The New Sudoku Players' Forum

[Icebreaker43]

Hi there this will be my first post. I have been doing Sudoku for several years now, mainly using Simple Sudoku by Angus Johnson. So i believe that I am comfortable with the techniques used in that program. I had this puzzle recently:

Code: Select all

*-----------*
 |9.3|.2.|..4|
 |.7.|8..|3..|
 |12.|..3|6..|
 |---+---+---|
 |...|2..|7.5|
 |7..|...|..8|
 |5.2|..6|...|
 |---+---+---|
 |..1|4..|.56|
 |..9|..2|.7.|
 |6..|.5.|9.2|
 *-----------*

Which I solved to this

Code: Select all

*-----------*
 |9.3|.27|5.4|
 |47.|8..|32.|
 |12.|.43|6.7|
 |---+---+---|
 |3..|2..|7.5|
 |7..|...|2.8|
 |5.2|7.6|14.|
 |---+---+---|
 |231|479|856|
 |859|..2|47.|
 |647|.58|9.2|
 *-----------*

 
 *-----------------------------------------------------------*
 | 9     68    3     | 16    2     7     | 5     18    4     |
 | 4     7     56    | 8     169   15    | 3     2     19    |
 | 1     2     58    | 59    4     3     | 6     89    7     |
 |-------------------+-------------------+-------------------|
 | 3     1689  468   | 2     189   14    | 7     69    5     |
 | 7     169   46    | 359   139   145   | 2     369   8     |
 | 5     89    2     | 7     389   6     | 1     4     39    |
 |-------------------+-------------------+-------------------|
 | 2     3     1     | 4     7     9     | 8     5     6     |
 | 8     5     9     | 36    136   2     | 4     7     13    |
 | 6     4     7     | 13    5     8     | 9     13    2     |
 *-----------------------------------------------------------*

I did some coloring for threes (r6c59 r59c8 r8c9 & r9c4) That left r5c45 & r8C45 uncolored. I thought (just for fun ) I would see if this would work as a "hidden x-wing". To my surprise it did
I have tried it on several puzzles since then and it has worked every time ( even worked on a "hidden swordfish") so long as none of the candidates in the "x-wing" can be colored in another chain.
**EDIT** I eliminated three from r6c5, r9c4, r8c9 & r5c8 Making r6c9 & r9c8=3
What is this technique or have I just been lucky

P.S. Forgive me if my terminology is not accurate, as I said this is my first posting in a Sudoku forum

[ronk]

Code: Select all

 *-----------------------------------------------------------*
 | 9     68    3     | 16    2     7     | 5     18    4     |
 | 4     7     56    | 8     169   15    | 3     2     19    |
 | 1     2     58    | 59    4     3     | 6     89    7     |
 |-------------------+-------------------+-------------------|
 | 3     1689  468   | 2     189   14    | 7     69    5     |
 | 7     169   46    |*359  *139   145   | 2     369   8     |
 | 5     89    2     | 7     389   6     | 1     4     39    |
 |-------------------+-------------------+-------------------|
 | 2     3     1     | 4     7     9     | 8     5     6     |
 | 8     5     9     |*36   *136   2     | 4     7     13    |
 | 6     4     7     | 13    5     8     | 9     13    2     |
 *-----------------------------------------------------------*

I did some coloring for threes (r6c59 r59c8 r8c9 & r9c4) That left r5c45 & r8C45 uncolored. I thought (just for fun ) I would see if this would work as a "hidden x-wing". To my surprise it did
I have tried it on several puzzles since then and it has worked every time ( even worked on a "hidden swordfish") so long as none of the candidates in the "x-wing" can be colored in another chain.
**EDIT** I eliminated three from r6c5, r9c4, r8c9 & r5c8 Making r6c9 & r9c8=3
What is this technique or have I just been lucky

Hi icebreaker43, welcome to this forum ... and congrats on the appearance of your grids. First time posters ususally don't do that well.

As to your "technique", I'm sorry to say you've just been lucky. It's basically a guess that the "hidden x-wing", presumably 3r58c45 as I marked above, will ultimately be true. You will eventually run across instances where that's not the case.