Us, s)) && !(ourPawns & squares_in_front_of(Us, s));
blocked = (ourPawns | theirPawns) & squares_in_front_of(Us, s) & rank_bb(r + (Us == WHITE ? 1 : -1));
controlled  = pos.attacks_from<PAWN>(s + pawn_push(Us), Us) & theirPawns);
weak = !chain && (blocked || controlled) && !(pos.attacks_from<PAWN>(s, Us) & theirPawns);  
if (weak)
value -= penalty; 
if (passed)
          set_bit(&(pi->passedPawns), s);
}
return value;
}

[lech]

The first game is won by the new version.

Code: Select all

[Event "Computer chess game"]
[Site ""]
[Date "2010.07.09"]
[Round "?"]
[White "Sfx"]
[Black "Sf"]
[Result "*"]
[ECO "A40"]
[Opening "Queen's Pawn"]
[Time "16:36:25"]
[Variation "Bozo-Indian Defence, Four Pawns Attack"]
[TimeControl "180+2"]
[Termination "normal"]
[PlyCount "148"]
[WhiteType "program"]
[BlackType "program"]

1. e4 {(e2e4 Nb8c6 Ng1f3 Ng8f6 Nb1c3 e7e5 Bf1b5 Bf8d6 OO Nc6d4 d2d3 OO
Bc1g5) +0.36/12 12} Nc6 {(Nb8c6 Nb1c3 Ng8f6 Ng1f3 e7e5 Bf1b5 Bf8d6 OO OO
d2d4 e5xd4 Nf3xd4 a7a6) -0.36/11 6} 2. d4 {(d2d4 e7e6 Ng1f3 d7d5 e4xd5
e6xd5 Bf1d3 Ng8f6 OO Bf8e7 Nb1c3 OO Bc1f4 Bc8e6) +0.52/12 14} Nf6 {(Ng8f6
Nb1c3 e7e6 e4e5 Nf6d5 Nc3xd5 e6xd5 Ng1f3 Bf8e7 Bf1b5 OO OO d7d6 Bc1f4
Bc8f5) -0.44/11 12} 3. d5 {(d4d5 Nc6b8 Nb1c3 e7e6 d5xe6 d7xe6 Qd1xd8+
Ke8xd8 Bc1f4 Nb8d7 OOO Bf8c5 Ng1f3 Bc5xf2 Bf1b5) +1.05/10 5} Ne5 {(Nc6e5
Ng1f3 Ne5xf3+ Qd1xf3 e7e6 Nb1c3 e6xd5 e4xd5 Bf8c5 Bc1e3 Bc5xe3 Qf3xe3+
Qd8e7) -0.36/10 5} 4. f4 {(f2f4 Ne5g6 e4e5 Nf6e4 Bf1d3 Ne4c5 Ng1f3 Nc5xd3+
c2xd3 e7e6 d5xe6 Bf8b4+ Bc1d2 Bb4xd2+ Ke1xd2 Ng6xf4) +0.28/9 12} Ng6
{(Ne5g6 e4e5 Nf6e4 Qd1d4 f7f5 Nb1c3 c7c5 d5xc6/ep d7xc6 Ng1f3 Qd8xd4 Nf3xd4
e7e6) -0.08/11 10} 5. e5 {(e4e5 Nf6g8 Ng1f3 e7e6 Nb1c3 Ng8h6 Nc3e4 Nh6g4
Nf3g5 f7f5 d5xe6 f5xe4 Qd1xg4) +1.01/10 9} Ne4 {(Nf6e4 f4f5 c7c6 f5xg6
h7xg6 Nb1c3 Ne4g3 h2xg3 Rh8xh1 Ng1f3 Qd8b6 Qd1d4 c6xd5 Qd4xb6 a7xb6 Nc3xd5)
-0.80/10 10} 6. f5 {(f4f5 Ng6xe5 Qd1d4 Ne4f6 Qd4xe5 d7d6 Qe5d4 c7c6 d5xc6
b7xc6) +1.69/9 5} c6 {(c7c6 f5xg6 h7xg6 Qd1f3 c6xd5 Nb1c3 Qd8a5) -1.05/11
10} 7. fxg6 {(f5xg6 h7xg6 Qd1d3 c6xd5 Nb1c3 Ne4xc3 b2xc3 e7e6 Ke1d1 Bf8c5
Ng1f3 b7b5 Bc1g5 Qd8a5) +1.93/10 8} hxg6 {(h7xg6 Qd1d3 c6xd5 Nb1c3 Rh8h5
Bf1e2 Rh5xe5 Ng1f3 Re5e6 Nc3xd5 Ne4c5) -1.81/9 5} 8. Qd3 {(Qd1d3 c6xd5)
+2.02/12 11} Qa5+ {(Qd8a5+ Nb1c3 Ne4xc3 Qd3xc3 Qa5xc3+ b2xc3 c6xd5 Bc1e3
e7e6 Ng1f3 d7d6 Ke1d2) -2.02/11 12} 9. Nc3 {(Nb1c3 Ne4xc3 b2xc3 c6xd5 Ng1f3
e7e6 Bc1d2 Bf8a3 c3c4 Qa5c5 Ra1b1 d5xc4 Qd3xc4) +2.02/11 6} Nxc3 {(Ne4xc3
Qd3xc3 Qa5xc3+ b2xc3 c6xd5 Bc1e3 b7b6 OOO Bc8b7 Ng1f3 Ra8c8 Kc1b2 e7e6
Bf1b5 Bf8a3+ Kb2b3 a7a6 Bb5d3 Ba3c5 Be3xc5 Rc8xc5) -1.89/12 9} 10. Qxc3
{(Qd3xc3 Qa5xd5 Ng1f3 d7d6 Bc1e3 Bc8e6 Bf1d3 d6xe5 Qc3xe5 Qd5xe5 Nf3xe5
Rh8h5 Ne5xg6 f7xg6 Bd3xg6+ Be6f7 Bg6xh5 Bf7xh5) +2.18/11 8} Qxc3+ {(Qa5xc3+
b2xc3 c6xd5 Ng1f3 b7b6 Bc1e3 Bc8b7 OOO Ra8c8 Kc1b2 e7e6 Bf1b5 Bf8a3+ Kb2b3
a7a6 Bb5d3 Ba3c5 Be3xc5 Rc8xc5) -1.93/12 5} 11. bxc3 {(b2xc3 c6xd5 Bc1e3
e7e6 Ke1d2 b7b6 Ng1f3 Bf8c5 Bf1b5 Bc5xe3+ Kd2xe3 Bc8b7) +2.38/9 0} cxd5
{(c6xd5 Ng1f3 e7e6 Bc1e3 d7d6 Ke1d2 Bc8d7 Ra1b1 b7b6 Bf1e2 Bf8e7 Be3d4
Ke8f8 c3c4 d6xe5 Nf3xe5 Be7g5+ Bd4e3) -1.85/13 9} 12. Nf3 {(Ng1f3 e7e6
Bc1e3 b7b6 Ke1d2 Bc8b7 Ra1b1 Ra8c8 h2h3 Bf8c5 Be3xc5 Rc8xc5 Bf1b5 Ke8e7)
+2.18/13 6} f6 {(f7f6 Bc1e3 g6g5 OOO g5g4 Nf3e1 f6xe5 Rd1xd5 d7d6 Bf1e2
Bc8d7 Kc1b1 Bd7e6) -1.77/12 10} 13. Be3 {(Bc1e3 g6g5 e5xf6 g7xf6 OOO g5g4
Nf3e1 e7e6 Ne1d3) +2.26/8 4} g5 {(g6g5 OOO e7e6 e5xf6 g7xf6 Bf1b5 g5g4
Nf3d2 Bf8d6 h2h4 a7a6 Bb5d3) -1.85/11 7} 14. exf6 {(e5xf6 g7xf6 OOO b7b6
Bf1e2 e7e6 h2h4 g5xh4 Kc1b2 Bf8c5 Nf3d4) +2.46/10 4} gxf6 {(g7xf6 Nf3d4
a7a6 Bf1e2 e7e5 Nd4f5 d7d6 OO Bc8e6 Be2g4 Ra8c8 Nf5xd6+ Bf8xd6 Bg4xe6
Rc8xc3) -1.69/10 6} 15. O-O-O {(OOO e7e6 h2h4 g5xh4 Kc1b2 b7b6 Bf1b5 Bc8b7
Nf3xh4 Bf8c5 Be3f4) +2.38/11 10} e6 {(e7e6 Bf1e2 b7b6 h2h4 g5xh4 Nf3xh4
Ke8f7 Nh4f3 Bf8a3+ Kc1b1 Bc8b7) -1.93/10 13} 16. h4 {(h2h4 b7b6 h4h5 Bc8b7
Bf1d3 Ra8c8 Kc1b2 e6e5 Bd3f5 Bf8a3+ Kb2b3 e5e4) +2.50/10 4} gxh4 {(g5xh4
g2g3 h4h3 Rh1xh3 Rh8xh3 Bf1xh3 Bf8d6 g3g4 b7b6 Kc1b2) -1.85/9 3} 17. Nxh4
{(Nf3xh4 b7b6 Bf1d3 Bc8b7 Nh4g6 Rh8xh1 Rd1xh1 Bf8a3+ Kc1d2 e6e5 Rh1h7
Ra8c8) +2.30/10 11} b6 {(b7b6 Bf1d3 Rh8g8 Nh4g6 Bf8d6 Kc1b1 Bc8b7 Rh1h7
f6f5 Ng6f4 Bd6xf4 Be3xf4 Rg8xg2) -1.65/10 9} 18. Bd3 {(Bf1d3 Bf8c5 Kc1d2
Bc5xe3+ Kd2xe3 Bc8b7 Nh4g6 Rh8g8 Ke3d2 Ke8f7 Rh1h7+ Rg8g7 Rd1h1 Ra8c8)
+2.22/10 4} Bd6 {(Bf8d6 Nh4g6 Rh8g8 Kc1b1 Bc8b7 Rh1h7 f6f5 Ng6f4 Bd6xf4
Be3xf4 Rg8xg2) -1.65/10 4} 19. Kb2 {(Kc1b2 Rh8g8 Rd1f1 Rg8g3 Be3d4 f6f5
Bd3b5 Ke8d8 Bd4f6+ Kd8c7) +2.46/9 7} Bc5 {(Bd6c5 Bd3g6+ Ke8d8 Be3xc5 b6xc5
Rd1f1 Ra8b8+ Kb2c1 f6f5 Nh4f3 Rh8xh1 Rf1xh1 Bc8a6 Rh1h8+ Kd8c7 Rh8xb8
Kc7xb8) -1.33/10 8} 20. Bd4 {(Be3d4 Ke8f7 Rd1f1 Bc5xd4 c3xd4 Bc8b7 Nh4f3
Rh8xh1 Rf1xh1 Ra8g8 Rh1h7+ Rg8g7 Rh7xg7+ Kf7xg7 Kb2c3 Kg7f7) +2.26/10 5} e5
{(e6e5 Bd4xc5 b6xc5 Nh4f5 Ra8b8+ Kb2c1 Rh8xh1 Rd1xh1 Ke8d8 Rh1h8+ Kd8c7
Kc1d2 Rb8b6 Bd3e2 Bc8b7 Rh8h7 d5d4 g2g4) -1.65/10 6} 21. Bg6+ {(Bd3g6+
Ke8d8 Bd4xc5 b6xc5 Rd1xd5 Ra8b8+ Kb2c1 Bc8b7 Rd5d1 Bb7c6 Rd1f1 Bc6d5 Kc1d2
Bd5xa2 Bg6e4 Ba2c4 Rf1xf6 Kd8e7 Rf6f3) +2.02/10 6} Kd8 {(Ke8d8 Bd4xc5 b6xc5
Rd1xd5 Bc8b7 Rd5d1 Ra8b8 Kb2a3 Bb7c6 Nh4f3 Rh8xh1 Rd1xh1 Kd8e7 Rh1d1 Rb8h8)
-1.41/10 3} 22. Bxc5 {(Bd4xc5 b6xc5 Rd1xd5 Ra8b8+ Kb2c1 Bc8b7 Rd5d1 Kd8c7
Bg6f7 Bb7c6 Rd1f1 Bc6e4 Kc1d2 Rb8b6) +1.85/11 3} bxc5 {(b6xc5 Rd1xd5 Bc8b7
Rd5d1 Ra8b8 Kb2a3 Kd8c7 c3c4 Rb8g8 Bg6f5) -1.45/8 0} 23. Rxd5 {(Rd1xd5
Ra8b8+ Kb2c1 Bc8b7 Rd5d1 Bb7c6 Rd1f1 Bc6d5 Kc1d2 Bd5xa2 Bg6e4 Rb8b1 Rf1xb1
Ba2xb1 Rh1xb1 Rh8xh4) +2.02/11 4} Bb7 {(Bc8b7 Rd5d1 Ra8b8 Kb2c1 Kd8c7 Bg6f5
Bb7c6 Kc1d2 Rh8h5 g2g4 Rh5h8 Rh1h3 d7d5) -1.33/11 3} 24. Rdd1 {(Rd5d1 Ra8b8
Kb2c1 Kd8c7 Rh1h2 Rb8g8 Bg6f5 Bb7c6 Rh2h3 Rg8g5 g2g4 e5e4 Kc1d2 d7d5 Kd2e3)
+1.81/11 9} Rb8 {(Ra8b8 Kb2c1 Kd8c7 Bg6f5 d7d6 Nh4f3 e5e4 Rh1xh8 Rb8xh8
Nf3d2 d6d5 Nd2b3) -1.49/11 5} 25. Kc1 {(Kb2c1 Kd8c7 Bg6f5 d7d6 Rh1h3 Rb8g8
c3c4 Bb7c6 g2g4 Bc6d7 Kc1b2 Bd7xf5 g4xf5) +1.97/11 3} Kc7 {(Kd8c7 Bg6f5
Bb7c6 Rh1h3 d7d5 Nh4g6 Rh8xh3 g2xh3 Kc7d6 h3h4 d5d4 Kc1d2 Bc6d5 c3xd4
c5xd4) -1.37/11 2} 26. Bf5 {(Bg6f5 d7d6 Rh1h3 Rb8g8 c3c4 Bb7c6 Bf5e6 Bc6d7
Be6xg8 Bd7xh3 g2xh3 Rh8xg8) +2.06/11 11} Bc6 {(Bb7c6 Nh4g6) -2.06/12 19}
27. Ng6 {(Nh4g6 Rh8xh1 Rd1xh1 Bc6xg2 Rh1h7 Rb8d8 Rh7f7 Bg2d5 Rf7xf6 d7d6
Bf5e6 Bd5xe6 Rf6xe6) +1.77/10 5} Rxh1 {(Rh8xh1 Rd1xh1 Rb8d8 Rh1h7 Bc6d5
a2a3 Bd5g8 Rh7h2 Bg8e6 Bf5xe6 d7xe6 Rh2h7+ Rd8d7 Rh7xd7+ Kc7xd7 Kc1d2)
-2.10/11 4} 28. Rxh1 {(Rd1xh1 Bc6xg2 Rh1h7 Rb8d8 Rh7f7 Bg2d5 Rf7xf6 d7d6
Bf5e6 Bd5xe6) +1.69/8 0} Rd8 {(Rb8d8 Rh1h7 Bc6xg2 Rh7f7 Bg2d5 Rf7xf6 d7d6
a2a3 Rd8e8 Kc1d2 a7a5 Rf6f8 Re8xf8 Ng6xf8 Kc7c6 Kd2e3) -2.02/11 2} 29. Rh2
{(Rh1h2 Bc6d5 a2a3 Kc7d6 Kc1d2 Bd5e6 g2g4 Rd8g8 Rh2h7 a7a5 Kd2e3 Rg8b8
Ke3e4 Be6d5+ Ke4e3) +2.42/11 3} Bd5 {(Bc6d5 a2a4 Kc7d6 Kc1d2 Bd5e6 g2g4
Be6xf5 g4xf5 Kd6d5 Rh2h4 Kd5d6 Rh4h7 Rd8g8 Kd2e3) -2.22/10 7} 30. a3 {(a2a3
Bd5e6 g2g4 Rd8g8 Rh2h7 Kc7d6 Kc1d2 a7a5 Kd2e3 Rg8b8 c3c4 Rb8b2 Bf5xe6 d7xe6
Ke3d3) +2.54/12 7} Bf7 {(Bd5f7 Kc1d2 Kc7d6 Rh2h7 Bf7e6 g2g4 Rd8g8 Kd2e3
Be6xf5 g4xf5 Rg8b8) -2.22/9 3} 31. Rh6 {(Rh2h6 Bf7c4 Kc1d2 Kc7d6 Ng6h4
Kd6e7 Rh6h7+ Ke7d6 Nh4f3 Bc4e6 Bf5xe6 Kd6xe6) +2.94/10 5} Be6 {(Bf7e6
Bf5xe6 d7xe6 Ng6h4 Rd8f8 Kc1d2 Kc7d6 Kd2e3 Kd6d5 Rh6h7 Rf8g8 Rh7xa7 Rg8g3+
Ke3d2) -2.50/9 3} 32. Nh4 {(Ng6h4 Rd8f8 Kc1d2 a7a5 g2g4 Kc7d6 Kd2e3 c5c4
Nh4f3 Be6xf5 g4xf5 Kd6d5 Nf3d2) +2.90/11 3} Rf8 {(Rd8f8 Bf5xe6 d7xe6 Kc1d2
Kc7d6 Kd2e3 Kd6d5 Nh4f3 Kd5c4 Nf3d2+ Kc4xc3 Nd2e4+ Kc3xc2 Ne4xc5) -2.38/10
4} 33. Kd2 {(Kc1d2 Kc7c6 g2g4 Kc6b5 Kd2d3 Kb5a4 Rh6h7 c5c4+ Kd3e3 Ka4xa3
Bf5xe6 d7xe6 Rh7xa7+ Ka3b2) +2.90/10 3} Kd6 {(Kc7d6 Bf5d3 c5c4 Bd3f5 Kd6c5
Kd2e3 Be6xf5 Nh4xf5 Rf8g8 g2g3) -2.22/9 2} 34. Kd3 {(Kd2d3 c5c4+ Kd3e3
Kd6d5 g2g4 Kd5c5 Nh4f3 Be6xf5 g4xf5 d7d5 Rh6h7 a7a5) +2.74/9 4} c4+ {(c5c4+
Kd3e3 Kd6d5 g2g4 Kd5d6 Nh4f3 Kd6d5 Nf3d2 Be6xf5 g4xf5 d7d6) -2.58/8 2} 35.
Ke4 {(Kd3e4 a7a6 Nh4f3 Be6d5+ Ke4e3 Bd5e6 Bf5xe6 d7xe6 g2g4) +2.98/11 4}
Bd5+ {(Be6d5+ Ke4e3 Bd5c6 Nh4f3 Kd6c5 Rh6h7 Rf8g8 g2g4 a7a6 Rh7h6 Rg8f8)
-2.58/9 2} 36. Ke3 {(Ke4e3 Bd5e6 g2g4 Kd6c5 Nh4f3 Be6xf5 g4xf5 d7d5)
+2.94/6 0} Be6 {(Bd5e6 g2g4 a7a5 Bf5xe6 Kd6xe6 Nh4f3 Ke6d5 Rh6h7 Kd5e6
Ke3e4 d7d5+ Ke4e3) -2.46/10 2} 37. g4 {(g2g4 a7a6 Bf5xe6 d7xe6 Nh4f3 Rf8g8
Rh6xf6 Rg8xg4 Rf6f8 Rg4g2 Rf8d8+ Kd6e7 Rd8d2) +2.94/11 2} a5 {(a7a5 Bf5xe6
d7xe6 Nh4f3 Kd6d5 Rh6h1 Rf8g8 Rh1d1+ Kd5c5 g4g5 f6f5 Nf3xe5 Rg8xg5)
-2.94/10 6} 38. Bxe6 {(Bf5xe6 d7xe6 Nh4f3 Rf8g8 g4g5 f6f5 g5g6 Kd6d5 Nf3g5
Rg8g7 Ng5f7 a5a4 Ke3f3) +3.15/10 3} Kxe6 {(Kd6xe6 Nh4f5 Ke6d5 Nf5g7 Kd5d6
g4g5 Kd6e7 Ke3e4 f6xg5 Ke4xe5 Ke7f7 Ng7f5) -3.19/10 5} 39. Nf5 {(Nh4f5
Ke6d5 Rh6h7 Rf8d8 Ke3f3 a5a4 Rh7f7 Kd5e6 Rf7e7+ Ke6d5 Re7h7 d7d6) +3.27/9
2} Rc8 {(Rf8c8 Ke3f3 Rc8f8 Rh6h7 Rf8f7 Rh7xf7 Ke6xf7 Nf5d6+ Kf7e6 Nd6xc4
a5a4 Nc4b6) -3.23/10 2} 40. Ng7+ {(Nf5g7+ Ke6f7 Ng7h5 Rc8c6 Rh6h7+ Kf7e6
Nh5g7+ Ke6d5 Rh7h6 a5a4 Ng7e8 f6f5 g4g5 Rc6c8 Ne8f6+) +3.63/9 2} Kf7
{(Ke6f7 Ng7h5 Rc8c6 Rh6h7+ Kf7e6 Nh5g7+ Ke6d5 Rh7h6 f6f5 Ng7xf5 Rc6xh6
Nf5xh6 d7d6) -3.27/9 1} 41. Nh5 {(Ng7h5 Rc8c6 Nh5g3 Rc6c7 a3a4 Kf7e7 Ng3f5+
Ke7e6 Rh6h8 Rc7a7 Rh8b8 d7d6) +3.51/10 2} Rc6 {(Rc8c6 Rh6h7+ Kf7e6 Nh5g7+
Ke6d5 Rh7h6 a5a4 Ng7h5 f6f5 g4g5 d7d6 Nh5f6+ Kd5e6 Nf6e4+ Ke6d5 Ne4d2)
-3.27/10 1} 42. Rh7+ {(Rh6h7+ Kf7e6 Nh5g7+ Ke6d5 Rh7h6 a5a4 Ng7e8 f6f5 g4g5
Rc6c8 Ne8f6+ Kd5e6 Nf6e4+ Ke6e7 Ne4d6) +4.00/11 2} Ke6 {(Kf7e6 a3a4 Rc6c8
Rh7h6 Rc8f8 g4g5 Ke6f5 Rh6xf6+ Rf8xf6 Nh5xf6 Kf5xg5 Nf6xd7 Kg5f5 Nd7c5)
-3.91/11 5} 43. Ng7+ {(Nh5g7+ Ke6d5 Rh7h6 f6f5 Ng7xf5 Rc6xh6 Nf5xh6 Kd5e6
g4g5 d7d5 Ke3f3) +4.88/11 8} Kd5 {(Ke6d5 Rh7h1 Kd5d6 Rh1h6 Kd6e7 Rh6h7
Ke7d6 Ng7f5+ Kd6c7 Nf5e7 Rc6e6 Ne7d5+ Kc7d6) -3.75/10 2} 44. Rh6 {(Rh7h6
Rc6c8 Ng7h5 Kd5e6 Rh6xf6+ Ke6e7 Rf6b6 Rc8f8 Ke3e4 Rf8f2 Ke4xe5 Rf2xc2)
+4.92/11 2} a4 {(a5a4 Ng7h5 f6f5 g4g5 Rc6c8 Nh5f6+ Kd5e6 Ke3f3 Ke6e7 Nf6d5+
Ke7f7 Rh6f6+ Kf7g7 Rf6xf5 d7d6) -4.24/10 2} 45. Ne8 {(Ng7e8 f6f5 g4g5 Rc6c8
Rh6h8 Rc8c6 Ne8f6+ Rc6xf6 g5xf6 Kd5e6 Rh8c8 f5f4+ Ke3f3 Ke6xf6 Rc8xc4 Kf6f5
Rc4xa4 d7d5) +5.53/12 4} f5 {(f6f5 g4g5 Rc6c8 Ne8f6+ Kd5e6 Ke3f3 Rc8b8
Nf6g4+ Ke6d5 Ng4e3+ Kd5c5 Ne3xf5 Rb8f8) -4.40/9 1} 46. g5 {(g4g5 Rc6c8
Rh6h8 Rc8c6 Ne8f6+ Rc6xf6 g5xf6 Kd5e6 Rh8d8 d7d6 f6f7 Ke6xf7 Rd8xd6 Kf7e7
Rd6c6 f5f4+ Ke3e4) +5.41/9 1} Rc8 {(Rc6c8 Ne8f6+ Kd5e6 Ke3f3 Rc8b8 Nf6g4+
Ke6d5 Ng4e3+ Kd5c5 Ne3xf5 Rb8b2 g5g6 Rb2xc2 g6g7 Rc2xc3+ Kf3e4) -4.84/10 1}
47. Rh8 {(Rh6h8 Rc8c6 Ne8f6+ Rc6xf6 g5xf6 Kd5e6 Rh8d8 Ke6xf6 Rd8xd7 Kf6e6
Rd7a7 Ke6d5 Ra7a5+ Kd5e6 Ra5xa4) +5.89/11 2} f4+ {(f5f4+ Ke3f3 Rc8c6 Rh8h6
Rc6c8 Ne8f6+ Kd5e6 Kf3e4 f4f3 Nf6d5+ Ke6f7 Rh6f6+ Kf7g7 Rf6xf3 d7d6)
-5.29/9 2} 48. Kf3 {(Ke3f3 Rc8c6 Ne8f6+ Kd5e6 Rh8e8+ Ke6f5 Nf6xd7 Kf5xg5
Re8xe5+ Kg5h6 Re5e4 Rc6d6 Nd7e5 Rd6d2 Re4xc4 Kh6g5 Rc4xf4 Rd2xc2) +6.02/11
2} Rc6 {(Rc8c6 Rh8h6 Rc6c8 Ne8f6+ Kd5e6 Kf3e4 d7d6 Nf6e8+ Ke6e7 Ne8xd6
Rc8g8 Ke4xe5 Rg8xg5+ Ke5xf4) -5.57/10 1} 49. Nf6+ {(Ne8f6+ Kd5e6 Rh8e8+
Ke6f5 Nf6xd7 Kf5xg5 Re8xe5+ Kg5h6 Re5e4 Rc6d6 Nd7e5 Rd6d2 Kf3xf4 Rd2f2+
Kf4e3 Rf2xc2 Re4xc4 Kh6g5 Rc4g4+ Kg5f5) +6.02/11 2} Ke6 {(Kd5e6 Rh8e8+
Ke6f5 Nf6xd7 Kf5xg5 Re8xe5+ Kg5h4 Nd7c5 Rc6g6 Re5e8 Rg6g3+ Kf3xf4 Rg3g4+
Kf4e3 Rg4g2 Re8e4+ Kh4g5 Nc5xa4 Rg2xc2 Re4xc4) -5.89/10 1} 50. Re8+
{(Rh8e8+ Ke6f5 Nf6xd7 Kf5xg5 Re8xe5+ Kg5g6 Kf3xf4 Rc6d6 Re5g5+ Kg6h6 Nd7e5
Rd6d2 Ne5xc4 Rd2f2+ Kf4e3 Rf2xc2) +6.30/10 1} Kf5 {(Ke6f5 Nf6xd7 Kf5xg5
Re8xe5+ Kg5g6 Kf3xf4 Rc6d6 Re5g5+ Kg6h6 Nd7e5 Rd6d2 Rg5g3 Rd2xc2 Ne5xc4
Kh6h5 Rg3g5+ Kh5h4) -5.97/11 2} 51. Nxd7 {(Nf6xd7 Kf5xg5 Re8xe5+ Kg5g6
Kf3xf4 Rc6d6 Re5g5+ Kg6h6 Nd7e5 Rd6d2 Ne5g4+ Kh6h7 Ng4e3 Rd2f2+ Kf4g3 Rf2e2
Kg3f3 Re2h2 Kf3e4 Kh7h6) +6.34/10 1} Kxg5 {(Kf5xg5 Re8xe5+ Kg5h6 Re5e4
Rc6d6 Nd7e5 Rd6d2 Kf3xf4 Rd2xc2 Re4xc4 Kh6h5) -5.93/10 1} 52. Rxe5+
{(Re8xe5+ Kg5h6 Kf3xf4 Rc6d6 Nd7c5 Rd6d2 Re5e4 Rd2xc2 Re4xc4 Kh6g6 Nc5e4
Rc2e2 Rc4xa4) +6.58/10 3} Kh6 {(Kg5h6 Re5e4 Rc6d6 Re4d4 Rd6e6 Rd4xf4 Kh6g5)
-6.22/11 3} 53. Kxf4 {(Kf3xf4 Rc6d6 Nd7c5 Rd6d1 Re5e6+ Kh6g7 Re6a6 Rd1d2
Ra6xa4 Rd2xc2 Ra4xc4 Kg7f6 Nc5e4+ Kf6e6 Rc4c6+ Ke6d5) +6.70/11 3} Rd6
{(Rc6d6 Nd7c5 Rd6d1 Re5e6+ Kh6g7 Re6a6 Rd1d2 Ra6xa4 Rd2xc2 Ra4xc4 Kg7g6)
-6.26/9 1} 54. Nc5 {(Nd7c5 Rd6d2 Re5e4 Rd2f2+ Kf4e5 Rf2xc2 Re4xc4 Kh6g6
Nc5e4 Rc2b2 Rc4xa4 Rb2b5+ Ke5d4) +6.86/11 2} Rd1 {(Rd6d1 Re5e6+ Kh6h5 Re6a6
Rd1f1+ Kf4e5 Rf1f3 Ke5d4 Rf3f4+ Kd4d5 Kh5g4 Ra6xa4) -6.38/9 2} 55. Re6+
{(Re5e6+ Kh6g7) +7.03/9 2} Kh5 {(Kh6h5 Re6a6) -6.62/10 2} 56. Ra6 {(Re6a6
Rd1c1 Ra6xa4 Rc1xc2 Ra4xc4 Rc2a2 Rc4a4 Ra2c2 c3c4) +7.07/9 1} Rc1 {(Rd1c1
Ra6xa4) -6.78/10 2} 57. Rxa4 {(Ra6xa4 Rc1f1+ Kf4e5 Rf1a1 Ke5d5 Ra1a2 Nc5e6
Ra2xc2 Ra4xc4 Rc2f2 a3a4 Rf2f5+ Kd5d6) +7.43/9 1} Ra1 {(Rc1a1 Kf4e5 Kh5g6
Ke5d4 Ra1g1 Kd4xc4 Rg1g2 Kc4d3 Kg6f5) -7.11/9 2} 58. Ne4 {(Nc5e4 Kh5g6
Ra4a6+ Kg6g7) +7.59/9 2} Kg6 {(Kh5g6 Ra4a6+) -7.27/8 2} 59. Ra6+ {(Ra4a6+
Kg6g7 a3a4 Ra1a2 a4a5 Ra2xc2 Ra6f6 Rc2a2 a5a6 Ra2a5 Kf4e3) +7.91/9 2} Kf7
{(Kg6f7 Ne4d6+ Kf7e6 Nd6xc4+ Ke6d5 Nc4e3+ Kd5c5 Ra6a5+ Kc5c6 a3a4 Ra1e1
Ra5h5) -7.43/9 1} 60. Nd6+ {(Ne4d6+ Kf7e6 Nd6xc4+ Ke6d5 Nc4e3+ Kd5c5 Ra6a5+
Kc5b6 Ra5h5 Kb6c6 Ne3c4) +8.16/7 1} Ke6 {(Kf7e6 Nd6xc4+ Ke6d5 Nc4e3+ Kd5c5
Ra6a5+ Kc5c6 c3c4 Ra1h1 Ne3f5 Rh1f1+ Kf4e5 Kc6c7) -7.55/8 1} 61. Nxc4+
{(Nd6xc4+ Ke6d5 Nc4e3+ Kd5c5 c3c4 Ra1h1 Ra6a5+ Kc5c6 Kf4e4 Rh1h4+ Ke4e5
Rh4h3 Ne3d5) +8.40/8 1} Kd5 {(Ke6d5 Nc4e3+ Kd5c5 Ra6a5+ Kc5c6 c3c4 Ra1h1
Ne3f5 Rh1f1+ Kf4e4 Rf1e1+ Nf5e3 Re1e2) -7.59/9 1} 62. Ne3+ {(Nc4e3+ Kd5c5
c3c4 Ra1h1 Ra6a5+ Kc5c6 Ne3f5 Rh1f1+ Kf4e4 Rf1e1+ Nf5e3 Re1h1 Ra5d5 Rh1h4+
Ke4d3 Rh4h3 a3a4) +8.40/9 1} Kc5 {(Kd5c5 c3c4 Ra1h1 Ra6a5+ Kc5c6 Ra5g5
Rh1e1) -7.51/6 0} 63. c4 {(c3c4 Ra1h1 Ra6a5+ Kc5c6 Ne3f5 Rh1d1 a3a4 Rd1f1+
Kf4e4 Rf1e1+ Nf5e3 Re1a1 Ne3d5 Ra1e1+ Ke4d4) +8.60/9 2} Rh1 {(Ra1h1 Ra6a5+
Kc5c6 Ne3f5 Rh1f1+ Kf4e4 Rf1e1+ Nf5e3 Re1h1 Ra5f5 Rh1h4+ Rf5f4 Rh4h3)
-7.63/9 1} 64. Ra5+ {(Ra6a5+ Kc5c6 Ne3f5 Rh1f1+ Kf4e4 Rf1e1+ Ke4d4 Re1d1+
Kd4c3 Rd1a1 Nf5d4+ Kc6b6 Ra5b5+ Kb6c7 Kc3b4 Kc7d6 Rb5d5+ Kd6e7) +8.72/10 3}
Kc6 {(Kc5c6 Ne3f5) -7.79/9 2} 65. a4 {(a3a4 Rh1a1) +8.92/9 3} Ra1 {(Rh1a1
Kf4e4 Kc6b6 Ra5b5+ Kb6a6 Rb5b4 Ka6a5 c2c3 Ra1xa4 c4c5 Ra4a1 Ne3c4+ Ka5a6)
-7.87/9 2} 66. Ke4 {(Kf4e4 Ra1a3 Ne3d5 Ra3g3 Nd5b4+ Kc6c7 Ra5f5 Rg3g4+
Ke4d5 Kc7b6 Nb4d3 Kb6c7) +9.09/10 2} Ra3 {(Ra1a3 Ne3d5 Ra3h3 Ra5b5 Rh3h4+
Ke4d3 Rh4h3+ Kd3d4 Rh3h4+ Kd4c3 Rh4h3+ Kc3b4 Kc6d6 Rb5b6+ Kd6e5) -8.28/9 1}
67. Nd5 {(Ne3d5 Ra3h3 Nd5b4+ Kc6b7 Ra5b5+ Kb7c7 Nb4d5+ Kc7c6 a4a5 Rh3h4+
Ke4d3 Rh4h3+ Kd3d4 Rh3h4+ Kd4c3 Rh4h3+ Kc3d2) +9.17/9 2} Rg3 {(Ra3g3 Ra5b5)
-8.56/9 2} 68. Nb4+ {(Nd5b4+ Kc6d7 Ra5f5 Kd7e6 a4a5 Rg3c3 Rf5f6+ Ke6d7
Ke4d4) +9.49/8 1} Kc7 {(Kc6c7 Ra5f5 Rg3g4+ Rf5f4 Rg4g7 Nb4d5+ Kc7c6 Ke4d4
Rg7g2 Rf4f6+ Kc6d7) -8.64/8 1} 69. Rf5 {(Ra5f5 Rg3g4+ Rf5f4 Rg4g7 c4c5
Kc7b7 a4a5 Rg7e7+ Ke4d4 Re7g7 Nb4d5 Rg7g5) +9.69/9 2} Rg4+ {(Rg3g4+ Rf5f4
Rg4g7 a4a5 Kc7b7 c4c5 Rg7h7 a5a6+ Kb7a7 c5c6 Rh7c7) -8.76/8 1} 70. Rf4
{(Rf5f4 Rg4g7) +10.10/9 3} Rg7 {(Rg4g7 a4a5 Kc7b7 c4c5 Rg7h7 Ke4d5 Rh7h5+
Kd5d4 Rh5h7 a5a6+ Kb7a7 c5c6) -9.13/8 2} 71. Nd5+ {(Nb4d5+ Kc7c6 Ke4d4
Rg7g2 a4a5 Kc6b7 Rf4f6 Rg2g4+ Kd4c3 Rg4g3+ Kc3b4 Rg3g2 Rf6b6+ Kb7a7)
+9.85/8 1} Kc6 {(Kc7c6 Ke4d4 Rg7g2 a4a5 Kc6b7 Rf4f6 Rg2d2+ Kd4c5 Rd2g2)
-9.21/8 2} 72. Kd4 {(Ke4d4 Rg7g2) +10.02/10 2} Rg1 {(Rg7g1 Rf4f6+ Kc6b7
a4a5 Rg1g4+ Kd4c5 Rg4g7 Rf6b6+ Kb7a7 Kc5b5 Rg7d7 Rb6f6 Rd7b7+ Kb5c5 Rb7g7
Kc5d4 Rg7g4+ Rf6f4 Rg4xf4+ Nd5xf4) -9.33/8 1} 73. Rf6+ {(Rf4f6+ Kc6b7)
+10.22/8 1} Kb7 {(Kc6b7 a4a5 Rg1g7 Rf6b6+ Kb7a7 c4c5 Rg7g4+ Kd4d3 Rg4g5
Kd3c4 Rg5g4+) -9.57/8 1} 74. Rf7+ {(Rf6f7+ Kb7b8 a4a5 Rg1a1 Nd5b4 Ra1d1+
Kd4c5 Rd1a1 a5a6 Ra1a5+ Kc5d4) +10.26/7 2} Ka6 {(Kb7a6 c4c5 Rg1g4+ Rf7f4
Rg4g5 c2c4 Ka6a5 c5c6 Rg5g8 c6c7 Rg8c8) -9.85/7 1 Black resigns} *

[Uri Blass]

The second position is no good example for possibly too high double/isolated pawn penalty. As long as the engine does not see that Bxf3 loses material and the game, she will play it regardless how high the double/isolated pawn penalty is. Apart from this SF 1.8 sees very fast that Bxf3 loses. This blunder can only be played under heavy time pressure.

I disagree

SF1.8 does not play Bxf3 at small depths except depth 5 and it suggests Rb2 at depth 1.

f3 is more advanced pawn then g4 so programs can certainly reject Bxf3 based on evaluation.

New game, Friend mode
8/8/8/3B1pk1/2K3p1/5nP1/4RP2/5r2 w - - 0 1

Analysis by Stockfish 1.8 JA:

1.Re2-b2
² (0.56) Depth: 1 00:00:00
1.Re2-b2 Rf1-c1+ 2.Kc4-d3 Rc1-d1+ 3.Kd3-c4
= (0.24) Depth: 2 00:00:00
1.Re2-a2 Rf1-c1+ 2.Kc4-b4
² (0.40) Depth: 2 00:00:00
1.Kc4-c5 Rf1-d1
² (0.44) Depth: 2 00:00:00
1.Kc4-c5 Rf1-d1 2.Bd5-c4
² (0.44) Depth: 3 00:00:00
1.Kc4-c5 Rf1-c1+ 2.Bd5-c4 f5-f4 3.g3xf4+ Kg5xf4
² (0.28) Depth: 4 00:00:00
1.Re2-c2 Rf1-d1 2.Bd5xf3 g4xf3
² (0.32) Depth: 4 00:00:00
1.Re2-c2 f5-f4 2.Kc4-c5 Rf1-d1 3.Bd5xf3 g4xf3
² (0.40) Depth: 5 00:00:00
1.Bd5xf3 Rf1-c1+ 2.Kc4-d3 g4xf3 3.Re2-e5 Rc1-d1+ 4.Kd3-c4
² (0.68) Depth: 5 00:00:00
1.Bd5xf3 g4xf3
= (0.24) Depth: 6 00:00:00 6kN
1.Re2-c2 f5-f4 2.Kc4-c5 Rf1-d1 3.Rc2-c4 f4xg3 4.f2xg3
² (0.48) Depth: 6 00:00:01 7kN
1.Re2-c2 f5-f4 2.g3xf4+ Kg5xf4 3.Kc4-c5 Nf3-e5 4.Kc5-d6 Rf1-d1
² (0.40) Depth: 7 00:00:01 10kN
1.Re2-c2 f5-f4 2.g3xf4+ Kg5xf4 3.Kc4-c5 Nf3-e1 4.Rc2-d2 Ne1-d3+ 5.Rd2xd3 Rf1xf2 6.Rd3-d4+ Kf4-g5
² (0.48) Depth: 8 00:00:01 21kN
1.Re2-c2 f5-f4 2.g3xf4+ Kg5xf4 3.Kc4-c5 Nf3-e1 4.Rc2-d2 Ne1-d3+ 5.Rd2xd3 Rf1xf2 6.Rd3-d4+ Kf4-g5
² (0.48) Depth: 9 00:00:01 24kN
1.Re2-c2 f5-f4
² (0.40) Depth: 10 00:00:01 35kN
1.Re2-c2 f5-f4 2.g3xf4+ Kg5xf4 3.Kc4-c5 Rf1-a1 4.Rc2-c4+ Kf4-f5 5.Rc4-b4 Ra1-c1+ 6.Kc5-d6 Rc1-d1 7.Rb4-e4
² (0.40) Depth: 10 00:00:01 43kN
1.Re2-c2 f5-f4
² (0.32) Depth: 11 00:00:01 54kN
1.Re2-c2 f5-f4
= (0.24) Depth: 11 00:00:01 104kN
1.Kc4-c5 Rf1-c1+ 2.Kc5-d6 Rc1-d1 3.Re2-b2 Kg5-f6 4.Rb2-a2 Rd1-d2 5.Ra2xd2 Nf3xd2 6.Bd5-c6 Nd2-c4+ 7.Kd6-d5 Nc4-e5
² (0.32) Depth: 11 00:00:01 109kN
1.Kc4-c5 Rf1-c1+ 2.Kc5-d6 Rc1-d1 3.Re2-b2 Kg5-f6 4.Rb2-a2 Rd1-d2 5.Ra2xd2 Nf3xd2 6.Bd5-c6 Nd2-e4+ 7.Bc6xe4 f5xe4 8.Kd6-d5 Kf6-f5
² (0.32) Depth: 12 00:00:01 127kN
1.Kc4-c5 Rf1-c1+
= (0.24) Depth: 13 00:00:01 154kN
1.Kc4-c5 Rf1-c1+
= (0.16) Depth: 13 00:00:02 234kN
1.Kc4-c5 Rf1-c1+ 2.Kc5-b4 Rc1-d1 3.Bd5xf3 g4xf3 4.Re2-c2 Rd1-d7 5.Kb4-a4 Rd7-e7 6.Rc2-c3 Re7-e2 7.Rc3xf3 Re2-d2
= (0.12) Depth: 13 00:00:02 425kN
1.Kc4-c5 Rf1-c1+ 2.Kc5-b4 Rc1-d1 3.Kb4-c5 Rd1-c1+
= (0.00) Depth: 14 00:00:02 682kN
1.Kc4-c5 Rf1-c1+ 2.Kc5-b4 Rc1-d1 3.Kb4-c5 Rd1-c1+
= (0.00) Depth: 15 00:00:03 1320kN
1.Kc4-c5 Rf1-c1+ 2.Kc5-b4 Rc1-d1 3.Kb4-c5 Rd1-c1+
= (0.00) Depth: 16 00:00:05 1499kN

(, 09.07.2010)

[lech]

I think that my proposition (mobility and safety) can be good for this issue, but of course, in the mix with the original variables: doubled, isolated ........
It is not easy to do it correctly.