Saturday, 22 June 2013

real analysis - Is there a continuous bijection between an interval [0,1] and a square: [0,1]times[0,1]?



Is there a continuous bijection from [0,1] onto [0,1]×[0,1]?
That is with I=[0,1] and S=[0,1]×[0,1], is there a continuous bijection

f:IS?



I know there is a continuous bijection g:CI from the Cantor set C to [0,1].
The square S is compact so there is a continuous function
h:CS.
But this leads nowhere.
Is there a way to construct such an f?




I ask because I have a continuous functional F:SR.
For numerical reason, I would like to convert it into the functional
G:IR,G=Ff,
so that G is continuous.


Answer



No, such a bijection from the unit interval I to the unit square S cannot exist. Since I is compact and S is Hausdorff, a continuous bijection would be a homeomorphism (see here). But in I there are only two non-cut-points, whereas in S each point is a non-cut-point.


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