Does this pattern have a name?

gjz44 · Posted: Sun Feb 26, 2006 11:37 pm Post subject: Does this pattern have a name?

Hi,

I am relatively new to sudoku, but I just figured out a pattern and wondered if others had found it. It is related to associated pairs. Say I have two ajacent squares:

0 89* 9* | 0 89 0
0 0 0 | 0 0 0
0 89* 0 | 0 89 0

89* = square that 8 or 9 can be in plus maybe others
89 = square that only 8 or 9 can be in
9* = square that 9 and others can be in

0= square that other numbers besides 8 or 9 can be in.

Therefore, this must be reducable to:
0 8* 9* | 0 89 0
0 0 0 | 0 0 0
0 89* 0 | 0 89 0

(top 89* can't be a 9)

Why? If it were a 9, then the two squares would be:

0 89 0 | 0 89 0
0 0 0 | 0 0 0
0 89 0 | 0 89 0

This means that the puzzle would be unsolvable, because no other row or column could have an 89 in the rows and columns above where 89 were present. Therefore, there would be no way to determine that those 89s were either an 8 or a 9.

Thanks,
Gabe

Ruud · Site Admin

Try to search this forum for "uniqueness"
You can also find uniqueness test in the solving techniques index

Ruud.
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