The New Sudoku Players' Forum

[Fonzarelle]

I've tried all the strategies I've recently learned and am stuck here. Any strategy anyone can advise me to look into for myself?


https://pasteboard.co/pQkvvttKAxXu.png

[marek stefanik]

Hi Fonzarelle,

You can eliminate 4r9c2 with a fish (for example finned x-wing in r67 or two-string kite in r6c9.
Moving past this point, the puzzle gets very difficult and is not solvable with basic AICs.
This step should get you through that:

Code: Select all

.-------------------.--------------------.----------------.
| 4     8    236    | 269    1      269  | 39   5    7    |
| 3679  1    367    | 4      5      679  | 8    2    369  |
| 679   5    267    | 2689   26789  3    | 4    1    69   |
:-------------------+--------------------+----------------:
| 567   3    9      | 256    4      256  | 57   8    1    |
| 1567  2    14567  | 13569  369    8    | 39   67–4 3459 |
| 158  d46   158    | 7      39     159  | 2   c46   359  |
:-------------------+--------------------+----------------:
| 1358 e479  13458  | 13589  3789   1579 | 6   b47   2    |
|a156  e679 a156    | 269–15 2679   4    |a157  3    8    |
| 2    e67   13458–6| 13568  3678   1567 | 15–7 9    45   |
'-------------------'--------------------'----------------'

(6=157)r8c137 – (7=4)r7c8 – 4r6c8 = (4–6)r6c2 = 6r789c2 – Loop => –15r8c4, –7r9c7, –4r5c8, –6r9c3

Then you can solve the puzzle with basic AICs (longest chains in my path were of length 4).
I'll add the rest of my path so that you can have a look if you get stuck. I won't add a diagram to each step, so if anything is unclear, just ask.

The rest of my path: Show

S-Wing: 7r4c1 = 7r4c7 – (7=6)r5c8 – 6r6c8 = 6r6c2 => –6r4c1
H3-Wing:(7=6)r5c8 – (6=4)r6c8 – 4r6c2 = 4r5c3 => –7r5c3
W-Wing with transfer: (7=6)r9c2 – 6r6c2 = 6r6c8 – (6=7)r5c8 – 7r7c8 = 7r8c7 => –7r8c2
HP 26r4c46, NP 39r56c5 (there are more basic steps available, but you don't really need them)
Almost-Locked Triple: 78r7c5 and 47r7c8 have to go somewhere in b7 => 7r9c2, 48r9c3, no more 478 in r7 outside b7 (-8r7c4, -7r7c6), stte

Marek

[Vorlauf]

After marek stefanik's steps, there is a "bent quad" of digits 1567 :

Code: Select all

.-------------------.--------------------.----------------.
| 4     8    236    | 269    1      269  | 39   5    7    |
| 3679  1    367    | 4      5      679  | 8    2    369  |
| 679   5    267    | 2689   26789  3    | 4    1    69   |
:-------------------+--------------------+----------------:
| 567   3    9      | 256    4      256  | 57   8    1    |
| 1567  2    14567  | 13569  369    8    | 39   67   3459 |
| 158  d46   158    | 7      39     159  | 2    46   359  |
:-------------------+--------------------+----------------:
| 1358  479  13458  | 13589  3789   1579 | 6    47   2    |
 a156  69-7 a156    | 269    2679   4    |a157  3    8    |
| 2    a67   13458  | 13568  3678   1567 | 15   9    45   |
'-------------------'--------------------'----------------'

candidates 1,5,6 are restricted. Candidate 7 is the unrestricted , so candidate 7 in r8c2 may be eliminated.

[Fonzarelle]

Thanks for your help! This puzzle is probably a bit to advanced for me.