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Subject: Re: The Limits of Positional Knowledge

Author: blass uri

Date: 00:40:04 11/26/99

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On November 25, 1999 at 18:53:19, Amir Ban wrote:

<snipped>
>Maybe the reason you didn't get real replies to your question is that you are
>asking a really good question.
>
>I identify with you, because I've been asking myself the same question during
>the last year. Most of the effort that went into Junior 6 was spent on
>systematic improvement of the program's evaluation. I spent on this much more
>time than I spent, say, on the Deep Junior (SMP) code.

Did you add more knowledge or only changed parameters?
Did Junior become slower because of the improvement in the evaluation?

We cannot know it by nps because it is possible that you found ways to do the
same thing faster.

I have only Junior5.9 but I see that there are some negative effects of changing
the evaluation function.
For example it cannot find Junior's sacrifice against nimzo thanks to reducing
the value of the pawn(on the other hand it can avoid the famous mistake Qxg7 of
zunzwang against a human and can sometimes find pawn sacrifices for initiative).

I see that there are simple things that crafty knows and Junior does not know
For example about cases when KBPP vs K is a draw if the white bishop does not
control the h8 corner and the pawns are on the h file and the black king can go
to the corner h8(this can be solved by tablebases but if black has a pawn or a
knight then tablebases of today cannot help).

Did you decide not to add a some knowledge because you were afraid of doing the
program slower?

 While doing this effort I
>often wondered whether this is really an effective way of taking the program one
>level higher, and at other times I wondered what will be the limit of this
>approach. I'm not sure what the answers are, but you will be able to see the
>effect in Junior 6 as compared to Junior 5, though I did spoil the clean
>comparison somewhat by changing other things.

I think that you are not close to the limit of this approach becuase there are
many things that Junior does not understand.

In my analysis of my correspondence games I can see often cases when Junior
evaluates the position as +1.00 and can make no progress.

I found in one of my correspondence games a case when there was a clear
difference between Junior's evaluation and hiarcs's evaluation  and Hiarcs was
right(of course there are also cases when the opposite happens)

Uri




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