Author: Robert Hyatt
Date: 14:27:44 11/16/98
Go up one level in this thread
On November 16, 1998 at 16:40:57, Ernst Walet wrote:
>On November 16, 1998 at 14:50:57, Bruce Moreland wrote:
>
>>r1r1q1k1/6p1/p2b1p1p/1p1PpP2/PPp5/2P4P/R1B2QP1/R5K1 w - - 0 1
>>
>>It has been contended that this move would be difficult for a computer to find,
>>and this has caused some doubts to be raised as to whether the computer found it
>>without assistance in this game.
>>
>>I would like to ask how we can clear this up absent input from DB.
>>
>>Has anybody run this for a long period on a micro, and if so, was any move
>>selected other than 35. Qb6?
>>
>
>Aren't we talking about move 36 here? I ran this position on a K6-266 with
>Tascbase 2.1 and after about 6 hours, completing ply 15, it still plays Qb6 with
>a score of +1.31.
>
>Shall try to find out how it evaluates axb5.
>
>>Is the counter-attacking line 35. Qb6 Qe7 36. axb5 Rab8 37. Qxa6 e4 supposedly
>>the reason that white shouldn't play 35. Qb6? Or is it some other line? If it
>>is too hard or impossible to find 35. axb5, would finding this line show
>>anything?
>>
>>Is there some minimum score delta we can achieve between the position after 35.
>>axb5 and 35. Qb6 that might be evidence that DB should be given the benefit of
>>the doubt?
>>
>>Are these questions unfair or wrong, if so, are their other questions that can
>>be asked and possibly answered that will help clear this up?
>>
>>bruce
>
>Ernst-Jan
I ran this to extreme depth with crafty, about 1 hour for each search, and
got the following:
For axb5:
17 66:28 0.32 1. axb5 axb5 2. Qb6 Rxa2 3. Rxa2 Ra8
4. Rxa8 Qxa8 5. Qxd6 Qa1+ 6. Kh2 Qc1
7. Qe6+ Kh7 8. d6 Qf4+ 9. Kg1 Qc1+
10. Bd1 Qxd1+ 11. Kh2 Qc1 12. d7 Qf4+
and for Qb6:
16 56:28 1.51 1. Qb6 Rd8 2. Be4 Bf8 3. Qe6+ Qxe6
4. fxe6 Rab8 5. axb5 axb5 6. Ra7 Re8
7. Kf2 Rbd8 8. g4 Bd6 9. R7a5 Rb8 10.
Ra7
So this version likes Qb6 by a significant margin. Older versions close this
gap to 1/4-1/3 pawn, but they were more king-safety-exaggerated types of evals.
The above is from a single pentiumpro machine, searching only the move asked
for...
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