The New Sudoku Players' Forum

[iRob]

Here's my progress so far...

Puzzle: SudokuHints.com wicked 10-24-05

Code: Select all

+-------+-------+-------+
| . . 4 | . . . | . 7 . |
| 6 9 . | 2 . 3 | 4 1 5 |
| . 5 2 | . . . | . 6 8 |
+-------+-------+-------+
| . 2 . | . 3 . | . 9 . |
| . 4 . | 1 . 8 | . . 3 |
| . 3 . | . 6 . | . 8 . |
+-------+-------+-------+
| 2 . . | . . . | . 4 . |
| . 6 5 | 7 . 4 | . 3 1 |
| 4 7 . | . . . | 8 . . |
+-------+-------+-------+

+-------------------+-------------------+-------------------+
| 138   18    4     | 5689  1589  1569  | 239   7     29    |
| 6     9     78    | 2     78    3     | 4     1     5     |
| 137   5     2     | 49    1479  179   | 39    6     8     |
+-------------------+-------------------+-------------------+
| 1578  2     1678  | 45    3     57    | 1567  9     467   |
| 579   4     679   | 1     2579  8     | 567   25    3     |
| 1579  3     179   | 459   6     2579  | 157   8     247   |
+-------------------+-------------------+-------------------+
| 2     18    1389  | 35689 1589  1569  | 567   4     679   |
| 89    6     5     | 7     289   4     | 29    3     1     |
| 4     7     139   | 3569  1259  12569 | 8     25    269   |
+-------------------+-------------------+-------------------+


[Nick67]

Hi iRob,

I found an X-Wing of 4's, marked below. (Took me a while! )

Code: Select all

+-------------------+-------------------+-------------------+
| 138   18    4     | 5689  1589  1569  | 239   7     29    |
| 6     9     78    | 2     78    3     | 4     1     5     |
| 137   5     2     | 49    1479  179   | 39    6     8     |
+-------------------+-------------------+-------------------+
| 1578  2     1678  | 45*   3     57    | 1567  9     467*  |
| 579   4     679   | 1     2579  8     | 567   25    3     |
| 1579  3     179   | 459*  6     2579  | 157   8     247*  |
+-------------------+-------------------+-------------------+
| 2     18    1389  | 35689 1589  1569  | 567   4     679   |
| 89    6     5     | 7     289   4     | 29    3     1     |
| 4     7     139   | 3569  1259  12569 | 8     25    269   |
+-------------------+-------------------+-------------------+


[Nick67]

I found an X-Wing of 4's, marked below. (Took me a while! )

Oh, wait, there's also a hidden single in c5.
Not feeling so good about my X-Wing anymore!

[iRob]

X-wings. Star Wars, right? ;-) Yeah, so you've forced me to progress my sudoku education. I referred to this site: http://www.angusj.com/sudoku/hints.php

I think I understand. However, using Sudoku Susser on that puzzle, it reports that "there are no useful XY-wing patterns". Are XY different than X?

Even with your X-wing pattern of 4s, there are no other candidates that can be removed. Am I missing something?

[Ruud]

Not feeling so good about my X-Wing anymore

This little wicked thing can be solved with only 1 naked pair. The rest is singles only.

Are XY different than X?

Yes, they are 2 different things. First of all, XY-wings are not known in Star Wars...

X-Wings are explained here: http://www.simes.clara.co.uk/programs/sudokutechnique6.htm
XY-Wings are explained here: http://www.simes.clara.co.uk/programs/sudokutechnique11.htm

Ruud.

[CathyW]

Even with your X-wing pattern of 4s, there are no other candidates that can be removed. Am I missing something?

Notwithstanding the easier methods of solving the puzzle - the X-wing of 4s does allow elimination of other 4s in column 4, thus giving 9 in r3c4. Does that make you feel better Nick?!

[Nick67]

Yes, thank you Cathy! Well said, too.