UCI score lowerbound/upperbound w/ aspiration windows

[fluxroot]

Hi there!

Does anybody know how to use the UCI score lowerbound/upperbound commands with aspiration windows?

E.g. you have a window 40+-20 and you fail low (< 40-20 = 20). What do you output? If you would output score cp 20 upperbound this would be wrong if you extend the window say 40+-100 and the search's coming back with 30. So 20 would not be an upperbound.

How do you implement those commands?

Cheers,
Poky

[Onno Garms]

I thought that somebody else might be more competent to answer, but as nobody did, here is what I think:

If you search first fails low with a window 40 +- 20, i.e. alpha=20, beta=60, and later comes back with 30, this is search instability. If this happens too often, you should look for methods to stabilize your search (or even look for bugs). However, search instability cannot be avoided completely without making too many concessions.

The engine should report this by first reporting upperbound of 20 and then returning 30. The engine can only report what it knows when reporting.

[fluxroot]

Thanks for your response!

That's exactly what I thought. Because I cannot eliminate the search instability (or could I?) I have to face the problem printing a wrong upperbound.

I think I go along with printing the upperbound anyway. Thanks again for the answer.