- Code: Select all
`a b`

b a

where the digits are on the corners of a rectangle with one ab-pair in one 3x3 box and the other ab-pair in another 3x3 box? I.e., every digit in the solution is one of four digits in such a pattern. The closest I've found so far is the solution to the following puzzle (where I've used just the four-digit patterns themselves as clues):

- Code: Select all
`. 2 1 | 7 4 8 | 6 3 .`

5 8 6 | 9 3 2 | 1 4 7

4 7 3 | . . 1 | 2 . .

------+-------+------

8 . 2 | . . . | . 7 4

3 1 4 | 8 . 7 | . . 2

. 5 9 | . . . | . . .

------+-------+------

6 9 5 | . 8 4 | 7 . 1

2 4 8 | 1 . 5 | 3 9 .

1 3 7 | 2 . 9 | 4 5 .