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Old 2008 December 17th, 12:59 PM   #3 (permalink)
oldmathguy
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Join Date: Dec 2008
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The question must have been about "homeomorphic" not "homomorphic":
It's a topology question.
C is homeomorphic to N, S and U since all four of these letters can't
be straightened out to (are homeomorphic to) a line segment.

C is not homeomorphic to J because if we take away the top middle point
of the J we are left with three connected components, while this cannot
happen with any point of C. (Using: If X is homeomorphic to Y and x is
element of X and y is element of Y then X-{x} is homeomorphic to Y-{y}.)

C is not homeomorphic O because the latter has a loop in it that can't
be shrunk to a point in it. (Technically, they have different fundamental
groups -- not a concept that would be on the GRE.)
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