Skippers sixty memorable bugs: bug 8

[Henk]

In this position Skipper plays Nf2.

[d] r1bqkb1r/ppp1pppp/2np4/4P3/3P2n1/5N1P/PPP2PP1/RNBQKB1R b KQkq - 0 1

[pgn]
1. e4 Nc6
2. Nf3 Nf6
3. e5 Ng4
4. d4 d6
5. h3 Nf2
[/pgn]

Code: Select all

Depth  Value   Time
  1  -3500.00   0.002          86   g4h6 
  2  -4048.00   0.004         136   g4f2 
  3  -2148.00   0.009         421   g4f2 
  4  -2648.00   0.022        1685   g4f2 
  5  -1198.00   0.050        4042   g4f2 
  6  -2348.00   0.115       10215   g4f2 e1f2 d6e5 d4d5 c8e6 b1c3 
  7  -1646.00   0.328       27122   g4f2 e1f2 d6e5 d4d5 e5e4 f2e1 e7e5 
  8  -1648.00   0.890       78992   g4f2 e1f2 d6e5 d4d5 e7e6 b1c3 e6d5 c3d5 
  9  -2746.00   2.564      224170   g4f2 e1f2 d6e5 f1b5 e5e4 f3e5 c8d7 e5d7 d8d7 

Strange when I load the position and try to reproduce it I get the normal:

Code: Select all

Depth  Value   Time
  1  -1000.00   0.002         106   g4h6 
  2  -2000.00   0.005         282   g4h6 b1c3 
  3  -2252.00   0.013        1201   g4h6 c1h6 g7h6 
  4  -3252.00   0.029        2952   g4h6 c1h6 g7h6 b1c3 
  5  -2452.00   0.057        6140   g4h6 c1h6 g7h6 b1c3 d6e5 
  6  -3052.00   0.114       12947   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 
  7  -2552.00   0.293       31367   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 c8d7 
  8  -3052.00   0.761       84134   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 c8d7 f1e2 
  9  -2352.00   2.418      261383   g4h6 c1h6 g7h6 b1c3 c8d7 e5d6 c7d6 d4d5 c6b4 
 10  -2852.00   5.719      667175   g4h6 c1h6 g7h6 e5d6 c7d6 d4d5 c6e5 b1c3 f8g7 

But that is not what it plays in a normal game. For I encounter this position very often. Difference in evaluation is not much so maybe I should reduce the penalty for losing castling rights a bit.

[zullil]

In this position Skipper plays Nf2.

[d] r1bqkb1r/ppp1pppp/2np4/4P3/3P2n1/5N1P/PPP2PP1/RNBQKB1R b KQkq - 0 1


Strange when I load the position and try to reproduce it I get the normal:

Code: Select all

Depth  Value   Time
  1  -1000.00   0.002         106   g4h6 
  2  -2000.00   0.005         282   g4h6 b1c3 
  3  -2252.00   0.013        1201   g4h6 c1h6 g7h6 
  4  -3252.00   0.029        2952   g4h6 c1h6 g7h6 b1c3 
  5  -2452.00   0.057        6140   g4h6 c1h6 g7h6 b1c3 d6e5 
  6  -3052.00   0.114       12947   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 
  7  -2552.00   0.293       31367   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 c8d7 
  8  -3052.00   0.761       84134   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 c8d7 f1e2 
  9  -2352.00   2.418      261383   g4h6 c1h6 g7h6 b1c3 c8d7 e5d6 c7d6 d4d5 c6b4 
 10  -2852.00   5.719      667175   g4h6 c1h6 g7h6 e5d6 c7d6 d4d5 c6e5 b1c3 f8g7 

But that is not what it plays in a normal game.

Move in game differs from move in search of position suggests a hash table issue?

[Henk]

Pfft I lowered the castling rights penalty. Now it plays Nd5. At last ...

[I played with white. Time control five minutes]

[pgn]
1. e4 Nc6
2. Nf3 Nf6
3. e5 Nd5
4. c4 Nb6
5. d4 e6
6. a4 Bb4
7. Nc3 0-0
8. Bd3 d5
9. Bh7 Kh7
10. Ng5 Kg8
11. Qh5 Re8
12. Qf7 Kh8
13. Qh5 Kg8
14. Qh7 Kf8
15. Qh8 Ke7
16. Qg7 Bc3
[/pgn]

[Henk]

In this position Skipper plays Nf2.

[d] r1bqkb1r/ppp1pppp/2np4/4P3/3P2n1/5N1P/PPP2PP1/RNBQKB1R b KQkq - 0 1


Strange when I load the position and try to reproduce it I get the normal:

Code: Select all

Depth  Value   Time
  1  -1000.00   0.002         106   g4h6 
  2  -2000.00   0.005         282   g4h6 b1c3 
  3  -2252.00   0.013        1201   g4h6 c1h6 g7h6 
  4  -3252.00   0.029        2952   g4h6 c1h6 g7h6 b1c3 
  5  -2452.00   0.057        6140   g4h6 c1h6 g7h6 b1c3 d6e5 
  6  -3052.00   0.114       12947   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 
  7  -2552.00   0.293       31367   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 c8d7 
  8  -3052.00   0.761       84134   g4h6 c1h6 g7h6 b1c3 d6e5 d4e5 c8d7 f1e2 
  9  -2352.00   2.418      261383   g4h6 c1h6 g7h6 b1c3 c8d7 e5d6 c7d6 d4d5 c6b4 
 10  -2852.00   5.719      667175   g4h6 c1h6 g7h6 e5d6 c7d6 d4d5 c6e5 b1c3 f8g7 

But that is not what it plays in a normal game.

Move in game differs from move in search of position suggests a hash table issue?

At this moment it clears hash before searching when there are more than 400000 entries in it. I have not implemented an ageing mechanism.

[Evert]

In this position Skipper plays Nf2.

[d] r1bqkb1r/ppp1pppp/2np4/4P3/3P2n1/5N1P/PPP2PP1/RNBQKB1R b KQkq - 0 1

[...]
Strange when I load the position and try to reproduce it I get the normal:

Code: Select all

Depth  Value   Time
  1  -1000.00   0.002         106   g4h6 

[...]

In what parallel world is -1000 a normal value for that position?

[Henk]

In a virtual world anything is possible. What's wrong with -1000. -1000 means -100 cps.

[Evert]

In a virtual world anything is possible. What's wrong with -1000. -1000 means -100 cps.

[d]r1bqkb1r/ppp1pppp/2np3n/4P3/3P4/5N1P/PPP2PP1/RNBQKB1R w KQkq - 1 2

You mean what's wrong with evaluating the above position as a pawn down for black? Other than black not being a pawn down?

[Henk]

In a virtual world anything is possible. What's wrong with -1000. -1000 means -100 cps.

[d]r1bqkb1r/ppp1pppp/2np3n/4P3/3P4/5N1P/PPP2PP1/RNBQKB1R w KQkq - 1 2

You mean what's wrong with evaluating the above position as a pawn down for black? Other than black not being a pawn down?

Sorry mistake. I'm not used to thinking in centi pawns. It means 0.1 pawns = 10 cps

[Henk]

[d] r1bq1rk1/ppp2pp1/1nn1p3/3pP1N1/PbPP4/2N5/1P3PPP/R1BQK2R w KQ - 0 1

It needs three minutes to see that Qg5 is best in this position after Qh5. So it needs three minutes to see that Qh5 is winning. No wonder that it will never see the standard sacrifice Bh7

Code: Select all

Depth  Value   Time
  1  -27752.00   0.023         486   c4d5 
  2  -28552.00   0.030        1124   c4d5 e6d5 
  3  -28052.00   0.055        3322   c4d5 e6d5 c1e3 
  4  -28252.00   0.125       10711   c4c5 b6c4 f2f4 c8d7 
  5  -28252.00   0.242       23916   c4c5 b6c4 f2f4 c8d7 d1b3 
  6  -28652.00   0.687       81285   c4c5 b6c4 f2f4 c8d7 d1b3 a7a5 
  7  -28452.00   1.299      159131   c4c5 b6c4 f2f4 c8d7 d1d3 a7a5 b2b3 
  8  -11136.00   10.523     1202131   d1h5 f8e8 h5f7 g8h8 f7h5 h8g8 h5f7 
  9  -11136.00   12.903     1461618   d1h5 f8e8 h5f7 g8h8 f7h5 h8g8 h5f7 
 10  -11136.00   19.435     2177774   d1h5 f8e8 h5f7 g8h8 f7h5 h8g8 h5f7 
 11  -3920.00   39.786     4537072   d1h5 f8e8 h5f7 g8h8 f7h5 h8g8 h5h7 g8f8 h7h8 
 12  19004.00   178.488    20052362   d1h5 d8g5 c1g5 b6c4 0-0-0 b4c3 b2c3 c4b6 h5f3 

[Henk]

In this position Skipper plays Bd2 and thinks his position is worse -0.32. What do normal engines play here ? How smart is your engine ?


[d] r1bq1rk1/pppn1ppp/2n1p3/2PpP3/Pb1P4/2NB1N2/1P3PPP/R1BQK2R w KQ - 1 2

Code: Select all

Depth  Value   Time
  1  -4100.00   0.018         394   c1d2 
  2  -4500.00   0.028        1917   c1d2 a7a5 
  3  -4100.00   0.042        3624   c1d2 h7h5 h2h4 
  4  -4300.00   0.108       15478   h2h4 h7h6 c1d2 a7a5 
  5  -4100.00   0.257       39956   h2h4 h7h6 c1d2 a7a5 b2b3 
  6  -4100.00   0.563      101565   h2h4 h7h6 c1d2 a7a5 h4h5 d8e7 
  7  -4100.00   2.068      404468   h2h4 h7h6 c1d2 a7a6 b2b3 h6h5 d1e2 
  8  -3900.00   9.292     1816195   h2h4 h7h6 h4h5 d8e7 c1d2 a7a5 b2b3 g8h8 
  9  -3200.00   40.067     7705559   c1d2 h7h5 c3a2 a7a5 d2c3 d8e7 d3b5 b4c3 b2c3