Author: Jon Dart
Date: 13:51:09 05/12/03
[D] 7r/4k3/5bRP/5P1P/5K2/8/8/8 w - -
The move to avoid is Rg7+. It appears that other moves, e.g. Kf3, draw, but Rg7+
loses. This occurred in a game, so it's not just theoretical.
Ability to solve this is related to the use of null moves. Arasan 5.4 apparently
never switches off Rg7+, but if null move is disabled, it won't play it.
Arasan 6.3 switches off Rg7+ eventually but it takes quite a while (113 seconds
on a Xeon 1.7GHz).
Crafty does not ever want to play Rg7+, but in analysis mode, it takes a long
time to see that this is not a good move:
Searching only the move played in game.--------------------
time surplus 0.00 time limit 24:00 (24:00)
depth time score variation (1)
10 0.33 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
10-> 0.33 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
11 0.72 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
11-> 0.72 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
12 2.17 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
12-> 2.22 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
13 5.28 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
13-> 5.28 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
14 15.24 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
14-> 15.24 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
15 39.46 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
15-> 39.46 0.00 135. Rg7+ Kf8 136. Rg2 Kf7 137. Rg6
Ke7
16 50.61 -- 135. Rg7+
16 2:03 0.00 135. Rg7+ Bxg7 136. hxg7 Ra8 137. Kg5
Kf7 138. f6 Ra1 139. Kf5 Rg1 140. h6
Rf1+ 141. Kg4 Rxf6 142. Kh5 Rxh6+ 143.
Kxh6 Kg8 144. Kg5 Kxg7
16-> 2:03 0.00 135. Rg7+ Bxg7 136. hxg7 Ra8 137. Kg5
Kf7 138. f6 Ra1 139. Kf5 Rg1 140. h6
Rf1+ 141. Kg4 Rxf6 142. Kh5 Rxh6+ 143.
Kxh6 Kg8 144. Kg5 Kxg7
17 2:03 -- 135. Rg7+
17 5:37 -1.95 135. Rg7+ Bxg7 136. hxg7 Ra8 137. Kg5
Kf7 138. f6 Ra2 139. Kg4 Rg2+ 140.
Kf5 Rg1 141. h6 Rh1 <HT>
17-> 5:37 -1.95 135. Rg7+ Bxg7 136. hxg7 Ra8 137. Kg5
Kf7 138. f6 Ra2 139. Kg4 Rg2+ 140.
Kf5 Rg1 141. h6 Rh1 <HT>
--Jon
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