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Subject: Re: negative extensions

Author: Peter McKenzie

Date: 11:11:36 01/25/01

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On January 25, 2001 at 08:20:26, David Rasmussen wrote:

>Howdy.
>
>Inspired by the thread on extensions, I was wondering whether the idea of
>negative extensions or reductions could be a good one.
>
>I mean, maybe many of the "unsound" pruning methods would be sounder if, instead
>of just pruning, they just adjusted the resulting depth down. In that way, a
>line would still be examined, only later.

Hi, in the past I have thought of negative extensions too although I haven't
tried implementing them yet.  I wouldn't consider nullmove to be a negative
extension, its not really in the spirit of an extension - I'd just call it a
pruning method.

In my mind, extensions are usually a move based thing.  By this I mean that we
can see some property of the move we have just played (or are just about to
play, depending on exactly how you implement the extension) which indicates that
we should extend.  Obvious examples are
- check extension
- recapture extension
- single response extension
- passed pawn push extension

So the question is, what sort of moves could be candidates for a negative
extension?



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