Author: Les Fernandez
Date: 20:17:53 02/08/03
As we all know, generating egtb's for the 6 piece sets require alot of time and
computer hardware to do. I have an idea that appears to reduce the amount of
work needed to generate these permutations and would like to hear follow-up on
your thoughts. What I propose to do is explained in the following example.
Suppose we are in the process of generating the 6 piece EGTB for kbrnkr and for
the sake of this example lets assume we are working with the following position:
3k3r/8/2K5/3BRN2/8/8/8/8 w - -
SOLUTION according to Crafty = acd 9; acn 1910070; acs 7; ce 32758; pv Bf7 Kc8
Rb5 Rh7 Be6+ Rd7 Bxd7+ Kd8 Rb8#;
Obviously this is just one position out of who knows how many positions for this
1 egtb. Now based on the above analysis we see the key move (target square) is
Bf7. Now if we take that target square (f7) does anyone see any reason we can't
put a black p,n,b,r or q on it?? If we can legally do that then would we not be
generating the solution for 5 new positions that are actually now the solutions
for 5 positions for the 7 piece egtb??. Look at the following diagrams:
[D]3k3r/5p2/2K5/3BRN2/8/8/8/8 w - -
[D]3k3r/5n2/2K5/3BRN2/8/8/8/8 w - -
[D]3k3r/5b2/2K5/3BRN2/8/8/8/8 w - -
[D]3k3r/5r2/2K5/3BRN2/8/8/8/8 w - -
[D]3k3r/5q2/2K5/3BRN2/8/8/8/8 w - -
Does it make any difference what is on or not on the target square?? Regarding
this method it appears that there are only a few rules that need to be defined
unless you guys can come up with others. Following are the apparent rules that
I see:
Substitutions are done according to the following all substitutions are based on
the color of the opposing side and secondly pawn substitutions can not be made
if the target square is on row 1 and it is black to move (since white pawn can't
exist on row 1) and conversly pawn substitution is not allowed on row 8 if it is
white to move (since a black pawn can't exist on row 8.):
If target square is blank then we substitute:
pawn
knight
bishop
rook
queen
If target square has a pawn on it then we substitute:
blank
knight
bishop
rook
queen
If target square has a knight on it then we substitute:
blank
pawn
bishop
rook
queen
If target square has a bishop on it then we substitute:
blank
pawn
knight
rook
queen
If target square has a rook on it then we substitute:
blank
pawn
knight
bishop
queen
If target square has a queen on it then we substitute:
blank
pawn
knight
bishop
rook
All of these appear to me to be legally sound and will provide us with 5 new
solutions for the 7 piece EGTB for every 6 piece EGTB position that is
generated. If we take it one step further we can also say that we can permutate
each position 4 ways based on symmetry which then would provide us with 20 new
positions for the n+1 EGTB set as we generate the positions for the 6 piece
EGTB.
Please give some serious thought to this idea since it may allow us to generate
EGTB's much more quickly. I will look forward to hearing your thoughts.
Thanks,
Les
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