Author: Gerd Isenberg
Date: 12:53:15 02/26/04
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On February 26, 2004 at 15:13:16, Gerd Isenberg wrote: >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. Sharing source code for left-right mirrored files and patterns is another issue. I like the idea of using C++ template int(kingwing|queenwing)-parameter with two function incarnations, rather than using an actual parameter with one single function. > >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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