Author: Tom Likens
Date: 13:18:29 02/27/04
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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. > >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. Hello Vincent, I saw *exactly* these type of problems when I implemented the left-right and top-bottom mirroring functions to test my evaluation function. Some of the bugs I ran across were the inconsistent scoring of the D-pawn isolani, keeping the F-pawn (instead of the C-pawn) unblocked if we had castled queenside etc. All of these showed up when I mirrored left to right, (mirroring top to bottom things were more consistent). And as you mentioned king safety issues also stood out. It was rather eye-opening (and a bit humbling) actually. It's amazing how easy it is to have a "I'm playing white" bias when creating evaluation terms and scoring routines. regards, --tom
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