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Subject: Re: number of pawn positions in chess...

Author: Michael Neish

Date: 02:02:48 01/14/00

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>For doubled White A-Pawns, Black can have Doubled Pawns on files
>A to F, and in addition, for files B-G the file to the left or
>right of the doubled Pawns can be empty.
>
>For the case of doubled White A-Pawns, we get
>
>White Doubled A, Black Doubled A = 1.025e9
>White Doubled A, Black Doubled B, no B-Pawn on A-file = 2.567e9
>White Doubled A, Black Doubled B, no B-Pawn on C-file = 4.101e9
>White Doubled A, Black Doubled C, no B-Pawn on B-file = 2.734e9
>White Doubled A, Black Doubled C, no B-Pawn on D-file = 6.561e9
>White Doubled A, Black Doubled D, no B-Pawn on C-file = 6.561e9
>White Doubled A, Black Doubled D, no B-Pawn on E-file = 6.561e9
>White Doubled A, Black Doubled E, no B-Pawn on D-file = 6.561e9
>White Doubled A, Black Doubled E, no B-Pawn on F-file = 6.561e9
>White Doubled A, Black Doubled F, no B-Pawn on E-file = 6.561e9
>White Doubled A, Black Doubled F, no B-Pawn on G-file = 6.561e9
>White Doubled A, Black Doubled G, no B-Pawn on F-file = 6.561e9
>White Doubled A, Black Doubled G, no B-Pawn on H-file = 6.561e9
>White Doubled A, Black Doubled H, no B-Pawn on G-file = 6.561e9
>
>Which comes to 7.5012e10.
>

This calculation allows Black Pawns to be behind White Pawns
on the doubled Pawn files.  Maybe I should think before
posting.  If you don't allow any Black Pawns behind White
Pawns, it becomes:

File containing W and B doubled Pawns = 15 combinations.
File containing one set of doubled Pawns and one Pawn of
opposing colour = 20 combinations
File containing one set of doubled Pawns and no opposing
Pawns = 15 combinations
File containing one W and one B undoubled Pawn = 15 combinations
File containing only one Pawn = 6 combinations
File containing no Pawns = 1 combination

Based on this, we get.

White Doubled A, Black Doubled A = 15x1x15^6 = 1.709e9
White Doubled A, Black Doubled B, no B Pawn on A-file = 15x15x15^6 = 2.563e9
White Doubled A, Black Doubled B, no B Pawn on C-file = 20x15x6x15^5 = 1.367e9
White Doubled A, Black Doubled C, no B Pawn on B-file = 20x1x20x15^5 = 3.038e8
White Doubled A, Black Doubled C, no B Pawn on D-file = 20x6x20x6x15^4 = 7.29e8
White Doubled A, Black Doubled D, no B Pawn on C-file = 20x6x6x20x15^4 = 7.29e8
White Doubled A, Black Doubled D, no B Pawn on E-file = 20x6x15x20x6x15^3 =
7.29e8
White Doubled A, Black Doubled E, no B Pawn on D-file = 7.29e8
White Doubled A, Black Doubled E, no B Pawn on F-file = 7.29e8
White Doubled A, Black Doubled F, no B Pawn on E-file = 7.29e8
White Doubled A, Black Doubled F, no B Pawn on G-file = 7.29e8
White Doubled A, Black Doubled G, no B Pawn on F-file = 7.29e8
White Doubled A, Black Doubled G, no B Pawn on H-file = 7.29e8
White Doubled A, Black Doubled H, no B Pawn on G-file = 7.29e8

Which comes to 1.213e10.

Maybe we should rename this thread "see how many different answers
we can get for the same thing".

Mike.





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