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2x2 / 16 grids mathematics of - am i right ?
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calimero

Joined: 06 Jul 2006
Posts: 2
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PostPosted: Thu Jul 06, 2006 3:17 pm    Post subject: Reply with quote

Nick70 wrote:
If you look only at the unique solutions, there are only two grids:

1234 1234
3412 3421
2143 2143
4321 4312

every other grid can be obtained from one of these two by permutating the digits, swapping rows or columns common to a box, rotating or flipping the whole grid.

Interesting theorem, Nick70... Which transformations would you apply to:
1 2 3 4
3 4 1 2
2 3 4 1
4 1 2 3
to make it one of the two unique solutions above?
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Ruud
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Joined: 17 Sep 2005
Posts: 708
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Location: Netherlands

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PostPosted: Thu Jul 06, 2006 4:09 pm    Post subject: Reply with quote

Since Nick has posted his theorem more than a year ago and is unlikely to answer, I'll reply instead:

1 2 3 4
3 4 1 2
2 3 4 1
4 1 2 3

Step 1: rotate 270 degrees

4 2 1 3
3 1 4 2
2 4 3 1
1 3 2 4

Step 2 swap upper - lower bands

2 4 3 1
1 3 2 4
4 2 1 3
3 1 4 2

step 3: relabel digits

1 2 3 4
4 3 1 2
2 1 4 3
3 4 2 1

Ruud.
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calimero

Joined: 06 Jul 2006
Posts: 2
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PostPosted: Thu Jul 06, 2006 4:17 pm    Post subject: Reply with quote

Thanks Ruud... this looks very interesting. I'm reading through the rest of the posts to find more useful information, but was this generalized to n^2 x n^2?
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