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Subject: Re: negascout and PVS?

Author: Russell Reagan

Date: 16:54:25 07/28/04

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On July 28, 2004 at 06:59:50, Fabien Letouzey wrote:

>Sorry, I can only repeast myself.
>In PVS/NegaScout only the *first* (= leftmost) is searched with a full window.
>This does *not* depend on the window.  If you want to implement it with a flag
>like Bruce's, set the flag after the first move.
>Bruce's property (his flag) depends on the window.

Okay, I have thought about it some more and looked at more code. I think I
understand now. The difference is when each version starts to search with a
minimal window, right?

Normal PVS:  Always searches with minimal window after the first move
Bruce's PVS: Only searches with minimal window after finding a move that
improves alpha

So at a node where alpha == -infinity, they behave the same at that node since
alpha is guarenteed to be improved after searching the first move. Do I
understand correctly now?

Okay, the next question is which version is better?

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