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The Fugitive
Joined: 28 Aug 2005 Posts: 10

Posted: Wed Mar 22, 2006 8:00 pm Post subject: Duplicate puzzles #2 


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

Posted: Wed Mar 22, 2006 9:00 pm Post subject: 


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

Posted: Thu Mar 23, 2006 12:31 pm Post subject: Re: Duplicate puzzles #2 


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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Guest

Posted: Thu Mar 23, 2006 7:14 pm Post subject: 


OK, Sorry I misunderstood your point. 

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George Woods
Joined: 28 Mar 2006 Posts: 270 Location: Dorset UK

Posted: Sat Apr 01, 2006 7:38 pm Post subject: Disguising identical sudoku 


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: 3257 Location: near Detroit, Michigan, USA

Posted: Sat Apr 01, 2006 9:41 pm Post subject: Number of puzzles 


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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