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Subject: Re: Testing the quality of order of moves in a correct way

Author: Richard Pijl

Date: 09:51:38 11/26/02

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[snip]

>I can explain reasons that the best move can give a smaller tree.
>
>I have a pruning based on evaluation and other factors.
>The best move may lead to search to reduced depth because of this pruning.
>
>Even programs that only use null move pruning may have search to reduce depth
>based on this reason because after the best move it is more common to have a
>cutoff because of no threat for the opponent.

This size of the subtree below the first move matters more than the height of
the eval.
Probably made clear the best by an extreme example:

Suppose the best move will result in a quiet position. The moves leading to that
position are all quiet moves. Alternatives to the PV moves are probably just as
good.

But now an alternative. This move leads to a PV with many checks and capture
moves. Although the endposition is slightly inferior to the PV described above,
the resulting score is still above beta. The tree for this move is much smaller
than the tree for the best move.

Well, I agree this is an extreme example, but I think you may see many of those
cases where the smallest tree needed for a cutoff does not start with the best
move. A good capture move may even be good enough

Richard



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