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Some pretty 8-way symmetry puzzles.

 
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The Ostrich

Joined: 20 Apr 2006
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PostPosted: Thu Apr 27, 2006 1:15 pm    Post subject: Some pretty 8-way symmetry puzzles. Reply with quote

I've been implementing arbitrary symmetries for my generator today, and I've at last got some 8-fold symmetry puzzles. Not that its anything special...

By the standards of this forum, they are all middle-rating puzzles. But they sure do look pretty.




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gsf

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PostPosted: Thu Apr 27, 2006 2:46 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

can you post in snarfable form?
thanks
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m_b_metcalf

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PostPosted: Sun Apr 30, 2006 3:14 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

Quote:
I've been implementing arbitrary symmetries for my generator today, and I've at last got some 8-fold symmetry puzzles.


I agree these higher symmetries are pretty, but it's hard to generate very difficult ones. Here's another selection, all with at least 2-way mirror symmetry (left-right, up-down), in decreasing order of difficulty.

Regards,

Mike Metcalf

Code:

        5           8     
  9                       1
  8     6     9     4     7
     9     8     2     4   
        4     3     1     
     8     1     6     2   
  3     8     6     9     2
  1                       3
        2           5     
 
 Difficulty Index 29

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

 Difficulty Index 29

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

 Difficulty Index 25

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

 Difficulty Index 24

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

 Difficulty Index 21

     8     9  2  3     1   
           8     6         
        3     4     8     
  7  2                 3  6
  6                       8
  9  4                 2  1
        2     5     1     
           6     8         
     5     2  3  1     7   
 
 Difficulty Index 23

     8     9     2     3   
     2        4        6   
        6           2     
     5  3           6  9   
  9  1                 7  3
     6  7           1  4   
        5           3     
     4        7        1   
     3     1     9     5   
 
 Difficulty Index 21

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

 Difficulty Index 18

           8  4  7         
        8  1     6  7     
     7        5        6   
     1  7           4  8   
  2                       9
     9  6           1  3   
     3        8        9   
        2  7     5  8     
           9  2  4         
 
 Difficulty Index 18
  0                       
     3  8     4     9  5   
     4  5  6     7  3  2   
  4  6                 8  1
                           
  8  1                 7  3
     2  4  7     3  1  6   
     8  6     2     4  9   
  0                       

 Difficulty Index 17

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

 Difficulty Index 16

           7     1         
           4  2  3         
  8  3        5        1  2
  7  4                 3  6
     6  8           2  9   
  3  9                 5  7
  9  8        3        6  1
           1  9  8         
           6     7         
 
 Difficulty Index 15

        2  6  5  4  3     
                           
  6        8     1        7
  1  8  3  7     2  6  5  9
  9                       1
  5  2  6  9     8  7  4  3
  4        1     9        6
                           
        7  4  8  6  9     
 
 Difficulty Index 14

  5  3                 1  8
     7  2           6  3   
        6  9     2  5     
           4  6  9         
           3     8         
           1  2  7         
        5  2     3  8     
     2  3           9  5   
  8  9                 4  2
 
 Difficulty Index 12

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

 Difficulty Index 12

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

 Difficulty Index 12

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

 Difficulty Index 11

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

 Difficulty Index 10

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

 Difficulty Index 9
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gsf

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PostPosted: Sun Apr 30, 2006 8:24 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

m_b_metcalf wrote:
Quote:
I've been implementing arbitrary symmetries for my generator today, and I've at last got some 8-fold symmetry puzzles.


I agree these higher symmetries are pretty, but it's hard to generate very difficult ones. Here's another selection, all with at least 2-way mirror symmetry (left-right, up-down), in decreasing order of difficulty.

another unsnarfable puzzle post
can we please post puzzles in [ code ] ... [ /code ] and with . or 0 for empty cells
thanks
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rkral

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PostPosted: Sun Apr 30, 2006 8:52 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

gsf wrote:
can we please post puzzles in [ code ] ... [ /code ] and with . or 0 for empty cells
thanks

I echo that sentiment ... and add that the dots ('.') are much better than zeroes ('0') because clues seem "lost" in the sea of zeroes.
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Ruud
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PostPosted: Sun Apr 30, 2006 10:40 pm    Post subject: Reply with quote

I already copied the first 4. Here they are, snarf-ready:

Code:
000602000008010500020809070403000607060000040205000109050203090009080700000401000
040000080301000602050201070008010400000708000007060900080305090105000803020000060
000000000009803200056090340090030080008107500030050010043080120007301900000000000
000584000008000400060010090800105004502000107400803002080050030007000500000268000


I have not looked at the others yet.

A sticky about how to post puzzles is in the making...

Ruud.
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m_b_metcalf

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PostPosted: Mon May 01, 2006 12:23 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

Quote:
another unsnarfable puzzle post


What does that mean. Is snarf some O/S-dependent feature?

Regards,

Mike Metcalf
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m_b_metcalf

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PostPosted: Mon May 01, 2006 12:31 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

Quote:
can we please post puzzles ... with . or 0 for empty cells
thanks


That's silly in this case. The whole point of this thread is to show 'pretty' puzzles. Drowning them in a sea of 0s or .s only serves to obscure them by lowering the signal-to-noise ratio. I've never seen a sudoku in print with 0s or .s. Why do programs need them? Surely computers are there to serve humans, not the other way around.

Regards,

Mike Metcalf
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rkral

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PostPosted: Mon May 01, 2006 2:42 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

m_b_metcalf wrote:
Quote:
can we please post puzzles ... with . or 0 for empty cells
thanks

That's silly in this case. The whole point of this thread is to show 'pretty' puzzles. Drowning them in a sea of 0s or .s only serves to obscure them by lowering the signal-to-noise ratio.

We can "cut & paste" this ...
Code:

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

... into neither Angus Johnson's Simple Sudoku nor Ruud's Sudo Cue. We can do either with this ...
Code:

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

I don't think there's enough difference in "prettiness" to warrant most everyone needing to cut & paste the former into an editor ... then edit ... and then cut & paste into programs.

However, I agree zeroes would be totally inappropriate in the grid format ... but I don't think anyone is suggesting that. The zeroes are an alternative in the line format though IMO.
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gsf

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PostPosted: Mon May 01, 2006 3:16 pm    Post subject: Re: Some pretty 8-way symmetry puzzles. Reply with quote

m_b_metcalf wrote:
Quote:
can we please post puzzles ... with . or 0 for empty cells
thanks


That's silly in this case. The whole point of this thread is to show 'pretty' puzzles. Drowning them in a sea of 0s or .s only serves to obscure them by lowering the signal-to-noise ratio. I've never seen a sudoku in print with 0s or .s. Why do programs need them? Surely computers are there to serve humans, not the other way around.

this is the programmer's forum
(although I would make the same argument for the players forum)
many of the readers analyze posted puzzles
especially ones associated with claims that can be computed
rkal shows that .'s don't get in the way when borders are eliminated

and in this particular case there is a similar thread on the player's forum
that is cataloging fully symmetric puzzles, where programs are used to
verify puzzle uniqueness (i.e., up to isomorphism) and symmetry types

I mentioned 0 as a computational alternative, but also to emphasize
(by omission) that other empty cell charaters (like - _ x) may be problematic for
solvers that attempt to discern 9x9 grids from pencilmark grids

another comment: a snarfable form should not be positional, e.g.,
"the odd character positions hold clues", because errant spacing,
either in the rendering of the puzzle to be snarfed, or in the snarf itself,
could skew the positional data
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The Ostrich

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PostPosted: Wed May 03, 2006 1:53 am    Post subject: Reply with quote

Sorry about the unsnarf problem. Stupidity. Cheers Ruud for fixing my problem for me. When I made the puzzles, I didn't have clipboard support set up. Now I do, so it becomes easier to post them. I use the standard Rubylips / Into Sudoku format with dots, lots of spaces and vertical + horizontal separators. My program won't, however, recognise a Sudoku that uses spaces as the blank character. I wonder if anyone has any thoughts about which clipboard formats a program should be able to recognise etc...?
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Ruud
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PostPosted: Wed May 03, 2006 2:22 am    Post subject: Reply with quote

The Ostrich wrote:
I wonder if anyone has any thoughts about which clipboard formats a program should be able to recognise etc...?

My program can recognize any string that contains:

Digits 1-9 + one character that completes the count to 81.

or

81 groups of digits 1-9. (candidate grid)

all other characters are ignored.

Ruud.
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