The New Sudoku Players' Forum

[tso]

SOLO, a free applet in Simon Tatham's Portable Puzzle Collection, will create puzzles with your choice of 7 different types of symmetry:

2 way rotation
4 way rotation
2 way mirror
2 way diagonal mirror
4 way mirror
4 way diagonal mirror
8 way mirror

... in 6 levels of difficulty.


Micheal Kennett's program allows you to create any template(s) you wish, though the time it takes to find a match can vary greatly.

Here's a few I created just now with a some of my own templates:

Code: Select all

 1 2 6 . . . . . .
 3 . 4 . . . 2 1 6
 9 8 5 . . . 4 . 3
 . . . . . . 7 2 8
 . 6 7 5 . . . . .
 . 4 . 9 . . . . .
 . 1 9 2 . 6 3 4 .
 . . . . . 9 . 8 .
 . . . . . 3 6 9 .



 4 7 6 . . . . . .
 1 . 8 . . 7 5 6 .
 5 2 3 . . 8 . 7 .
 . . . . . 9 7 8 .
 . 6 1 5 . . . . .
 . 4 . 1 . . . . .
 . 3 5 8 . . 4 2 6
 . . . . . . 9 . 3
 . . . . . . 8 5 7



 9 6 4 . . . . . .
 1 . 2 . . . . . .
 5 7 8 . . 3 2 4 .
 . . . . . 8 . 7 .
 . 4 9 5 . 2 1 8 .
 . 5 . 7 . . . . .
 . 2 5 9 . . 4 1 8
 . . . . . . 5 . 2
 . . . . . . 6 3 7



 . . . . . . . . .
 4 . . . . . . . .
 2 . 5 7 4 3 9 1 .
 5 . 8 . . . . 6 .
 1 . 9 . 7 8 . 3 .
 3 . 2 . . 6 . 7 .
 9 . 3 2 8 5 . 4 .
 8 . . . . . . 9 .
 7 2 6 4 9 1 5 8 .



 . . . 4 9 8 5 . .
 . . 3 . . . . 2 .
 . 1 . . 3 2 . . 9
 . 5 . 3 . . 6 . 8
 . 3 . . . . 2 . 7
 . . 2 . . 4 . . 3
 2 . . 5 8 . . 7 .
 . 6 . . . . 8 . .
 . . 8 2 1 3 . . .



 . . . 9 8 1 . . .
 . . 4 . . . 7 . .
 . 6 . . . . . 8 .
 6 . . . 3 . . . 5
 3 . . 8 . 6 . . 9
 1 . . . 2 . . . 7
 . 9 . . . . . 4 .
 . . 2 . . . 5 . .
 . . . 4 7 5 . . .

See Sudoku Patterns for a large number of puzzles with a few interesting patterns, one of which is a pattern I came up with. TSO I has 3 empty rows, 3 empty columns and 3 empty boxes -- a total of 9 empty groups, for example:

Code: Select all

. . . . 1 2 . 3 4
. . . . 5 6 . 7 8
. . . . . . . . .
. . . . . . . . .
4 1 . . . . . 8 5
2 9 . . . . . 6 7
. . . . . . . . .
1 2 . . 3 9 . . .
9 8 . . 4 7 . . .

[claudiarabia]

Simple Sudoku says this puzzle has 32 solutions. Is one of the clues entered in the wrong cell?Tracy

I checked the doubted sudoku and I found out that my programm tricked on my. When I invented a pattern and tried to reduce the clues afterwards to make it more ambitious I discovered that Sudoku-Drucker remembers the clues I deleted previously. So it showed still one solution even when there were plenty of them suddenly. After this dreadful discovery I turned to load a completely new sudoku before an upgrade of a sudoku in work and then I'm sure, the programm will have forgotten what I did previously. But thanks to the programm-advice of some members I'll overcome this problems I hope.
I tried several times to rectify the sudoku criticized by TKiel but until now I always chose the wrong body of numbers to mould the desired sudoku-pattern out of it. Maybe it doesn't work at all.

Code: Select all

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

Therefore I created a new sudoku with a pattern I was more successful in and I dedicate it to the alert Tracy:

Code: Select all

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

Claudia

[Ocean]

Simple Sudoku says this puzzle has 32 solutions. Is one of the clues entered in the wrong cell?Tracy

(...)
I tried several times to rectify the sudoku criticized by TKiel but until now I always chose the wrong body of numbers to mould the desired sudoku-pattern out of it. Maybe it doesn't work at all.

Here are three puzzles - small modifications of the multisolution puzzle:

Code: Select all

# S6. Easy puzzle, solves with single eliminations only:
 *-----------*
 |9..|...|.8.|
 |..8|354|..7|
 |.3.|...|2..|
 |---+---+---|
 |.8.|.9.|7..|
 |.1.|2..|9.6|
 |.7.|...|1..|
 |---+---+---|
 |..3|965|.7.|
 |7..|...|5.2|
 |.5.|.4.|.6.|
 *-----------*

Code: Select all

# ND. A bit harder, can be solved with naked pairs:
 *-----------*
 |6..|...|.8.|
 |..8|314|..7|
 |.3.|...|2..|
 |---+---+---|
 |.8.|.9.|7..|
 |.1.|8..|9.6|
 |.7.|...|1..|
 |---+---+---|
 |..3|965|.7.|
 |7..|...|5.2|
 |.5.|.4.|.6.|
 *-----------*

Code: Select all

# XY. More advanced. Can be solved with xy-wing:
 *-----------*
 |6..|...|.8.|
 |..8|324|..7|
 |.3.|...|2..|
 |---+---+---|
 |.8.|.9.|7..|
 |.1.|5..|9.6|
 |.2.|...|1..|
 |---+---+---|
 |..3|965|.7.|
 |7..|...|5.2|
 |.5.|.4.|.6.|
 *-----------*

[ab]

Code: Select all

. . . . 1 2 . 3 4
. . . . 5 6 . 7 8
. . . . . . . . .
. . . . . . . . .
4 1 . . . . . 8 5
2 9 . . . . . 6 7
. . . . . . . . .
1 2 . . 3 9 . . .
9 8 . . 4 7 . . .

You can make that pattern more symmetric with some row swapping:

Code: Select all

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



[tso]

You can make that pattern more symmetric with some row swapping:

True, but the original pattern has an empty 5x5 square in the center -- the largest possible empty square, as well as a 4x4 empty square upper left -- and it still has diagonal mirror symmetry. (Is 5x5 the largest possible empty rectangle as well?)

A comprimise that keeps the 5x5 empty and adds 180 degree rotational symmetry:

Code: Select all

. . . 1 . 2 . 3 4
. . . 5 . 6 . 7 8
. . . . . . . . .
4 1 . . . . . 8 5
. . . . . . . . .
2 9 . . . . . 6 7
. . . . . . . . .
1 2 . 3 . 9 . . .
9 8 . 4 . 7 . . .

[JPF]

Micheal Kennett's program allows you to create any template(s) you wish, though the time it takes to find a match can vary greatly.
...

Could you give an example on how to use this program. (command lines, etc...)

Thanks.

JPF

[ab]

(Is 5x5 the largest possible empty rectangle as well?)

Here's a puzzle with a 7x4 rectangle:

Code: Select all

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



[JPF]

(Is 5x5 the largest possible empty rectangle as well?)

Here's a puzzle with a 7x4 rectangle...

Here's a puzzle with a 6x5 rectangle :

Code: Select all

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

 

with one of its minimal :

Code: Select all

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


JPF

[Ruud]

This is the largest empty rectangle possible: 7x7

Code: Select all

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

It has a unique solution, but the diagonals must also contain digits 1-9. Sudoku-X boldly goes where no classic sudoku has gone before.

Here is a version with less clues, symmetry type I and it solves with singles only:

Code: Select all

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

Ruud.

[m_b_metcalf]

It has a unique solution, but the diagonals must also contain digits 1-9. Sudoku-X boldly goes where no classic sudoku has gone before.

Indeed. Here's one from my collection with a 5 x 7 hollow.

Code: Select all

  .  .  .  8  9  7  .  .  .  X-sudoku
  4  6  .  .  .  .  .  8  9
  .  .  .  .  .  .  .  .  .
  9  7  .  .  .  .  .  5  8
  8  .  .  .  .  .  .  .  7
  3  5  .  .  .  .  .  2  4
  .  .  .  .  .  .  .  .  .
  1  9  .  .  .  .  .  7  6
  .  .  .  7  5  6  .  .  .



Another interesting type is where a partial template is formed of predetermined values, like the digits 1-9 that snake (almost) in order around the perimter of this:

Code: Select all


  1  2  3  4  5  6  7  8  9
  6  .  7  .  .  .  .  .  1
  5  .  .  9  .  .  .  .  2
  4  .  .  .  7  9  .  .  3
  3  .  .  .  .  .  .  .  4
  2  .  .  .  .  .  .  .  5
  9  .  .  .  .  .  .  .  6
  8  3  .  .  .  5  .  .  7
  7  6  5  3  4  2  1  9  8


Regards,

Mike Metcalf

[tso]

Here's a puzzle with a 6x5 rectangle :

Excellent!

This is the largest empty rectangle possible: 7x7

Nice!

This is yet another reason that Sudoku X really should have been the standard puzzle to begin with. Other reasons: Magic Squares, which have common ancestors, always include the two main diagonals -- and every school kid knows that. Diagonals are easy to see, unlike other types of disjoint groups. The two additional groups allow for three cell forcing chains and other modified tactics, making solving potentially more interesting without making more complicated or opaque.

[JPF]

Here's a puzzle with a 8 x 4 empty rectangle :

Code: Select all

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



and one minimal :

Code: Select all

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


any improvement on the Sudoku-X side ?

JPF

[ab]

here's a puzzle with a 39 square rectangle:

Code: Select all

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



[fermat]

This is yet another reason that Sudoku X really should have been the standard puzzle to begin with.

Hello? This whole thing started with humans making grids. There would be. perhaps, one a month instead of several a day.

People are just human, you know?

[tso]

Could you give an example on how to use this program. (command lines, etc...)

Not appropriate to talk about here. I'll PM you. But all you need to know is in the manual in zip file.