Page 4 of 8

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 9:56 am
by zullil
zullil wrote:
Wed May 15, 2019 8:40 pm
jp wrote:
Wed May 15, 2019 8:15 pm

e.g.
zullil wrote:
Wed May 15, 2019 10:28 am
Stockfish-dev prefers Bf5 to Bh3:
-1.58 14. Bf5 Rf8 (depth 56, 8:04:21)
-1.83 14. Bh3 Bxe5 (depth 56, 8:04:21)
The difference in eval. here is pretty small too, even though it's gone to depth 56.
Depth 60 now. I agree with Dann; this gambit is a loser for White.

-1.83 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qb4 38. a3 Qb1+ 39. Kf2 Qc1 40. Rd1 Qc2+ 41. R3d2 Qc4 42. Kg3 Kb8 43. Rd5 a5 44. R1d2 a4 45. Kh2 Qc1 46. Rd6 Qxa3 47. Rb6+ Rb7 48. Rdd6 Rxb6 49. Rxb6+ Kc7 50. Rxg6 (depth 60, 22:16:07)

-2.03 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. Kh1 Ka7 26. Rf2 Qb5 27. Re3 Rh5 28. Nc3 Qe8 29. Nd5 Rc6 30. b3 Qd7 31. Rf1 Rh8 32. Rf7 Ka6 33. Rf2 Re8 34. Bd6 Nd4 35. a4 Nf5 36. Bh3 g6 37. Bxf5 gxf5 38. Nf6 Qd8 39. Nxe8 Qxe8 40. Rff3 Qe6 41. h5 Rb6 42. Bxc5 Rxb3 43. Kg1 Qg8+ 44. Kf2 Qd5 45. e6 Rb2+ 46. Kf1 Qxc5 47. e7 Rb1+ 48. Kg2 Qc2+ 49. Kg3 (depth 60, 22:16:07)
One more iteration. Now Bh3 is preferred:

-1.74 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. b3 Rh5 26. Kh1 Ka7 27. Rf2 Rc6 28. a4 Rc8 29. Re4 Rh6 30. Bh3 Qc6 31. Nc3 Rch8 32. Rf7 g5 33. Nb5+ Kb6 34. Bxg5 Nxg5 35. hxg5 Rxh3 36. Rf6 Rxh2+ 37. Kg1 R2h3 38. Rxc6+ Kxc6 39. Rg4 Rxd3 40. g6 Kd5 41. g7 Rg8 42. Rg5 Rxb3 43. Nc7+ Kc6 44. Nb5 Rb4 45. Nd6 Rf4 46. Nf5 Rxf5 47. Rxf5 Rxg7+ 48. Kf2 Kd5 49. e6+ Kd6 50. Ke1 b6 51. Rf6 Ke7 52. Rf3 c4 53. Kd2 Kxe6 (depth 61, 10:21:06)

-1.90 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qc1+ 38. Rd1 Qc2 39. R1d2 Qc4 40. Kf2 Rf7 41. Kg1 Qe4 42. Kh2 Re7 43. Rc3 Rxe5 44. Rdc2 Rf5 45. Rxc5+ Rxc5 46. Rxc5+ Kb7 47. Rb5+ Ka6 48. Rg5 Qb1 49. Rd5 Qxa2 50. Rd7 Qb2 51. Rd6+ Ka5 (depth 61, 10:21:06)

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 9:59 am
by chrisw
Nordlandia wrote:
Thu May 16, 2019 9:38 am
jp wrote:
Thu May 16, 2019 8:53 am
Nordlandia wrote:
Thu May 16, 2019 7:50 am
There is a very similar line. This line is more sound for white.
Why do you think it's more sound? The different Black pawn placement doesn't make SF (at low depth) like it any more than the first line.
Well, K13.01 held against latest brainfish. I remember that in the original line, K almost always lost.

exactly, avoid exchanges, avoid pressing too much, get the minor pieces and pawns in positions where they are mutually defending each other and hold the centre.

the AB programs were all overpressing, sit back and keep things tight.

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 10:16 am
by chrisw
zullil wrote:
Thu May 16, 2019 9:56 am
zullil wrote:
Wed May 15, 2019 8:40 pm
jp wrote:
Wed May 15, 2019 8:15 pm

e.g.
zullil wrote:
Wed May 15, 2019 10:28 am
Stockfish-dev prefers Bf5 to Bh3:
-1.58 14. Bf5 Rf8 (depth 56, 8:04:21)
-1.83 14. Bh3 Bxe5 (depth 56, 8:04:21)
The difference in eval. here is pretty small too, even though it's gone to depth 56.
Depth 60 now. I agree with Dann; this gambit is a loser for White.

-1.83 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qb4 38. a3 Qb1+ 39. Kf2 Qc1 40. Rd1 Qc2+ 41. R3d2 Qc4 42. Kg3 Kb8 43. Rd5 a5 44. R1d2 a4 45. Kh2 Qc1 46. Rd6 Qxa3 47. Rb6+ Rb7 48. Rdd6 Rxb6 49. Rxb6+ Kc7 50. Rxg6 (depth 60, 22:16:07)

-2.03 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. Kh1 Ka7 26. Rf2 Qb5 27. Re3 Rh5 28. Nc3 Qe8 29. Nd5 Rc6 30. b3 Qd7 31. Rf1 Rh8 32. Rf7 Ka6 33. Rf2 Re8 34. Bd6 Nd4 35. a4 Nf5 36. Bh3 g6 37. Bxf5 gxf5 38. Nf6 Qd8 39. Nxe8 Qxe8 40. Rff3 Qe6 41. h5 Rb6 42. Bxc5 Rxb3 43. Kg1 Qg8+ 44. Kf2 Qd5 45. e6 Rb2+ 46. Kf1 Qxc5 47. e7 Rb1+ 48. Kg2 Qc2+ 49. Kg3 (depth 60, 22:16:07)
One more iteration. Now Bh3 is preferred:

-1.74 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. b3 Rh5 26. Kh1 Ka7 27. Rf2 Rc6 28. a4 Rc8 29. Re4 Rh6 30. Bh3 Qc6 31. Nc3 Rch8 32. Rf7 g5 33. Nb5+ Kb6 34. Bxg5 Nxg5 35. hxg5 Rxh3 36. Rf6 Rxh2+ 37. Kg1 R2h3 38. Rxc6+ Kxc6 39. Rg4 Rxd3 40. g6 Kd5 41. g7 Rg8 42. Rg5 Rxb3 43. Nc7+ Kc6 44. Nb5 Rb4 45. Nd6 Rf4 46. Nf5 Rxf5 47. Rxf5 Rxg7+ 48. Kf2 Kd5 49. e6+ Kd6 50. Ke1 b6 51. Rf6 Ke7 52. Rf3 c4 53. Kd2 Kxe6 (depth 61, 10:21:06)

-1.90 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qc1+ 38. Rd1 Qc2 39. R1d2 Qc4 40. Kf2 Rf7 41. Kg1 Qe4 42. Kh2 Re7 43. Rc3 Rxe5 44. Rdc2 Rf5 45. Rxc5+ Rxc5 46. Rxc5+ Kb7 47. Rb5+ Ka6 48. Rg5 Qb1 49. Rd5 Qxa2 50. Rd7 Qb2 51. Rd6+ Ka5 (depth 61, 10:21:06)
the final position in the 14. Bh3 line is a draw. While SF says -1.74.

AB game rollouts to evaluate this gambit are not reliable.

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 10:27 am
by jp
chrisw wrote:
Thu May 16, 2019 10:16 am
zullil wrote:
Thu May 16, 2019 9:56 am
One more iteration. Now Bh3 is preferred:
-1.74 14. Bh3 Bxe5 ... 53. Kd2 Kxe6 (depth 61, 10:21:06)
the final position in the 14. Bh3 line is a draw. While SF says -1.74.
AB game rollouts to evaluate this gambit are not reliable.
I haven't seen it yet, but the very end of the line won't be reliable. It's way beyond 61 plies. What about at move 45 or 35?

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 10:35 am
by zullil
chrisw wrote:
Thu May 16, 2019 10:16 am
zullil wrote:
Thu May 16, 2019 9:56 am
zullil wrote:
Wed May 15, 2019 8:40 pm
jp wrote:
Wed May 15, 2019 8:15 pm

e.g.
zullil wrote:
Wed May 15, 2019 10:28 am
Stockfish-dev prefers Bf5 to Bh3:
-1.58 14. Bf5 Rf8 (depth 56, 8:04:21)
-1.83 14. Bh3 Bxe5 (depth 56, 8:04:21)
The difference in eval. here is pretty small too, even though it's gone to depth 56.
Depth 60 now. I agree with Dann; this gambit is a loser for White.

-1.83 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qb4 38. a3 Qb1+ 39. Kf2 Qc1 40. Rd1 Qc2+ 41. R3d2 Qc4 42. Kg3 Kb8 43. Rd5 a5 44. R1d2 a4 45. Kh2 Qc1 46. Rd6 Qxa3 47. Rb6+ Rb7 48. Rdd6 Rxb6 49. Rxb6+ Kc7 50. Rxg6 (depth 60, 22:16:07)

-2.03 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. Kh1 Ka7 26. Rf2 Qb5 27. Re3 Rh5 28. Nc3 Qe8 29. Nd5 Rc6 30. b3 Qd7 31. Rf1 Rh8 32. Rf7 Ka6 33. Rf2 Re8 34. Bd6 Nd4 35. a4 Nf5 36. Bh3 g6 37. Bxf5 gxf5 38. Nf6 Qd8 39. Nxe8 Qxe8 40. Rff3 Qe6 41. h5 Rb6 42. Bxc5 Rxb3 43. Kg1 Qg8+ 44. Kf2 Qd5 45. e6 Rb2+ 46. Kf1 Qxc5 47. e7 Rb1+ 48. Kg2 Qc2+ 49. Kg3 (depth 60, 22:16:07)
One more iteration. Now Bh3 is preferred:

-1.74 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. b3 Rh5 26. Kh1 Ka7 27. Rf2 Rc6 28. a4 Rc8 29. Re4 Rh6 30. Bh3 Qc6 31. Nc3 Rch8 32. Rf7 g5 33. Nb5+ Kb6 34. Bxg5 Nxg5 35. hxg5 Rxh3 36. Rf6 Rxh2+ 37. Kg1 R2h3 38. Rxc6+ Kxc6 39. Rg4 Rxd3 40. g6 Kd5 41. g7 Rg8 42. Rg5 Rxb3 43. Nc7+ Kc6 44. Nb5 Rb4 45. Nd6 Rf4 46. Nf5 Rxf5 47. Rxf5 Rxg7+ 48. Kf2 Kd5 49. e6+ Kd6 50. Ke1 b6 51. Rf6 Ke7 52. Rf3 c4 53. Kd2 Kxe6 (depth 61, 10:21:06)

-1.90 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qc1+ 38. Rd1 Qc2 39. R1d2 Qc4 40. Kf2 Rf7 41. Kg1 Qe4 42. Kh2 Re7 43. Rc3 Rxe5 44. Rdc2 Rf5 45. Rxc5+ Rxc5 46. Rxc5+ Kb7 47. Rb5+ Ka6 48. Rg5 Qb1 49. Rd5 Qxa2 50. Rd7 Qb2 51. Rd6+ Ka5 (depth 61, 10:21:06)
the final position in the 14. Bh3 line is a draw. While SF says -1.74.

AB game rollouts to evaluate this gambit are not reliable.
Indeed, the final position in the 14. Bh3 line is a draw. But what about the position after 47. Rxf5 ?



So, as ever, deep A/B searches from the root are not definitive. Nonetheless, it's hard to imagine that this gambit gives White any winning chances. Unless Black is a human.

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 10:45 am
by AdminX
zullil wrote:
Thu May 16, 2019 10:35 am

Indeed, the final position in the 14. Bh3 line is a draw. But what about the position after 47. Rxf5 ?



So, as ever, deep A/B searches from the root are not definitive. Nonetheless, it's hard to imagine that this gambit gives White any winning chances. Unless Black is a human.
I agree, "it's hard to imagine that this gambit gives White any winning chances" at least for engine vs engine games. I would however play it if presented the opportunity in human vs human games from time to time. Maybe not in Blitz, but at a nice LTC I would.

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 10:59 am
by chrisw
zullil wrote:
Thu May 16, 2019 10:35 am
chrisw wrote:
Thu May 16, 2019 10:16 am
zullil wrote:
Thu May 16, 2019 9:56 am
zullil wrote:
Wed May 15, 2019 8:40 pm
jp wrote:
Wed May 15, 2019 8:15 pm

e.g.
zullil wrote:
Wed May 15, 2019 10:28 am
Stockfish-dev prefers Bf5 to Bh3:
-1.58 14. Bf5 Rf8 (depth 56, 8:04:21)
-1.83 14. Bh3 Bxe5 (depth 56, 8:04:21)
The difference in eval. here is pretty small too, even though it's gone to depth 56.
Depth 60 now. I agree with Dann; this gambit is a loser for White.

-1.83 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qb4 38. a3 Qb1+ 39. Kf2 Qc1 40. Rd1 Qc2+ 41. R3d2 Qc4 42. Kg3 Kb8 43. Rd5 a5 44. R1d2 a4 45. Kh2 Qc1 46. Rd6 Qxa3 47. Rb6+ Rb7 48. Rdd6 Rxb6 49. Rxb6+ Kc7 50. Rxg6 (depth 60, 22:16:07)

-2.03 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. Kh1 Ka7 26. Rf2 Qb5 27. Re3 Rh5 28. Nc3 Qe8 29. Nd5 Rc6 30. b3 Qd7 31. Rf1 Rh8 32. Rf7 Ka6 33. Rf2 Re8 34. Bd6 Nd4 35. a4 Nf5 36. Bh3 g6 37. Bxf5 gxf5 38. Nf6 Qd8 39. Nxe8 Qxe8 40. Rff3 Qe6 41. h5 Rb6 42. Bxc5 Rxb3 43. Kg1 Qg8+ 44. Kf2 Qd5 45. e6 Rb2+ 46. Kf1 Qxc5 47. e7 Rb1+ 48. Kg2 Qc2+ 49. Kg3 (depth 60, 22:16:07)
One more iteration. Now Bh3 is preferred:

-1.74 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. b3 Rh5 26. Kh1 Ka7 27. Rf2 Rc6 28. a4 Rc8 29. Re4 Rh6 30. Bh3 Qc6 31. Nc3 Rch8 32. Rf7 g5 33. Nb5+ Kb6 34. Bxg5 Nxg5 35. hxg5 Rxh3 36. Rf6 Rxh2+ 37. Kg1 R2h3 38. Rxc6+ Kxc6 39. Rg4 Rxd3 40. g6 Kd5 41. g7 Rg8 42. Rg5 Rxb3 43. Nc7+ Kc6 44. Nb5 Rb4 45. Nd6 Rf4 46. Nf5 Rxf5 47. Rxf5 Rxg7+ 48. Kf2 Kd5 49. e6+ Kd6 50. Ke1 b6 51. Rf6 Ke7 52. Rf3 c4 53. Kd2 Kxe6 (depth 61, 10:21:06)

-1.90 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qc1+ 38. Rd1 Qc2 39. R1d2 Qc4 40. Kf2 Rf7 41. Kg1 Qe4 42. Kh2 Re7 43. Rc3 Rxe5 44. Rdc2 Rf5 45. Rxc5+ Rxc5 46. Rxc5+ Kb7 47. Rb5+ Ka6 48. Rg5 Qb1 49. Rd5 Qxa2 50. Rd7 Qb2 51. Rd6+ Ka5 (depth 61, 10:21:06)
the final position in the 14. Bh3 line is a draw. While SF says -1.74.

AB game rollouts to evaluate this gambit are not reliable.
Indeed, the final position in the 14. Bh3 line is a draw. But what about the position after 47. Rxf5 ?



So, as ever, deep A/B searches from the root are not definitive. Nonetheless, it's hard to imagine that this gambit gives White any winning chances. Unless Black is a human.
Ah! I thought I was trying to prove at least a draw for white, not a win.

I would go back further. After 32 ... b5 33. Nb5+ Kb6 now Rf6! not Bxg5

Rf6 Rxf6 exf6 Rxh4 Bxe6 Rxe4 Bd8+ Ka6 dxe4 Qxe4 Kg1 Qe1+ Kg2 Qe2+ Kg3 Qxd8 f7 and fortress which SF cannot see.

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 12:07 pm
by zullil
chrisw wrote:
Thu May 16, 2019 10:59 am
zullil wrote:
Thu May 16, 2019 10:35 am
chrisw wrote:
Thu May 16, 2019 10:16 am
zullil wrote:
Thu May 16, 2019 9:56 am
zullil wrote:
Wed May 15, 2019 8:40 pm
jp wrote:
Wed May 15, 2019 8:15 pm

e.g.
zullil wrote:
Wed May 15, 2019 10:28 am
Stockfish-dev prefers Bf5 to Bh3:
-1.58 14. Bf5 Rf8 (depth 56, 8:04:21)
-1.83 14. Bh3 Bxe5 (depth 56, 8:04:21)
The difference in eval. here is pretty small too, even though it's gone to depth 56.
Depth 60 now. I agree with Dann; this gambit is a loser for White.

-1.83 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qb4 38. a3 Qb1+ 39. Kf2 Qc1 40. Rd1 Qc2+ 41. R3d2 Qc4 42. Kg3 Kb8 43. Rd5 a5 44. R1d2 a4 45. Kh2 Qc1 46. Rd6 Qxa3 47. Rb6+ Rb7 48. Rdd6 Rxb6 49. Rxb6+ Kc7 50. Rxg6 (depth 60, 22:16:07)

-2.03 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. Kh1 Ka7 26. Rf2 Qb5 27. Re3 Rh5 28. Nc3 Qe8 29. Nd5 Rc6 30. b3 Qd7 31. Rf1 Rh8 32. Rf7 Ka6 33. Rf2 Re8 34. Bd6 Nd4 35. a4 Nf5 36. Bh3 g6 37. Bxf5 gxf5 38. Nf6 Qd8 39. Nxe8 Qxe8 40. Rff3 Qe6 41. h5 Rb6 42. Bxc5 Rxb3 43. Kg1 Qg8+ 44. Kf2 Qd5 45. e6 Rb2+ 46. Kf1 Qxc5 47. e7 Rb1+ 48. Kg2 Qc2+ 49. Kg3 (depth 60, 22:16:07)
One more iteration. Now Bh3 is preferred:

-1.74 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. b3 Rh5 26. Kh1 Ka7 27. Rf2 Rc6 28. a4 Rc8 29. Re4 Rh6 30. Bh3 Qc6 31. Nc3 Rch8 32. Rf7 g5 33. Nb5+ Kb6 34. Bxg5 Nxg5 35. hxg5 Rxh3 36. Rf6 Rxh2+ 37. Kg1 R2h3 38. Rxc6+ Kxc6 39. Rg4 Rxd3 40. g6 Kd5 41. g7 Rg8 42. Rg5 Rxb3 43. Nc7+ Kc6 44. Nb5 Rb4 45. Nd6 Rf4 46. Nf5 Rxf5 47. Rxf5 Rxg7+ 48. Kf2 Kd5 49. e6+ Kd6 50. Ke1 b6 51. Rf6 Ke7 52. Rf3 c4 53. Kd2 Kxe6 (depth 61, 10:21:06)

-1.90 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qc1+ 38. Rd1 Qc2 39. R1d2 Qc4 40. Kf2 Rf7 41. Kg1 Qe4 42. Kh2 Re7 43. Rc3 Rxe5 44. Rdc2 Rf5 45. Rxc5+ Rxc5 46. Rxc5+ Kb7 47. Rb5+ Ka6 48. Rg5 Qb1 49. Rd5 Qxa2 50. Rd7 Qb2 51. Rd6+ Ka5 (depth 61, 10:21:06)
the final position in the 14. Bh3 line is a draw. While SF says -1.74.

AB game rollouts to evaluate this gambit are not reliable.
Indeed, the final position in the 14. Bh3 line is a draw. But what about the position after 47. Rxf5 ?



So, as ever, deep A/B searches from the root are not definitive. Nonetheless, it's hard to imagine that this gambit gives White any winning chances. Unless Black is a human.
Ah! I thought I was trying to prove at least a draw for white, not a win.

I would go back further. After 32 ... b5 33. Nb5+ Kb6 now Rf6! not Bxg5

Rf6 Rxf6 exf6 Rxh4 Bxe6 Rxe4 Bd8+ Ka6 dxe4 Qxe4 Kg1 Qe1+ Kg2 Qe2+ Kg3 Qxd8 f7 and fortress which SF cannot see.
One thing that comes to mind is the vital importance of good static evaluations of near-tablebase positions. Now that engines search so deeply, they end up "making their plans" out of the opening based on very shallow searches of endgame positions at the leaves of a deep tree. This seems like an area where Stockfish, for example, could improve a lot.

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 1:16 pm
by chrisw
zullil wrote:
Thu May 16, 2019 12:07 pm
chrisw wrote:
Thu May 16, 2019 10:59 am
zullil wrote:
Thu May 16, 2019 10:35 am
chrisw wrote:
Thu May 16, 2019 10:16 am
zullil wrote:
Thu May 16, 2019 9:56 am
zullil wrote:
Wed May 15, 2019 8:40 pm
jp wrote:
Wed May 15, 2019 8:15 pm

e.g.
zullil wrote:
Wed May 15, 2019 10:28 am
Stockfish-dev prefers Bf5 to Bh3:
-1.58 14. Bf5 Rf8 (depth 56, 8:04:21)
-1.83 14. Bh3 Bxe5 (depth 56, 8:04:21)
The difference in eval. here is pretty small too, even though it's gone to depth 56.
Depth 60 now. I agree with Dann; this gambit is a loser for White.

-1.83 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qb4 38. a3 Qb1+ 39. Kf2 Qc1 40. Rd1 Qc2+ 41. R3d2 Qc4 42. Kg3 Kb8 43. Rd5 a5 44. R1d2 a4 45. Kh2 Qc1 46. Rd6 Qxa3 47. Rb6+ Rb7 48. Rdd6 Rxb6 49. Rxb6+ Kc7 50. Rxg6 (depth 60, 22:16:07)

-2.03 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. Kh1 Ka7 26. Rf2 Qb5 27. Re3 Rh5 28. Nc3 Qe8 29. Nd5 Rc6 30. b3 Qd7 31. Rf1 Rh8 32. Rf7 Ka6 33. Rf2 Re8 34. Bd6 Nd4 35. a4 Nf5 36. Bh3 g6 37. Bxf5 gxf5 38. Nf6 Qd8 39. Nxe8 Qxe8 40. Rff3 Qe6 41. h5 Rb6 42. Bxc5 Rxb3 43. Kg1 Qg8+ 44. Kf2 Qd5 45. e6 Rb2+ 46. Kf1 Qxc5 47. e7 Rb1+ 48. Kg2 Qc2+ 49. Kg3 (depth 60, 22:16:07)
One more iteration. Now Bh3 is preferred:

-1.74 14. Bh3 Bxe5 15. fxe5 Nc6 16. d3 Nd4 17. Bg5 exd3 18. cxd3 Kc6 19. g3 h4 20. gxh4 Ne6 21. Bg2+ Kc7 22. Nd5+ Kb8 23. Be7 a5 24. Rae1 Ra6 25. b3 Rh5 26. Kh1 Ka7 27. Rf2 Rc6 28. a4 Rc8 29. Re4 Rh6 30. Bh3 Qc6 31. Nc3 Rch8 32. Rf7 g5 33. Nb5+ Kb6 34. Bxg5 Nxg5 35. hxg5 Rxh3 36. Rf6 Rxh2+ 37. Kg1 R2h3 38. Rxc6+ Kxc6 39. Rg4 Rxd3 40. g6 Kd5 41. g7 Rg8 42. Rg5 Rxb3 43. Nc7+ Kc6 44. Nb5 Rb4 45. Nd6 Rf4 46. Nf5 Rxf5 47. Rxf5 Rxg7+ 48. Kf2 Kd5 49. e6+ Kd6 50. Ke1 b6 51. Rf6 Ke7 52. Rf3 c4 53. Kd2 Kxe6 (depth 61, 10:21:06)

-1.90 14. Bf5 Rf8 15. Bg6 Qe6 16. Nb5+ Kd8 17. Nxd6 Qxd6 18. d3 Qd4+ 19. Rf2 e3 20. Re2 Qxf4 21. Nf3 Qf6 22. Be4 Kc7 23. Bxe3 Nd7 24. Rb1 Rae8 25. b4 Qa6 26. c4 cxb4 27. Rxb4 b6 28. h3 Kc8 29. Rb5 Qa4 30. Bf2 g6 31. Rd2 Rxe4 32. dxe4 Qxc4 33. Rbd5 Nc5 34. Bxc5 bxc5 35. e5 Re8 36. h4 Re7 37. R5d3 Qc1+ 38. Rd1 Qc2 39. R1d2 Qc4 40. Kf2 Rf7 41. Kg1 Qe4 42. Kh2 Re7 43. Rc3 Rxe5 44. Rdc2 Rf5 45. Rxc5+ Rxc5 46. Rxc5+ Kb7 47. Rb5+ Ka6 48. Rg5 Qb1 49. Rd5 Qxa2 50. Rd7 Qb2 51. Rd6+ Ka5 (depth 61, 10:21:06)
the final position in the 14. Bh3 line is a draw. While SF says -1.74.

AB game rollouts to evaluate this gambit are not reliable.
Indeed, the final position in the 14. Bh3 line is a draw. But what about the position after 47. Rxf5 ?



So, as ever, deep A/B searches from the root are not definitive. Nonetheless, it's hard to imagine that this gambit gives White any winning chances. Unless Black is a human.
Ah! I thought I was trying to prove at least a draw for white, not a win.

I would go back further. After 32 ... b5 33. Nb5+ Kb6 now Rf6! not Bxg5

Rf6 Rxf6 exf6 Rxh4 Bxe6 Rxe4 Bd8+ Ka6 dxe4 Qxe4 Kg1 Qe1+ Kg2 Qe2+ Kg3 Qxd8 f7 and fortress which SF cannot see.
One thing that comes to mind is the vital importance of good static evaluations of near-tablebase positions. Now that engines search so deeply, they end up "making their plans" out of the opening based on very shallow searches of endgame positions at the leaves of a deep tree. This seems like an area where Stockfish, for example, could improve a lot.
So the Bryntse Gambit is good for at least a draw. *If* white knows what he is doing, plays according to sound positional themes and understands how to take advantage of pawn and minor piece cooperation. The SF (and other AB engine) evaluations of the imbalanced lines are just mostly wrong and overoptimistic. Those lines are very very positional.

Re: The Bryntse Gambit

Posted: Thu May 16, 2019 1:59 pm
by chrisw
jp wrote:
Thu May 16, 2019 10:27 am
chrisw wrote:
Thu May 16, 2019 10:16 am
zullil wrote:
Thu May 16, 2019 9:56 am
One more iteration. Now Bh3 is preferred:
-1.74 14. Bh3 Bxe5 ... 53. Kd2 Kxe6 (depth 61, 10:21:06)
the final position in the 14. Bh3 line is a draw. While SF says -1.74.
AB game rollouts to evaluate this gambit are not reliable.
I haven't seen it yet, but the very end of the line won't be reliable. It's way beyond 61 plies. What about at move 45 or 35?
Yes, well that's fine, but the line picked out by Stockfish, including the first move, is entirely dependent on these unreliable evaluations at the leaf nodes. That's not to say the first move is not the best move, it is to say that you can't rely on the score, and therefore can't assess the Gambit by some few monte carlo AB program rollouts.