Author: Dan Homan
Date: 11:57:17 03/30/98
Go up one level in this thread
On March 30, 1998 at 13:09:34, Jon Dart wrote:
>Recently my program "Arasan" played a game on FICS against
>"noro", and reached the following position:
>
>8/8/5R2/r5P1/8/p5P1/K5kP/8 b - -
>
>Here the computer played Rxg5 and eventually lost. It appears
>that Kxh2 draws (Crafty finds Kxh2 right away. The analysis
>goes Kxh2 g6 Rg5 Kxa3 Kxg3 Kb4 Kg4 Kc4 Kh5 Kd4 Rxg6).
>
>This isn't really hard, but it helps if the program knows
>the passed pawn is not dangerous even though the king is
>behind it. It looks to me like Crafty has special case
>code for just this ending (in EvaluatePassedPawns).
>Genius 5.0 also likes Kxh2 after a short search. I'm
>wondering if any other programs find this difficult.
>
>--Jon
My program likes Kh2 at first but quickly switches to Rxg5.
Here is the search output for 1 minute of thinking on an older
175 MHz Alpha. I don't have much endgame specific knowledge in
my evaluation yet...
Black(1): analyze 60
1. -127 0 4 a5g5
1. ++ 0 6 g2h2
1. -51 0 7 g2h2
2. -59 0 69 g2h2 f6f3
3. --
3. -157 0 1057 g2h2 g5g6 h2g3 g6g7
3. -127 0 1263 a5g5 a2a3 g2h2
4. -135 0 2421 a5g5 a2a3 g2h2 f6f3
5. ++ 0 5506 a5g5
5. -13 0 7450 a5g5 a2a3 g2h2 f6f3 g5g3
6. -8 1 12699 a5g5 a2a3 g2h2 a3b4 h2g3 f6f1
7. --
7. -59 1 39807 a5g5 f6h6 g5a5 g3g4 g2f3 h6h3 f3g4
h3a3 a5d5
8. -59 2 64748 a5g5 f6h6 g5a5 g3g4 g2f3 h6h5 a5a4
h5h3 f3g4 h3a3
9. -72 3 110847 a5g5 f6h6 g5a5 g3g4 g2f3 g4g5 a5g5
a2a3 g5a5 a3b3
10. -89 7 243493 a5g5 f6h6 g5a5 g3g4 a5a4 g4g5
11. -113 15 495857 a5g5 f6h6 g5a5 g3g4 g2f3 g4g5
12. -137 27 948392 a5g5 f6h6 g5a5 g3g4 g2f3 g4g5 a5g5
a2a3 g5b5 h2h4
13. -136 52 1822365 a5g5 f6h6 g5a5 g3g4 g2f3 g4g5 a5g5
a2a3 g5d5 a3b4
node_count = 2075637 quiescent nodes = 124552 eval_count = 640296
hash hits = 554789 hash moves = 90934 pawn hash hits = 639887
node_rate = 34593 null cuts = 165339 exten = 110774 int_iter = 18
- Dan
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