The New Sudoku Players' Forum

[civ623]

239 29 8| 16 369 5| 136 4 7|
39 7 15| 8 369 4| 2 56 139|
4 6 15| 12 7 239| 135 8 139|

6 13 2 | 4 8 39| 7 19 5 |
59 59 4| 67 1 67 | 38 2 38|
8 13 7 | 25 359 239 | 4 19 6 |

15 8 6| 157 4 17 | 9 3 2|
125 245 9|3 256 8| 156 7 14|
7 245 3| 9 256 16|1568 56 148|

[re'born]

Code: Select all

.------------------.------------------.------------------.
| 239   29    8    | 16    369   5    | 136-  4     7    |
| 39    7     15   | 8     369*  4    | 2     56*   139  |
| 4     6     15   | 12    7     239  | 135   8     139  |
:------------------+------------------+------------------:
| 6     13    2    | 4     8     39   | 7     19    5    |
| 59    59    4    | 67    1     67   | 38    2     38   |
| 8     13    7    | 25    359   239  | 4     19    6    |
:------------------+------------------+------------------:
| 15    8     6    | 157   4     17   | 9     3     2    |
| 125   245   9    | 3     256*  8    | 156*  7     14   |
| 7     245   3    | 9     256   16   | 1568  56-   148  |
'------------------'------------------'------------------'

One possible next move is a turbot fish or more specifically, a skyscraper, on the digit 6 that eliminates 6 from r1c7 and r9c8. From here, it is all singles.

An alternative way to make the same elimination is with an empty rectangle. Or, a finned x-wing will eliminate 6 from r2c5.

[civ623]

Ok - I am new to those two methods - can you be more specific. I have tried to figure those two out but am having trouble. I have not hear of the skyscraper at all. Thanks alot.

[re'born]

Ok - I am new to those two methods - can you be more specific. I have tried to figure those two out but am having trouble. I have not hear of the skyscraper at all. Thanks alot.

The link I gave you should be better at describing it than I can. As for the other two:
the empty rectangle is:

Code: Select all

.------------------.------------------.------------------.
| 239   29    8    | 16    369   5    | 136   4     7    |
| 39    7     15   | 8     369*  4    | 2     56*   139  |
| 4     6     15   | 12    7     239  | 135   8     139  |
:------------------+------------------+------------------:
| 6     13    2    | 4     8     39   | 7     19    5    |
| 59    59    4    | 67    1     67   | 38    2     38   |
| 8     13    7    | 25    359   239  | 4     19    6    |
:------------------+------------------+------------------:
| 15    8     6    | 157   4     17   | 9     3     2    |
| 125   245   9    | 3     256*  8    | 156   7     14   |
| 7     245   3    | 9     256*  16*  | 1568  56-   148  |
'------------------'------------------'------------------'

I lied before when I said it makes the same eliminations as the skyscraper. Strictly speaking it only eliminates 6 from r9c8 (although one could turn the technique around to also eliminate 6 from r2c5).
The finned x-wing is here:

Code: Select all

.------------------.------------------.------------------.
| 239   29    8    | 16&   369*  5    | 136*  4     7    |
| 39    7     15   | 8     369-  4    | 2     56    139  |
| 4     6     15   | 12    7     239  | 135   8     139  |
:------------------+------------------+------------------:
| 6     13    2    | 4     8     39   | 7     19    5    |
| 59    59    4    | 67    1     67   | 38    2     38   |
| 8     13    7    | 25    359   239  | 4     19    6    |
:------------------+------------------+------------------:
| 15    8     6    | 157   4     17   | 9     3     2    |
| 125   245   9    | 3     256*  8    | 156*  7     14   |
| 7     245   3    | 9     256   16   | 1568  56    148  |
'------------------'------------------'------------------'

where r1c4 is the so-called fin of the x-wing.

As with the skyscraper, I defer to better descriptions than I can provide (just see the links above).

[daj95376]

Since you are unfamiliar with the techniques presented by re'born, let's just examine the candidates for <6>. Either

Code: Select all

A) [r2c8]=6,   -or-
B) [r1c7],[r2c5],[r9c8]=6


If (B) is assumed true, then [r2c5],[r9c8]=6 eliminate all 6s in [b8]. This isn't acceptable! That leaves (A) [r2c8]=6, and the puzzle solves easily afterwards.

Code: Select all

*-----------------------------------*
|  .  .  .  |  6  6  .  | B6  .  .  |
|  .  .  .  |  . B6  .  |  . A6  .  |
|  .  6  .  |  .  .  .  |  .  .  .  |
|-----------+-----------+-----------|
|  6  .  .  |  .  .  .  |  .  .  .  |
|  .  .  .  |  6  .  6  |  .  .  .  |
|  .  .  .  |  .  .  .  |  .  .  6  |
|-----------+-----------+-----------|
|  .  .  6  |  .  .  .  |  .  .  .  |
|  .  .  .  |  .  6  .  |  6  .  .  |
|  .  .  .  |  .  6  6  |  6 B6  .  |
*-----------------------------------*


Note to purists: He said try not technique.

[civ623]

Ok thanks I am going to try to do this. THanks for your help.

[re'born]

Note to purists: He said try not technique.

Well , of course he said try. It wouldn't have made sense if he'd written, "Can someone tell me what to technique next on this puzzle"

Seriously, nice explanation daj.