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Subject: Re: PVS or AlphaBeta? Anyone using AB?

Author: William H Rogers

Date: 15:33:47 10/27/99

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On October 27, 1999 at 15:38:54, Frank Schneider wrote:

>Hi all,
>
>this is a question about the searchalgorithms used by other programs.
>Many programs and also Gromit seem to use PVS or MDT(f) which both use
>nullwindow-searches.
>Is there anyone using a search that doesn't do nullwindow searches?
>Why? Why not?
>
>
>Frank

I may be wrong, but I think that the PVS is used to find quicker cutoffs in
alpha/beta.
Such as:

1.e2e4   1. e7e5  2.g1f3  2.g8f6

this is a bad example, but, g1f3 would be your PVS for move two, so if the
opponent makes move 1. e7e5 then you can assume that you are going to follow the
PVS and make 2.g1f3 and so on. It anticipates your opponents move and thus can
speed up your program.
This is also used to think on your opponents time, assuming that he makes the
move that your program predicted. You search forward until he makes a move, then
check it to see if it matches your predicted move, if so then you can continue
searching a little deeper. If not you start your search from scrach.
Bill



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