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

Author: Severi Salminen

Date: 05:08:21 03/06/01

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>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.

Thank you! Now I'm using the basic PVS search: search the 1st move with normal
window and the rest with minimal window and research using the score from 1st
search as a bound. I somehow thought that S/NS would be somekind of improvement
over that but as I also extend/prune/qsearch I think I don't need it.

Severi



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