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Subject: Re: "Don't trust draw score" <=Is it true?

Author: Tony Werten

Date: 07:30:59 08/10/01

Go up one level in this thread


On August 09, 2001 at 06:12:52, Martin Giepmans wrote:

>On August 09, 2001 at 02:39:53, Bruce Moreland wrote:
>
>>On August 08, 2001 at 19:17:47, Martin Giepmans wrote:
>>
>>>On August 08, 2001 at 17:18:02, Bruce Moreland wrote:
>>>
>>>>On August 08, 2001 at 16:43:39, Martin Giepmans wrote:
>>>>
>>>>>Yes, I see your point. Now the question is: is there always pollution?
>>>>>I think 2 conditions are necessary:
>>>>>(1) The score (+0.20) is influenced by a drawscore that is based on *external*
>>>>>repetition.
>>>>>(There is no problem with the influence of internal repetition)
>>>>
>>>>No, this is false.  You can get to the same position at the same depth in the
>>>>same iteration, and have subsequent moves with different repetition
>>>>consequences.
>>>>
>>>I don't see how this could have a negative effect, if you do not use cutoffs
>>>based on drawscores from the hashtable.
>>
>>Everything I have said in my posts in this thread is an attempt to show that
>>draw scores that you encounter influence other scores.
>>
>>bruce
>
>
>I understand what you are trying to say. Let's illustrate it with a (simplistic)
>example:
>Path A: 1. Nf3 Nf6  2. d4  d5
>Path B: 1. d4  d5   2. Nf3 Nf6
>Same position (P).


Suppose these moves happen a little later in the game.

After whites first move, it could have been a draw in A because of a 50 move
rule, but not in B.

cheers,

Tony

>The program first takes path A and discovers that Ng1 is the best move in P
>(you need a weird static eval for that, but ok), score +0.40.
>Now the program takes path B. Is Ng1 the best move? No, black plays Ng8
>and repeats the position after d4 d5. Score 0.00.
>The best move is, say, Nc3. Score +0.10.
>
>I think this proves your point: drawscores influence other (nonzero) scores.
>However, along path B white has obviously not played the best moves.
>If white gets 0.10 instead of 0.40 there must be something wrong with either 2.
>Nf3 or 1. d4 or both.
>So, my question is: does this influence of drawscores minimax downto the root of
>the tree? My first thougth was no, my last (thought 31) is: I really don't know
>...



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