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Subject: Re: Static Eval: Scores for White !

Author: Gerd Isenberg

Date: 12:13:16 02/26/04

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On February 26, 2004 at 12:14:59, Vincent Diepeveen wrote:

>On February 26, 2004 at 04:23:01, Gerd Isenberg wrote:
>
>><snip>
>>>>To avoid the white versus side to move score chaos, it makes sense to mirror all
>>>>>current black to move positions vertically with white to move.
>>>>
>>>>Oups, with mirror vertically i mean white pawn on e2 becomes black pawn on e7
>>>>and so on.
>>>
>>>i prefer also left right mirrorring. I bet diep is one of the few programs still
>>>displaying the same score then :)
>>
>>A good point, with respect to castle rights of course.
>>In my current program there are some asymmetries in (early) middlegame :-(
>>
>>In my new approach i will implement FRC-castles, but mirroring castles (rights)
>>is still not possible since king/rooks target squares are still asymmetric.
>>
>>Gerd
>
>You're not getting my point exactly.
>
>Try some known testset positions at Fritz and mirror them diagonally over a1-h8
>, so both color mirroring and left right mirrorring.

Yes, i wrongly implied, if color mirroring is ok and left-right mirroring is ok,
combining both is ok too. But of course, it depends on the implementation.

>
>Will it still find the solutions?
>
>I bet several positions it won't :)
>
>In all those positions there has already been castled, so no such problems.
>
>I'm talking about king safety patterns which are there for g,h file but not a,b
>file.

You got me. Since my vertical color mirroring is perfectly ok (i'll hope), i
currently have exactly those asymmetries you mentioned with king- and queen
wings ;-)

Not that i'm worried about that so much, since there are only slight differences
- anyway left-right symmetry is better to fix bugs and of course small eval
differences result in totally different search trees and behaviour.

Thanks for pointing that out!

Even more strange, since i already had implemented that mirroring feature with
the intention to check left-right mirrored endgame positions. But no kingsafety
issues which i always considered asymmetric for some reasons...

Gerd



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