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Subject: Re: Game from US correspondence championship finals

Author: blass uri

Date: 14:13:47 03/16/00

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On March 16, 2000 at 14:02:28, Robin Smith wrote:

>On March 15, 2000 at 15:08:36, blass uri wrote:
>
>>On March 15, 2000 at 14:17:59, Robin Smith wrote:
>>
>><snippped>
>>>In the 13th US correspondence chess championship finals I played a move that my
>>>computer NEVER finds.  Do any programs find 17.... Qd5!
>>>
>>>This move prevents white from playing Be4 (which would put presure on b7 and
>>>support a possible d pawn push), it frees d8 for blacks rook and it keeps the
>>>queen eyeing d5, restraining whites isolated d-pawn.  I believe it is the
>>>strongest move in the position, but when I reviewed the game with my computer it
>>>never finds it even after a very long "think" because of the exchange sac
>>>involved.
>>
>>Did you try to generate a tree with the computer to prove that 17...Qd5 is
>>really the best move?
>
>I don't know how to "prove" that a positional move is best.  I do know that it
>seems programs reject it out of hand because of a faulty "refutation" ... the
>game continuation.


Computers always prove that a move is best by a tree.
one of the problem of programs is that they do not know to do the right
extensions.

I can generate a tree and prove by telling programs to give me more than one
option that there is no good move out of the tree.

I can calculate the best move based on the evaluations after search of the
leaves of this tree.

If the best move based on these evaluations is Qd5 I see it as a proving tree
that Qd5 is best.


>>It is clear that after 19.Nb6 white is losing but the question is if white has
>>no good alternative before(for example 18.f3)
>
>18.f3 is maybe better than what white played, but white's exposed king, weak
>d-pawn and blacks 2 bishops are very strong strong advantages.  Either 18.f3 Rd8
>or 18.f3 Qg5 should give black a winning position.

You may be right about f3

I did not analyze f3 for a long time because it was not my game.
I got with Junior5.9 a better score for black by 17...g6 relative to 17...Qd5
18.f3 and this was the reason that I suggested this move but I see that the
Junior5.9 intends to play the same wrong idea of Qa4 Be7 Nb6 after 18.f3 Rd8

The point is that I cannot be sure that black is winning without analyzing a lot
of lines with the computer.

Uri





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