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Duplicate puzzles #2

 
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The Fugitive



Joined: 28 Aug 2005
Posts: 10

PostPosted: Wed Mar 22, 2006 8:00 pm    Post subject: Duplicate puzzles #2 Reply with quote

Apologies if these have already been picked up, but the following classic puzzles are exact duplicates:

15/06/05 and 01/08/05 (already noted in a previous post)
01/10/05 and 03/01/06
02/10/05 and 02/01/06
03/10/05 and 05/01/06
08/10/05 and 06/01/06
11/10/05 and 20/01/06
14/10/05 and 19/01/06
17/10/05 and 22/01/06
20/10/05 and 26/01/06
22/10/05 and 28/01/06
29/11/05 and 18/02/06

List up to date as of today, 22nd March 2006.
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Guest






PostPosted: Wed Mar 22, 2006 9:00 pm    Post subject: Reply with quote

Does it matter? Do you actually remember how you solved it months before? Perhaps you've learnt something new in the meantime and it's different now.

Let's be grateful that these fantastic puzzles appear here every day.
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The Fugitive



Joined: 28 Aug 2005
Posts: 10

PostPosted: Thu Mar 23, 2006 12:31 pm    Post subject: Re: Duplicate puzzles #2 Reply with quote

I'm only pointing out duplicates, not passing judgement. It matters simply because its information and might suggest a problem in the author's puzzle generator.
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PostPosted: Thu Mar 23, 2006 7:14 pm    Post subject: Reply with quote

OK, Sorry I misunderstood your point.
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George Woods



Joined: 28 Mar 2006
Posts: 232
Location: Dorset UK

PostPosted: Sat Apr 01, 2006 7:38 pm    Post subject: Disguising identical sudoku Reply with quote

There are over 60 billion variants of most soduku puzzles,

Not only can the numbers be reassigned, but any of top3 middle3 or bottom 3 rows can be juggled. same goes for columns, and finaly exactly the same goes for blocks of 3 for columns and rows and that makes 6 to power 8 multiplied by 8! different versions of the same puzzle

Even if my maths aren't quite right, (for instance a puzzle might have no 9's showing or have a starting symmetry), there are clearly very many variants of the same puzzle- But the differences are superficial, since the same techniques are needed to solve all those variants (I think)!

Just a thought!
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keith



Joined: 19 Sep 2005
Posts: 3165
Location: near Detroit, Michigan, USA

PostPosted: Sat Apr 01, 2006 9:41 pm    Post subject: Number of puzzles Reply with quote

George,

Take a look at Wikipedia. http://en.wikipedia.org/wiki/Sudoku

Quote:

(edited by keith)

The number of valid Sudoku solution grids is 6,670,903,752,021,072,936,960. This number is equal to 9! 722 27 27,704,267,971, the last factor of which is prime. When symmetries are taken into account, there are 5,472,730,538 solutions.

("Valid" means unique, a single solution.)



So there are 5.5 (American) billion Sudoku SOLUTIONS which are not symmetric with any other. Presumably, each of these solutions has many possible starting grids.

I do not think we will soon be bored!

Best wishes,

Keith
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