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Old 09-July-2009, 09:46 PM
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tdvance tdvance is offline
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Join Date: Apr 2006
Location: Bowie, MD
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Quote:
Originally Posted by Frog march View Post
well, I wasn't sure what I was asking.


I suppose that you could define the 8 corners of a 4D cube, with different length sticks(with the ends being the defining points)....It's going to be my entry for the Turner prize..

does a cube even have only 8 corners in 4D?
Yes, but a hypercube has 16 corners

OT but: Actually, there's a formula for number of r-faces in an n-cube--

r is the dimensionality of the face: 0 for corner, 1 for edge, etc., n the dimensionality of the (solid) cube, 0 for a single point, 1 for a line segment, 2 for a square, 3 for a cube, 4 for a 4-d hypercube, etc.

The number of r-faces in an n-cube is 2^(n-r) * (n choose r)

One way to think of an n-cube is the set of all n-coordinate points

(a,b,c,d,...,x) with each coordinate being between 0 and 1 inclusive.

Then, an r-dimensional face of the n cube is selected by choosing n-r of the coordinates (n choose r ways to do so, since n choose r = n choose n-r), and consider all possible ways of making them 0 or 1 (2^(n-r) ways to do so). Each choice gives a face--and the other points, taking values from 0 to 1, define the r-dimensional coordinates on that face.
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