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Subject: Re: Position Evaluation vs Selective Search

Author: Bo Persson

Date: 10:13:21 11/20/00

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On November 20, 2000 at 12:14:57, Bob Durrett wrote:

>On November 20, 2000 at 11:55:10, Bo Persson wrote:
>
>>On November 20, 2000 at 11:06:46, Bob Durrett wrote:
>>
>>>Would it be possible to evaluate a position so well that only one next move
>>>would need to be considered?  In that case, "selective search" would not involve
>>>any selection at all [i.e. nothing to chose between].  The "selection" would be
>>>done during the position evaluation.  In the limiting case, only ONE line would
>>>need to be evaluated, except in the cases when two or more moves were found
>>>[during the position evaluation] to be of equal value.
>>
>>If it was possible, you would have solved chess!  :-)
>>
>>Just let the program run from the start position, and see if it comes up with
>>e2-e4 or d2-d4 as the optimum opning. Repeat for 40 plies and you end up in a
>>check mate for white (or a draw??).
>
>You are assuming that one or the other of 1.e4 or 1.d4 is the better move.
>Maybe not a valid assumption!

Of course we don't know for sure, as the evaluator isn't finished yet. I would
be *very* surprised if it was 1.a3 instead.

>Incidentally, the position evaluation software may have to declare two or more
>moves "equal" if they appear to be reasonably close.  How "reasonably" would be
>defined in this case would be up to the programmer.
>>

My point was supposed to be that the current programs already *do* this
evaluation, by doing a lot of calculations for each potential move from the
position. The calculations are called "search".

From a program's point of view (if there ever is such a thing :-), there is
really no difference between performing a search and imagining what the search
result would be. Programming is all about abstractions anyway.


Bo Persson
bop@malmo.mail.telia.com



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