optimal aspiration window for stockfish question

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lucasart
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Re: optimal aspiration window for stockfish question

Post by lucasart » Sun Mar 18, 2012 5:55 am

bob wrote:
mcostalba wrote:
bob wrote: I'm beginning to think that the +/- infinity idea is just as good as aspiration search. Most likely because we all use PVS (null-window, not null-move) anyway. I did not go all the way to infinity in my test results I posted here, but I will try it to see if it makes any difference. (I suspect there will be no change at all).
A little detail: aspiration window should not start from iteration 1, in Stockfish it starts from iteration 5 and before we use +-inf.
Why would it matter? Those iterations take microseconds to complete. Doesn't matter how many re-searches you do down there...
I confirm what Robery is saying. I've done some testing in DoubleCheck with that, and found the minimum depth condition to be useless. However, if it doesn't help, it cannot hurt, and it reduces the nodecount on a "./DC bench" (I haven't tried with "./stockfish bench" but I'm almost certain it's the same). But I kept the condition anyway, as it may have an impact at stupidly fast games (sometimes I test without time control and just a node limit of 50k nodes for example).

But there is another condition in StockFish which might make more sense. If the score is a mate score (or a winning endgame by EG knowledge which returnsd high scores) then SF doesn't do aspiration. I haven't done any serious measurement on that, but it makes sense. Although I expect no elo improvement from it, it should make SF waste less time in researches when it's finding a mate, which is nice for analysis.

zamar
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Re: optimal aspiration window for stockfish question

Post by zamar » Sun Mar 18, 2012 9:02 am

lucasart wrote: But there is another condition in StockFish which might make more sense. If the score is a mate score (or a winning endgame by EG knowledge which returnsd high scores) then SF doesn't do aspiration. I haven't done any serious measurement on that, but it makes sense. Although I expect no elo improvement from it, it should make SF waste less time in researches when it's finding a mate, which is nice for analysis.
We don't want to use aspiration search in endgame like KBNK, because TT is filled with mate scores.
Joona Kiiski

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