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Subject: Re: Trapped Rook

Author: scott farrell

Date: 06:40:47 12/04/02

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On December 03, 2002 at 13:44:21, Colin Frayn wrote:

>Here's an interedting position that arose in an ICC game between Beowulf and a
>human player.  it's one of those positions where Beowulf knows it's behind, but
>can't possibly realise how bad his position is because he doesn't realise how
>his h7 rook is utterly trapped.
>
>[D]r4k2/2R2p1r/4pBp1/4P2p/pR3P1P/Pb2K1P1/8/8 b - -
>
>I'm not sure how to get round this without adding in some hideously slow code.
>I already have mobility code in for the rook but then it's difficult to
>distinguish between a rook that's in a nice defensive position that it could get
>out of and which will transform itself into an open file fairly quickly after a
>pawn exchange, and something like this where there is no sequence of moves to
>retrieve the rook from its corner.
>
>Cheers,
>Col
Here is some unconventional wisdom (?)

I have thought about this sort of idea quite a lot.

It appears to me that this rook problem, is one of a whole class of similar
problems.

One I saw was in Kramnik vs Fritz games of recent is where the fritz rook was
not trapped or pinned, but couldnt move away, as it had to defend a pawn, but
effectively trapped based on human observation. Kramnik has such a decisive win
from here, it was amusing to watch.

It occured to me, that a search SHOULD be able to see this, my logic goes like
this:

1) do a normal search
2) find how many rook moves result in some sort of failure (null-move, futility,
etc etc)
3) score that piece down if there are a too large a penalty for moving that
piece

There are HUGE practical problems obviously:
4) everyone scores quiet positions
5) this requires scoring pieces through a dynamic sequence, and attributing the
score back to a piece on a board towards the root somewhere
6) the need to recognize the rook (or other piece) as being 'trapped' and
somehow tagging this is NOT quiet, and doing a 'trapped' search as opposed to a
'qsearch'

now if I could only code as fast as I can think after a few beers with the lads.

Scott



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