What is the logical criterion used to place the four different symbols that fills the 36 cells of the 6 x 6 grid ?
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| O | # | x | @ | # | O |
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| @ | O | O | x | x | @ |
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| @ | x | O | # | # | @ |
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| # | @ | @ | x | O | # |
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| # | O | O | x | x | # |
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| x | @ | # | O | @ | x |
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I thought about this problem in a different way than the other people who posted comments. What I came up with is perhaps less a criterion for placing the symbols as it is a descriptor of their placement, but I still think it's interesting. Here are my thoughts:
Let x = 0, and
Let @ = #
Then the grid has 180-degree rotational symmetry around the center point.
The problem with this is that, if this were the criterion for placement, then the grid shown would be one of several possible solutions, not the only solution.
Given the actual criterion for symbol placement (see solution), can anyone explain why the rotational symmetry works?
-- Becky
Symmetry
