Opening books

[Gábor Szõts]

Geschrieben von: / Posted by: Gábor Szõts at 05 June 2000 10:49:05:
Watching the game LG2000 2.7 - Crafty 17.10 (see below) from my GS-6 tournament (to be appearing - hopefully - soon on Frank's page) I recognized I have doubts about the benefits of an opening book.
[Event "Computer chess game"]
[Site "A MI GÉPÜNK"]
[Date "2000.06.02"]
[Round "-"]
[White "LG2000v27"]
[Black "Crafty-17_10c"]
[Result "1-0"]
[TimeControl "1800"]
1. Nf3 Nf6 2. c4 g6 3. d4 Bg7 4. Nc3 O-O 5. e4 d6 6. Be2 e5 7. O-O Nc6 8.
d5 Ne7 9. Nd2 a5 10. a3 Nd7 11. Rb1 f5 12. b4 Kh8 13. Qc2 Ng8 14. f3 Ngf6
15. Bd3 f4 16. Nb5 b6 17. c5 dxc5 18. bxa5 Rxa5 19. Nc4 Ra8 20. a4 Ne8 21.
a5 Ba6 22. Bd2 Kg8 23. d6 cxd6 24. axb6 h6 25. Ba5 Qe7 26. Rfd1 Nb8 27. Nc7
Nxc7 28. bxc7 Nc6 29. Nb6 Qxc7 30. Nxa8 Qxa5 31. Ra1 Qd8 32. Qa2+ Kh8 33.
Qxa6 Nd4 34. Qb7 Qc8 35. Qxc8 Rxc8 36. Nb6 Rd8 37. Nd5 Kh7 38. Ra7 g5 39.
Bc4 Kg6 40. Ne7+ Kf6 41. Bf7 g4 42. Nd5+ Kg5 43. Bh5 Bf8 44. fxg4 Rb8 45.
Rf7 Kh4 46. Nf6 Rb2 47. g5 Be7 48. Rxe7 Kxg5 49. Rf7 Rb3 50. Rf8 Ne6 51.
h4+ Kxh4 52. Rg8 Ng5 53. Kf2 Rb2+ 54. Be2 Rxe2+ 55. Kxe2 Kg3 56. Rh1 f3+
57. gxf3
{Black resigns} 1-0
Look: in a long variant of the King's Indian Defence they reached a position in which humans know that white has to attack on the queenside while black on the kingside. But Crafty apparently doesn't know this! He did nothing, just waited to be destroyed in what was a completely onesided game. The position was simply not in accordance with his style.
That means, in my opinion, that we have to be careful creating opening books for an engine. It is not enough that the source games be of high quality. The book should also be suitable for the style and abilities of the engine. And too long lines should also be avoided: let the program choose the line which will suit him best, lest it be too late to recover from a line it wouldn't want to play left to his own devices.
To be more concrete, for Crafty I would choose games from Karpov's repertoire, for AnMon I would choose games from Shirov, for example. For LG and Comet, I would choose Anand or Kasparov. I'm not a big chess player, so other choices may easily be better.

With best wishes,
Gábor

[Dann Corbit]

Geschrieben von: / Posted by: Dann Corbit at 05 June 2000 21:02:25:
Als Antwort auf: / As an answer to: Opening books geschrieben von: / posted by: Gábor Szõts at 05 June 2000 10:49:05:

Watching the game LG2000 2.7 - Crafty 17.10 (see below) from my GS-6 tournament (to be appearing - hopefully - soon on Frank's page) I recognized I have doubts about the benefits of an opening book.
[Event "Computer chess game"]
[Site "A MI GÉPÜNK"]
[Date "2000.06.02"]
[Round "-"]
[White "LG2000v27"]
[Black "Crafty-17_10c"]
[Result "1-0"]
[TimeControl "1800"]
1. Nf3 Nf6 2. c4 g6 3. d4 Bg7 4. Nc3 O-O 5. e4 d6 6. Be2 e5 7. O-O Nc6 8.
d5 Ne7 9. Nd2 a5 10. a3 Nd7 11. Rb1 f5 12. b4 Kh8 13. Qc2 Ng8 14. f3 Ngf6
15. Bd3 f4 16. Nb5 b6 17. c5 dxc5 18. bxa5 Rxa5 19. Nc4 Ra8 20. a4 Ne8 21.
a5 Ba6 22. Bd2 Kg8 23. d6 cxd6 24. axb6 h6 25. Ba5 Qe7 26. Rfd1 Nb8 27. Nc7
Nxc7 28. bxc7 Nc6 29. Nb6 Qxc7 30. Nxa8 Qxa5 31. Ra1 Qd8 32. Qa2+ Kh8 33.
Qxa6 Nd4 34. Qb7 Qc8 35. Qxc8 Rxc8 36. Nb6 Rd8 37. Nd5 Kh7 38. Ra7 g5 39.
Bc4 Kg6 40. Ne7+ Kf6 41. Bf7 g4 42. Nd5+ Kg5 43. Bh5 Bf8 44. fxg4 Rb8 45.
Rf7 Kh4 46. Nf6 Rb2 47. g5 Be7 48. Rxe7 Kxg5 49. Rf7 Rb3 50. Rf8 Ne6 51.
h4+ Kxh4 52. Rg8 Ng5 53. Kf2 Rb2+ 54. Be2 Rxe2+ 55. Kxe2 Kg3 56. Rh1 f3+
57. gxf3
{Black resigns} 1-0
Look: in a long variant of the King's Indian Defence they reached a position in which humans know that white has to attack on the queenside while black on the kingside. But Crafty apparently doesn't know this! He did nothing, just waited to be destroyed in what was a completely onesided game. The position was simply not in accordance with his style.
That means, in my opinion, that we have to be careful creating opening books for an engine. It is not enough that the source games be of high quality. The book should also be suitable for the style and abilities of the engine. And too long lines should also be avoided: let the program choose the line which will suit him best, lest it be too late to recover from a line it wouldn't want to play left to his own devices.
To be more concrete, for Crafty I would choose games from Karpov's repertoire, for AnMon I would choose games from Shirov, for example. For LG and Comet, I would choose Anand or Kasparov. I'm not a big chess player, so other choices may easily be better.

With best wishes,
Gábor

That is why I am in favor of analyzing all the ending positions for the opening books. If a book has 10 million positions, it is too many to analyze carefully. But the the very last position from each line where you fall out of the book can be analyzed at very long time control.
I think that there are several kinds of book errors.
1. Outright bugs -- huge tactical blunders missed by all who played them
2. Positional moves with benefit too far -- computers don't know the *game plan!*
3. Moves that do not match the style of the engine but which would be sound with another computer. These would probably be the hardest to remove.
4. Sacrifices or gambits that the computers don't "grok" the game plan. Sound for a GM player but not for most computers.
Probably others as well. Most of these can [eventually] be solved by deep analysis and a learn file.


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