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Subject: Changing Score at Horizon, after finishing Q-Search? Alpha/Beta Values?

Author: Johannes

Date: 04:37:55 04/06/05


Hello!
Right now im working on a new Version of my Chess Engine and an idea has come to
my mind, but i dont know if its applicable:
When I'm in Q-Search i only want to deal with material values. I handle theses
incrementally, so theres is no need for any function call except the Q-search
recursion.
After returning from Q-Search (at the full-width horizon) i simply add the
positional eval score to the score returned from Q-search. This score is
returned "up the tree".
For the positions before the horizon this should be no problem concerning
alpha/beta values etc... . Also positions beyond the horizon should not suffer
from this, as long as the alpha/beta values were not passed to a Node before the
horizon before. If they were, the alpha/beta bounds would not be correct,
because they include positional scores which are not considered beyond the
horizon.
So my idea is to simply substract the local positional score from the alpha/beta
values (as long as they are not -INF or +INF) at the full-width horizon, before
entering Q-Search. I assume that this would result in correct cutoffs.
Is this idea correct?
I didnt find any drawbacks yet, but i only have a vague intuition about it.
I really would appreciate if anybody could help me with this.
greets
johannes





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