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Subject: Re: Exact value of second best move in AlphaBeta with aspiration Window

Author: Ulrich Tuerke

Date: 05:12:13 08/01/02

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>
>I think that comes from AlphaBeta, where it is enough to be lower than
>bestvalue, no interest in "how much", am I right?

That's correct. Alpha-beta gives for the best only an exact score; the remaining
values are upper bounds.

>
>I there a poosibility to get a better Value at the root node for secondbest move
>with a specific searchdepth?

In order to get exact values, you in principle have to switch off alpa-beta at
ply 1. But that's too expensive in terms of search tree sizes.

>
>while iterative deepening at the root node (for distance  := 1 to
>SearchDepth...) I want to ask something like this:
>
>IF (distance = 7) AND (BestValue < SecondBestValue+3*PawnValue) THEN dont waste
>to much time in thinking...
>
>But as I described, even if there is only 1 possibility to recapture a queen the
>values are close together, for exaple 900, 897, 995 ...
>
>any Ideas?

I do a pure minmax search at iteration #1. So, I get exact values at this level.
These values - combined with other criteria - are some measure whether the best
move is "an easy one".

Uli

>
>Bye
>
>Martin



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