Author: J. Wesley Cleveland
Date: 10:23:57 05/30/01
Go up one level in this thread
On May 29, 2001 at 17:19:09, Robert Hyatt wrote:
>On May 29, 2001 at 14:21:13, Peter Fendrich wrote:
>
>>This position appeared in an ICC game: Guitje - TerraPi
>>
>>[D]2r3kb/5q1p/4pPp1/1p1pP3/p2P2Q1/PrP5/1P3R1R/2B3K1 w - - 0 42
>>
>>the last move from Terra was 41... b5
>>Some moves earlier when white made g6, Terra decided to move the bishop from g7
>>to h8.
>>Both Rb3 and Bh8 are locked in and Terra is absolutely unaware of the
>>hopeless situation. Yes, Terra lost...
>>
>>I see two different but connected problems for computer programs here:
>> - the closed position itself
>> - the two blocked pieces.
>>
>>How do you solve/avoid positions like this? Terra has about equal eval for this
>>position.
>>It is of course possible to punish pawn chains like this in order to avoid
>>closed positions but is that really a solution and how to deal with blocked
>>positions?
>>
>>//Peter
>
>
>First, this looks dead lost. I get big scores (>3) after a few seconds and 13
>plies.
>
>The position you gave is too late to repair. You have to recognize blocked
>pawns _before_ they are blocked, which means the 'mistakes' were made earlier
>in the game. I evaluate blocked pawns in Crafty, but I also evaluate pawn
>levers and make sure I keep a pawn break opportunity alive to avoid getting
>into totally closed positions...
>
>Here you should probably find Rxh7 is crushing of course...
I ran this position on crafty 18.3 and got this log. Between plies 13 and 14
there is an effective branching factor of almost 600. I know that fail highs can
cause big problems, but this seems extreme.
13 27.10 3.77 1. Rxh7 Kxh7 2. Qh4+ Kg8 3. Rh2 Bxf6
4. exf6 Kf8 5. Qh8+ Qg8 6. Rh7 g5 7.
f7 Qxh8 8. Rxh8+ Kxf7 9. Rxc8 g4 10.
Kf2 Kf6
13-> 34.05 3.77 1. Rxh7 Kxh7 2. Qh4+ Kg8 3. Rh2 Bxf6
4. exf6 Kf8 5. Qh8+ Qg8 6. Rh7 g5 7.
f7 Qxh8 8. Rxh8+ Kxf7 9. Rxc8 g4 10.
Kf2 Kf6
14 43.34 ++ 1. Rxh7!!
14 335:00 4.30 1. Rxh7 Kxh7 2. Qh4+ Kg8 3. Rh2 Bxf6
4. exf6 Kf8 5. Qh8+ Qg8 6. f7 Qxh8
7. Rxh8+ Kxf7 8. Rxc8 Kf6 9. Kg2 Kf5
10. Rf8+ Ke4 11. Rf4+ Kd3 12. Rf3+
Ke4 13. Kg3
14-> 335:22 4.30 1. Rxh7 Kxh7 2. Qh4+ Kg8 3. Rh2 Bxf6
4. exf6 Kf8 5. Qh8+ Qg8 6. f7 Qxh8
7. Rxh8+ Kxf7 8. Rxc8 Kf6 9. Kg2 Kf5
10. Rf8+ Ke4 11. Rf4+ Kd3 12. Rf3+
Ke4 13. Kg3
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