The New Sudoku Players' Forum

[bradles]

I am using Simple Sudoku to teach myself as many of the different techniques for solving as I can learn.
I have had great success just using the generated puzzles from the program, however tried using it with a grid rated "tough" at http://www.sudoku.com.au/1V15-2-2006-sudoku.aspx to see how I go with a really tough puzzle.

I got so far through this puzzle and it said "no hint available". I am wondering if I have to do some trial and error to further progress through this puzzle. Is there any techniques for this? (Forced chains?)

Brad

[Carcul]

Hi Bradles.

You will never need Trial and Error to proceed, you just need to learn some advanced techniques like forcing chains (nice loops), Almost Locked Sets, Uniqueness. For example, check here for a good thread about nice loops.

Regards, Carcul

[ravel]

Uff, this puzzle is really tough, guess it is something for the monster chain experts here.
This is a copy:

Code: Select all

------------
8..|7..|.1.
..4|..9|...
2..|.3.|8..
------------
.3.|...|..9
...|416|...
5..|...|.4.
------------
..8|.2.|..7
...|9..|5..
.2.|..5|..3
------------


My program tells me, it can be solved by showing that R8C9=2 leads to a contradiction (=> R8C8=2), but i do not want to bother you with the long output ...

[tarek]

Uff, this puzzle is really tough, guess it is something for the monster chain experts here.

Code: Select all

------------
8..|7..|.1.
..4|..9|...
2..|.3.|8..
------------
.3.|...|..9
...|416|...
5..|...|.4.
------------
..8|.2.|..7
...|9..|5..
.2.|..5|..3
------------


Hi ravel,

My solver needed only one simple guess not targeting a magic cell to crack it.

however it had this XYZ wing:

Code: Select all

*--------------------------------------------------------*
| 8    *69    3569 | 7     46    24   | 2369  1     25   |
| 37    1     4    | 2568  58    9    | 267   35    256  |
| 2    -679  *569  |*56    3     1    | 8     679   4    |
|------------------+------------------+------------------|
| 4     3     126  | 58    578   278  | 1267  67    9    |
| 79    789   279  | 4     1     6    | 23    35    258  |
| 5     68    126  | 23    9     237  | 1267  4     268  |
|------------------+------------------+------------------|
| 19    5     8    | 13    2     34   | 469   69    7    |
| 367   4     37   | 9     678   78   | 5     2     1    |
| 1679  2     79   | 16    467   5    | 49    8     3    |
*--------------------------------------------------------*

This finned Swordfish:

Code: Select all

*-----------------------------------------------------------------*
| 8      69     3569  | 7      456    24    | 2369   1      2456  |
| 1367   167    4     |*12568 *568    9     | 2367   23567  256   |
| 2      1679   15679 | 156    3      14    | 8      5679   456   |
|---------------------+---------------------+---------------------|
| 4      3      1267  |*258   *578   %278   | 1267  *2678   9     |
| 79     789    279   | 4      1      6     | 237    23578  258   |
| 5      1678   1267  |-238    9      2378  | 1267   4      1268  |
|---------------------+---------------------+---------------------|
| 1369   5      8     | 136    2      134   | 1469   69     7     |
| 1367   4      1367  | 9      678    1378  | 5      268    1268  |
| 1679   2      1679  |*168   *4678   5     | 1469  *689    3     |
*-----------------------------------------------------------------*

and this beautiful CLASSIC WXYZ wing was there:

Code: Select all

*--------------------------------------------------------*
| 8     69    3569 | 7     46    24   | 2369  1     256  |
| 1367  167   4    | 2568  568   9    | 2367  3567  256  |
| 2     679   5679 | 56    3     1    | 8     5679  4    |
|------------------+------------------+------------------|
| 4     3     1267 | 58    578   278  | 1267  67    9    |
|*79    789   279  | 4     1     6    | 237   357   258  |
| 5     1678  1267 | 23    9     237  | 1267  4     268  |
|------------------+------------------+------------------|
|*19    5     8    | 13    2     34   | 469   69    7    |
| 367   4     367  | 9     678   78   | 5     2     1    |
|*1679  2    -1679 |^16    467   5    | 49    8     3    |
*--------------------------------------------------------*

Tarek

[ravel]

Oops, when i checked it again now, i saw that my solver did *not* solve the puzzle with the 2 in R8C8 without guessing, sorry. So it is even harder than i thought.
A second step could be to show that R1C3<>3. Then R2C1=3, which solves it finally.

[yasmin]

Hi guys

I wonder if there's any way to post your examples so that the final columns don't appear (visually) as overlapping the first ones. I find it difficult to follow your examples because of this. Thanks in advance....

[vidarino]

Hi guys

I wonder if there's any way to post your examples so that the final columns don't appear (visually) as overlapping the first ones. I find it difficult to follow your examples because of this. Thanks in advance....

They all look fine here. Try reducing your font size. Or zooming out a bit, if your browser supports that.

Vidar

[ronk]

They all look fine here. Try reducing your font size.

This web site somehow has destroyed the option to do that ... at least with IE6. That's very user unfriendly IMO.

Ron