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

Author: Martin Giepmans

Date: 16:17:47 08/08/01

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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.


>>(2) The influenced score is stored in the hashtable and used in the next
>>calculation, after the opponent has moved.
>>(There is no problem if the scores are used in this calculation)
>>
>>Proposition: Cutting off based on "old" hashtable scores is nonsense.
>>
>>Rip it out! :)
>>(I did)
>
>Put it back.  Even if your first contention were correct, is an unstable large
>tree worse than a stable smaller one?
>
>The winner in a hot-dog eating competition is not necessarily the most
>fastidious.  A certain amount of mustard in your hair is alright if you get the
>most dogs down.
>
>bruce
>
>>
>>Martin


Well yes, but is the tree really smaller? In the endgame the program with "old
cutoffs" is sometimes faster, sometimes slower. Overall the gain is not clear.
In the middlegame there is usually no significant difference, but in some of my
testpositions the old stuff slows the program down and the output shows
instability. Too much mustard on the hotdogs perhaps ...
Of course a lot depends on the environment (eval etc.). Maybe program A benifits
from old cutoffs and program B doesn't benifit. That's always the problem.

Martin





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