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Subject: Re: Please explain the difference between PVS and NegaScout

Author: Ernst A. Heinz

Date: 12:30:30 03/05/01

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Hi Severi,

>I really would like to know it...pretty please.

The original "Scout" and "NegaScout" algorithms consist of
_two_ separate functions that call each other recursively.
Their effect is the same as that of a standard PVS search.

Moreover, Reinefeld discovered that for _fixed-depth_ searches
(in the strict theoretical sense of the word, i.e., uniform
path lengths from the root to _all_ leaf nodes) researches
after fail-highs of minimal-window searches are superfluous
if the remaining depth at the node in question is <= 2 plies.
The discovery was initially made and published in the
"Scout / NegaScout" rather than the PVS framework.

Reinefeld's discovery is of no practical importance, however,
as soon as you look at variable-depth searches as caused by
extensions and forward-pruning.

=Ernst=



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