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Subject: Re: Fill & Floodfill (for Gerd)

Author: Bas Hamstra

Date: 09:07:14 12/24/02

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On December 23, 2002 at 23:32:14, Russell Reagan wrote:

>On December 23, 2002 at 19:33:50, Bas Hamstra wrote:
>
>>What is the
>>definition of backward pawn, in fact?
>
>A backward pawn is just one type of weak pawn. A weak pawn is a pawn that cannot
>be defended by other pawns, and thus requires pieces to guard it. Those pieces
>in turn become less active and more restricted.
>
>I think it's a better idea to avoid thinking of "backward pawns" or "isolated
>pawns" or "doubled pawns", but rather to focus on the weakness of the pawn
>structure more generally (if you're wanting a "perfect" method). For example, it
>would probably be better to have a function that detected whether or not a pawn
>was weak (unable to be defended by fellow pawns), rather than detect doubled
>pawns and tack on a penalty, because doubled pawns, just like isolated and
>backward pawns, are not always weak.
>
>I suppose since it is possible for an isolated pawn to not be weak, that a
>better "weak" pawn definition is "a pawn that requires the support of pieces."
>As with most things in chess, detecting this statically is not going to be
>perfect.

I agree, but even this is not trivial. Because I would like to know certainly
more than if a pawn needs pieces to defend it. Most importantly: will it need
pieces to defend it practically forever. And so you need to know:

- is the pawn pawn-defendable where it is
- can it advance to a place where it is pawndefended. To do so, there must me no
blocking pawn or opposing pawn domination in the way.

Not easy, but I am working on it.

- - - - - - - -
B - - - - - - -
W - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
- W - - - - - -
- - - - - - - -

The white b-pawn cannot ever become pawn-defended. I intend to treat it as weak.

- - - - - - - -
B - - - - - - -
W - - - - - - -
- - - - - - - -
W - - - - - - -
- - - - - - - -
- W - - - - - -
- - - - - - - -

But now it could be, in principle, so not weak.

- - - - - - - -
B - - - - - - -
W - - - - - - -
- - B - - - - -
W - - - - - - -
- - - - - - - -
- W - - - - - -
- - - - - - - -

Weak again. As long as a pawn stays where it is, I can tell if it is
pawn-defendable, now I want the others cases too. This would result in an
element of look-ahead I hope.

Best regards,
Bas.







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