The Boundary of a Hypercube
The boundary of a solid hypercube?
$\partial(I\times I\times I\times I)$ |
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$=$ |
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$\partial((I\times I)\times(I\times I))$ |
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$=$ |
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$\partial(\square\times\square)$ |
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$=$ |
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$(\partial\,\square\times \square)\cup (\square\times
\partial\,\square)$ |
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$=$ |
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$(\box\times\square)\cup(\square\times\box)$ |
Two congruent pieces, but what are they?
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