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Normal Topic Not all 5-piece positions are in SyZyGy (Read 1199 times)
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Re: Not all 5-piece positions are in SyZyGy
Reply #1 - 04/25/16 at 14:03:45
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On my Mac Book Retina under Scid vs Mac I see no difference between these two FEN strings in dealing by Komodo and Stockfish using the SyZyGy
  
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GeneM
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Not all 5-piece positions are in SyZyGy
03/26/16 at 23:06:35
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A minor observation that the Endgame Tablebases which advertise as having "all 5-piece" positions are a lying a little bit.
Here, as FEN, is a 5-piece position the SyZyGy Endgame Tablebases lack:

r3k3/8/4PK2/8/8/8/1R6/8 b q - 0 1

The crucial element in the preceding FEN is the 'q' which means Black can castle ooo (ke8-c8) if he likes.
For SyZyGy to include the position, the 'q' must be replaced with a '-', as in:

r3k3/8/4PK2/8/8/8/1R6/8 b - - 0 1

I have always felt the 50 move rule should include "No change in castling eligibility", along with "No pawn moves" etc.
I suppose the argument is over what the best definition of 'position' should be.
.
  

GeneM , CastleLong.com , FRC-chess960
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