The New Sudoku Players' Forum

[Kent]

Code: Select all

 4 6 . | . . 7 | 1 . 9
 9 1 . | 6 5 4 | . 7 3
 7 . 3 | . 9 1 | 4 . 6
-------+-------+------
 . 4 1 | 9 . 5 | 7 6 .
 . 7 6 | 1 8 . | 9 4 5
 . 9 . | 4 7 6 | 3 . 1
-------+-------+------
 1 . 9 | 7 6 . | 5 3 4
 . 3 7 | . 4 9 | 6 1 .
 6 . 4 | . 1 . | . 9 7


 4   6   258 | 238 23  7   | 1   258 9 
 9   1   28  | 6   5   4   | 28  7   3 
 7   258 3   | 28  9   1   | 4   258 6 
-------------+-------------+-------------
 238 4   1   | 9   23  5   | 7   6   28
 23  7   6   | 1   8   23  | 9   4   5 
 258 9   258 | 4   7   6   | 3   28  1 
-------------+-------------+-------------
 1   28  9   | 7   6   28  | 5   3   4 
 258 3   7   | 25  4   9   | 6   1   28
 6   258 4   | 235 1   238 | 28  9   7 


Any suggestion on how to procede??

[ronk]

Any suggestion on how to proceed??

There is an x-wing in r48c19. The 8s in rows 4 and 8 can only be placed in cols 1 and 9. Therefore, no 8s can be placed anywhere else in those cols.

After that, coloring a single conjugate chain of 2s yields another elimination.

[Sped]

remote pairs on 28:

(r2c3)-(r2c7)-(r9c7)-(r8c9)-(r4c9)-(r6c8)

eliminates the 2 and the 8 in r6c3

It's all singles from there.

[TKiel]

In box 8, box-line interaction removes candidate 8's from column 4, which opens things up for colouring on 8. One more step than Sped's method but solves it just the same.

Tracy

[emm]

You don't often get a puzzle like this where you can colour 2 numbers - 2 and 8 - simultaneously.

[Sped]

You don't often get a puzzle like this where you can colour 2 numbers - 2 and 8 - simultaneously.

In this example I first spotted it as an XY chain, since I like to look for those. Then I realized it worked both ways.. with 2s on the ends and with 8s on the ends.

Remote pairs!