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Does anyone knows how i can print the sudoku with the
pencil marks?

hi all,

What was the intuition to chose those cells & digits:
r1c5 or r3c6 = 6
r4c4<>4

how did you spot that?

does anyone has a simpler solution to this one?

As far as i know it should be a closed shape, c9r1 steps out.

The puzzle is from book called "absolutely nasty sudoku - level 4"

dan hi,

saw your remark, it doesn't help solving

+---------------+----------------+--------------+
| 3 9 4 | 2 568 7 | 568 1 568 |
| 56 8 1 | 9 3456 3456 | 56 7 2 |
| 567 567 2 | 168 1568 56 | 4 3 9 ...

thanks all!

really learned a lot !

After the X wing (and a possibly useless XYZ wing removing the 4 from r5c1)
Hugh, it's far from useless.

on what cells do you do this XYZ wing

This is the grid with c1 taken further.

+---------------+-------------+------------+
| 35 2 459 | 6 1 49 | 34 8 7 |
| 7 3469 4689 | 48 24 5 | 234 1 269 |
| 468 1 4689 | ...

You missed a basic move in column 1, and then you'll still need a couple of advanced moves.

+--------------------------------------------------------------+
| 345 2 459 | 6 1 4 ...

+---------------+-------------+------------+
| 345 2 459 | 6 1 49 | 34 8 7 |
| 7 3469 4689 | 48 24 5 | 234 1 269 |
| 468 1 4689 | 3 7 2489 | 5 49 269 |
+--------------- ...