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Symmetry - yea or nay?

 
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Should symmetry be a requirement for valid sudoku?
yes
9%
 9%  [ 2 ]
no
90%
 90%  [ 20 ]
Total Votes : 22

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BTUx9

Joined: 24 Jul 2005
Posts: 4
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PostPosted: Sun Jul 24, 2005 3:36 am    Post subject: Symmetry - yea or nay? Reply with quote

I can understand the disagreements where T&E are concerned... it's a gray and wavy line between "logic" solutions and "limited-guess" ones, but is there a consensus as to whether symmetry is required for a "valid" puzzle? I don't see where it really adds value, and it seems that it's easier to find challenging puzzles without the constraints of rot-2 or other symmetry.
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angusj
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Joined: 18 Jun 2005
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PostPosted: Sun Jul 24, 2005 3:51 am    Post subject: Re: Symmetry - yea or nay? Reply with quote

BTUx9 wrote:
but is there a consensus as to whether symmetry is required for a "valid" puzzle?

I'd be surprised if anyone argued that lack of symmetry constituted an 'invalid' puzzle, but many would argue it detracted from the aesthetics of the puzzle.

Also, since there are literally billions and billions of puzzles to chose from, I really don't think it's an issue to skip those that lack symmetry.

Having said that, I have absolutely no objection to puzzles that lack symmetry - to me the much greater appeal is in the variety of solving techniques required to complete them.


Last edited by angusj on Sun Jul 24, 2005 4:13 am; edited 1 time in total
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BTUx9

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PostPosted: Sun Jul 24, 2005 3:57 am    Post subject: Reply with quote

That happens to be my opinion, too... the aesthetics of a devilish puzzle are much more interesting to me than the position of the numbers.
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chuckfresno

Joined: 16 Jun 2005
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PostPosted: Sun Jul 24, 2005 4:57 am    Post subject: Reply with quote

I agree with Argusj and I would add another point. From the point of view of the person solving, a symmetrical puzzle -- be it a Sudoku or a Crossword -- implies that the composer put more into it. Maybe it shouldn't seem that the composer just whipped it off without thinking. Of course, this is all mute now that most are computer generated.

Just an opinion, but if there is some *reason* to make it without symmetry or a non-symmetrical by obvious pattern, to set-up a particular tactic that couldn't be express easily in a symmetrical layout, that seems ok. Hardest ever, least clues, most protracted chain of reasoning, largest sequence of x-wings, whatever. Otherwise, it just seams sloppy.
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BTUx9

Joined: 24 Jul 2005
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PostPosted: Sun Jul 24, 2005 5:08 am    Post subject: Reply with quote

It's not sloppy if it's a considered choice. I don't want all of my puzzles with an odd # to have the center square filled (the only choice for those with rotational symmetry of 3x3 puzzles) and you can't even GET an odd number with 4x4 puzzles (again, with rotational symmetry, which seems to be the most common).
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Ruud
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Joined: 17 Sep 2005
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PostPosted: Fri Sep 23, 2005 12:14 am    Post subject: Reply with quote

As soon as you start solving the puzzle, the symmetry is lost anyway... Cool
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Mike G

Joined: 16 Jun 2006
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PostPosted: Fri Jun 16, 2006 7:14 pm    Post subject: Reply with quote

Not necessarily. The solution itself might have symmetry, up to an uninteresting permutation of the symbols filling the cells. To give a random example, this grid
Code:
564 782 193
927 413 856
831 659 742

495 278 361
618 534 927
273 961 485

156 847 239
749 325 618
382 196 574
is not changed essentially by rotation through 180 degrees.

Has anyone looked into the setting of problems with symmetrical solutions? Perhaps with an unsymmetrical distribution of clues such as
Code:
5.4 ... 1..
.27 ... ..6
.3. ..9 .42

... 2.. ...
.1. 5.. ...
..3 .6. ...

1.. ..7 .3.
... ... 618
..2 .9. 5..
for the example given above.
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crosspollinator

Joined: 24 Jun 2006
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PostPosted: Sat Jun 24, 2006 3:28 am    Post subject: Reply with quote

I try to make all of my puzzles aesthetically pleasing. To me, that is more important than whether or not they are symmetrical. Most computer-generated puzzles aren't very interesting to look at, whether or not they are symmetrical. I've written several programs to help me create puzzles, but I haven't suceeded in writing a program that generates aesthetically pleasing puzzles without human input.
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