Author: Jon Dart
Date: 20:02:44 01/01/01
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.
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
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.