Author: Tom King
Date: 14:43:31 01/02/01
Go up one level in this thread
On January 01, 2001 at 23:02:44, Jon Dart wrote: >I've recenty been looking at a couple of endgame positions. The first >one is from a game Arasan played against GM Karen Asrian: > >[D] 8/8/r1B2k2/4p3/4K2p/5N2/8/8 w - - > >Arasan played Nxe5, which Crafty seems to think is losing. It goes to a >large - score right away: > > Searching only the move played in game.-------------------- > time surplus 0.00 time limit 45:00 (45:00) > nss depth time score variation (1) > 9 0.22 -- 59. Nxe5 > 9 0.43 -2.35 59. Nxe5 h3 60. Ng4+ Kg5 61. Bd7 Ra2 > 62. Kd3 h2 63. Nxh2 Rxh2 64. Kc4 > 9-> 0.43 -2.35 59. Nxe5 h3 60. Ng4+ Kg5 61. Bd7 Ra2 > 62. Kd3 h2 63. Nxh2 Rxh2 64. Kc4 > 10 0.66 -2.50 59. Nxe5 h3 60. Ng4+ Kg5 61. Bd7 Ra2 > 62. Kd3 h2 63. Nxh2 Rxh2 64. Kc4 Kf4 > 10-> 0.66 -2.50 59. Nxe5 h3 60. Ng4+ Kg5 61. Bd7 Ra2 > 62. Kd3 h2 63. Nxh2 Rxh2 64. Kc4 Kf4 > 11 2.12 -2.55 59. Nxe5 h3 60. Ng4+ Kg5 61. Bd7 Ra7 > 62. Nf2 Rxd7 63. Nxh3+ Kg4 64. Nf2+ > Kg3 65. Nd3 Rd6 > 11-> 2.12 -2.55 59. Nxe5 h3 60. Ng4+ Kg5 61. Bd7 Ra7 > 62. Nf2 Rxd7 63. Nxh3+ Kg4 64. Nf2+ > Kg3 65. Nd3 Rd6 > 12 2.86 -2.55 59. Nxe5 h3 60. Ng4+ Kg5 61. Bd7 Ra7 > 62. Nf2 Rxd7 63. Nxh3+ Kg4 64. Nf2+ > Kg3 65. Nd3 Rd6 66. Nf4 > >Some versions of Arasan will switch off Nxe5 here eventually and play Bd7 or >Bb5, but the latest version selects Nxe5 after 10 minutes of search, with a >score of about -1. It could be a bug, but Hiarcs also seems to prefer Nxe5. >The game was eventually drawn, by the way. Latest, experimental, version of my program chooses Bd7 after 2 seconds, and sticks with it. > >The other position is from a game against another program (ChesterX on >ICC): > >[D] 2n5/8/1p6/pK5p/2N2k1P/8/PP6/8 w - h6 > >Here Chester played a4, but the sac Nxb6 seems to be winning. It is not >easy to find. Crafty fails high at ply 17, after almost 5 minutes of search >(on a PIII/733): > > 17 4:53 ++ 48. Nxb6!! > 17 5:20 1.49 48. Nxb6 Nxb6 49. Kxb6 a4 50. Kb5 Kg3 > 51. Kxa4 Kxh4 52. b4 Kg4 53. b5 h4 > 54. Kb4 h3 55. b6 h2 56. b7 h1=Q 57. > b8=Q Qd5 > (2) 17-> 5:24 1.49 48. Nxb6 Nxb6 49. Kxb6 a4 50. Kb5 Kg3 > 51. Kxa4 Kxh4 52. b4 Kg4 53. b5 h4 > 54. Kb4 h3 55. b6 h2 56. b7 h1=Q 57. > b8=Q Qd5 > 18 6:34 1.55 48. Nxb6 Nxb6 49. Kxb6 Kg3 50. Kxa5 > Kxh4 51. b4 Kg4 52. b5 h4 53. b6 h3 > 54. b7 h2 55. b8=Q h1=Q 56. Qc8+ Kf4 > 57. Qc7+ Kf5 58. Qc5+ Ke6 59. Kb5 > 18-> 9:01 1.55 48. Nxb6 Nxb6 49. Kxb6 Kg3 50. Kxa5 > Kxh4 51. b4 Kg4 52. b5 h4 53. b6 h3 > 54. b7 h2 55. b8=Q h1=Q 56. Qc8+ Kf4 > 57. Qc7+ Kf5 58. Qc5+ Ke6 59. Kb5 > 19 11:39 1.55 48. Nxb6 Nxb6 49. Kxb6 Kg3 50. Kxa5 > Kxh4 51. b4 Kg4 52. b5 h4 53. b6 h3 > 54. b7 h2 55. b8=Q h1=Q 56. a4 Qc6 > 57. Qb5 Qc7+ 58. Kb4 Kf3 > >I'd be interested in any analysis or comments on these positions from other >players or programs. > >--Jon Mine chooses a4 immediately. It needs just under 290 secs, and an 18 ply search (on a celeron 500) to see than Nxb6 is good. Ugh. Tablebases would be useful for both positions, methinks. Rgds, Tom
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