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 Can you match them up? (Posted on 2006-09-21)
A function f:A→B from set A to set B is called a bijection if it is a one-to-one correspondence between A and B, i.e. for every b in B there is exactly one a in A such that f(a)=b. More informally, you could say that every element in A gets matched up with exactly one element in B and vice versa.

Can you give examples for bijections between the following sets?

1. A=(0,1), B=R

2. A=[0,1]², B=the unit disc with boundary, i.e. all points in the plane with distance smaller or equal 1 from origin

3. A=[0,1], B=the unit circle, i.e. all points in the plane with distance 1 from the origin.

4. A=[0,1], B=the unit disc with boundary

 No Solution Yet Submitted by JLo No Rating

Comments: ( Back to comment list | You must be logged in to post comments.)
 first one is easy; the rest hard | Comment 1 of 6
1. b=f(a) = tan(pi*(a-.5))
 Posted by Charlie on 2006-09-21 14:08:22

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