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Topic: can a wristband be turned inside-out?
Replies: 2   Last Post: Jun 16, 1996 9:55 AM

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Mike McCarty

Posts: 1,182
Registered: 12/6/04
Re: can a wristband be turned inside-out?
Posted: Jun 14, 1996 7:06 PM
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In article <4pg92l$gtd$>,
Mike Kent <70530.1226@CompuServe.COM> wrote:
)The original posting asked for the band to be deformed
)"continuously and isometrically". I take this to require
)a continuous function D: [0,1] x W -> W for which D(0,w) = w
)for all w in the wristband W, and for which the distance
)(along a geodesic) between w1, w2 in W is the same as the
)distance between D(r,w1) and D(r,w2) (along a geodesic) in
)the image D(r,W).
)I don't have an answer, of course, but I think this states
)the problem a bit more formally.

So long as you don't add "differentiably", it -can- be done. So long as
the wristband is not too "tall".

It takes folding. A charming little puzzle has a cardboard band colored
black on one side, and white on the other. The puzzle is to turn it
inside out.

See one of Martin Gardner's puzzle books on this.

Sorry, I forget which one.

char *p="char *p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

I don't speak for DSC. <- They make me say that.

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