Author: KarinsDad
Date: 08:46:33 05/29/99
Go up one level in this thread
On May 28, 1999 at 16:24:26, Dann Corbit wrote: >Transparent pawns: >4k3/8/8/PPPPPPPP/pppppppp/8/8/4K3 w - - Well, the set of calculations that Uri used to illustrate more than 100 bits in the other thread would not see this position since the algorithm assumes all 32 pieces on the board (and hence, all pawns go white/black). So, this position would not be considered legal (and it isn't). > >You can't get there from here: >4k3/Pp6/Pp6/Pp6/Pp6/Pp6/Pp6/4K3 w - - >rnbqkbnr/pppppppp/8/8/4B3/8/PPPPPPPP/RNBQK1NR w KQkq - This illegal position was not taken into account via the calculations, but it was mentioned that there would be positions like this (where neither pawn is pushed) that would be in the calculation and still be illegal. > >Simultaneous check: >rnbqk1nr/ppppp2p/5ppb/8/8/5PPB/PPPPP2P/RNBQK1NR w KQkq - This one is taken into account (I assume you wanted the 2 bishops switched). There must be 32 pieces and they must be the proper pieces and they must be on the proper color. > >Illegal approach: >8/8/8/3Kk3/8/8/8/8 w - - This one also was not taken into account. > >Parity Error: >rn1qk1nr/ppp2ppp/1b6/2bpp3/3PP3/3BB3/PPP2PPP/RN1QK1NR w KQkq - And, not taken into account. > > >What other categories are there? There is also the category that the side to move is in check more than twice. There is also the category that the side to move is in check twice, but both of them are knights. There are probably a few more. The largest category (which increases the size of the calculations illegally) is that the side not to move is in check (a superset of the simultaneous check that you have above). This is due to the fact that in a great majority of positions (32 pieces on the board), the side to move has (on average) 40 or so of the squares attacked by at least one piece. I think you can throw ALL of the other categories into a huge pot and you would not even drop the calculations by 1 bit. But, this category will probably drop it by several bits. KarinsDad :)
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