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Subject: Question about aspiration window

Author: Inmann Werner

Date: 07:08:23 08/14/98


Question about aspiration window.

I use Aspiration alpha-beta.
For the first searched move on a ply in deeper depth, I set alpha=oldbestvalue-x
and beta=oldbestvalue+x
Nothing unnormal.

Now I found some positions, where my program lowers the evaluation of this first
move of a ply (till now the best!) always with x. (see above)
If I change x, it is the same until x gets really high, and i get a "true"
value.

The disturbing thing on it is, that one ply deeper, the program should recognice
how bad this move really is, but it does not make a fail low! (If I get a fail
low, I research with open window)

I removed hashing and null-move, but it is the same.
If i search the first move of a ply with a full window, everything gets ok, but
slow!

I am sure, it is a failure in my thinking of aspiration alpha beta.
Has anybody an idea, what could be wrong, where I could search the failure?

Werner



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