The New Sudoku Players' Forum

[Josh]

Not sure if this is tricky or if I'm missing something obvious (again!) but any pointers you could give me towards techniques that might help me progress would be appreciated...

The start:

Code: Select all

..6|.83|...
.9.|.6.|...
.21|4..|6..
---+---+---
18.|...|.7.
..2|.7.|5..
.6.|...|.34
---+---+---
..3|..5|48.
...|.3.|.9.
...|82.|7..



Where I've got to:

Code: Select all

..6|.83|...
.9.|.6.|3..
321|497|658
---+---+---
185|34.|.7.
432|.78|5..
.6.|.5.|834
---+---+---
.73|.15|48.
...|73.|.95
...|82.|7.3



My candidates:

Code: Select all

57  45  6   | 125 8 3   | 19 24 179
578 9   478 | 125 6 12  | 3  24 17
3   2   1   | 4   9 7   | 6  5  8
------------+-----------+----------
1   8   5   | 3   4 69  | 29 7  269
4   6   2   | 69  7 8   | 5  16 169
79  6   79  | 12  5 12  | 8  3  4
------------+-----------+----------
269 7   3   | 69  1 5   | 4  8  26
268 14  48  | 7   3 46  | 12 9  5
569 145 49  | 8   2 469 | 7  16 3



TIA,

Cheers!

Josh.

[Carcul]

Hi Josh.

You have a Turbot Fish on cells r7c9/r7c4/r5c4/r4c6/r4c9 that eliminates the "6" from r7c9, solving the puzzle.

Regards, Carcul

[tarek]

Code: Select all

*-----------------------------------------------*
| 57   45   6   | 125  8    3   | 19   24   179 |
| 578  9    478 | 125  6    12  | 3    24   17  |
| 3    2    1   | 4    9    7   | 6    5    8   |
|---------------+---------------+---------------|
| 1    8    5   | 3    4    69  | 29   7    269 |
| 4    3    2   |*69   7    8   | 5   *16   169 |
| 79   6    79  | 12   5    12  | 8    3    4   |
|---------------+---------------+---------------|
| 269  7    3   |*69   1    5   | 4   *8   -26  |
| 268  14   48  | 7    3    46  | 12   9    5   |
| 569  145  49  | 8    2    469 | 7   #16   3   |
*-----------------------------------------------*
Eliminating 6 From r7c9 (Almost Finned XWing in Columns 4 & 8)

Solves the puzzle

[Josh]

Cool!

That's a new one - I shall mostly be reading up on Turbot Fishes...

Cheers!

Josh.

[CathyW]

The "easy" way is to use the uniqueness test on r2c4,6 and r6c4,6 which indicates that r2c4 must be 5 otherwise you'd have at least 2 solutions to the puzzle. The rest solves with singles.

[Carcul]

Hi CathyW.

The "easy" way is to use the uniqueness test on r2c4,6 and r6c4,6 which indicates that r2c4 must be 5 otherwise you'd have at least 2 solutions to the puzzle. The rest solves with singles.

I have also spoted the unique rectangle, but after using uniqueness to make r2c4=5 the rest does not solve with singles. Using directly the Turbot Fish (or other advanced technique) does lead to only singles.

Regards, Carcul

[TKiel]

Also, coloring on 6's using two conjugate chains reveals r9c8=6.

Interesting: one puzzle-- 4 people--four different solution methods.

Tracy

[CathyW]

I have also spoted the unique rectangle, but after using uniqueness to make r2c4=5 the rest does not solve with singles. Using directly the Turbot Fish (or other advanced technique) does lead to only singles.

Apologies - a few more eliminations were required before getting to the point of singles only. But after the the uniqueness making r2c4=5, the eliminations were fairly straightforward xy-chains.

[QBasicMac]

Interesting: one puzzle-- 4 people--four different solution methods.

And a fifth way (heh)

After reaching this

Code: Select all

+---------------+-------------+-------------+
| 57   45   6   | 125  8  3   | 19  24  179 |
| 578  9    478 | 125  6  12  | 3   24  17  |
| 3    2    1   | 4    9  7   | 6   5   8   |
+---------------+-------------+-------------+
| 1    8    5   | 3    4  69  | 29  7   269 |
| 4    3    2   | 69   7  8   | 5   16  169 |
| 79   6    79  | 12   5  12  | 8   3   4   |
+---------------+-------------+-------------+
| 269  7    3   | 69   1  5   | 4   8   26  |
| 268  14   48  | 7    3  46  | 12  9   5   |
| 569  145  49  | 8    2  469 | 7   16  3   |
+---------------+-------------+-------------+


note that r5c8 is 1 or 6.

Make copy of puzzle and place 1 in one copy and 6 in the other.

The copy with 6 fails.

The copy with 1 solves.

Hence the puzzle is valid and we have found the only solution.

Mac