Let A be an uncountable set, B a countable subset of A, and C the complement of B in A. Prove that there exists a one to one correspondence between A

Ava-May Nelson

Ava-May Nelson

Answered question

2021-05-19

Let A be an uncountable set, B a countable subset of A, and C the complement of B in A. Prove that there exists a one to one correspondence between A and C.

Answer & Explanation

Nicole Conner

Nicole Conner

Skilled2021-05-20Added 97 answers

Let B=b0,b1,b2,...
If C were finite, we would have that A=BС is countable, which is a contradiction. Thus C is infinite, thus it has a countable suset DC.
Let: D=d0,d1,d2,...
Then we can define a function f: AC f(x)={d2,x=b;d2+1,x=d;x,xA(BD)

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