Cardinality between union of open uncountable set with finite set

32 Views Asked by At

I am trying to show that $|(0,1)| = $$|(0,1) \cup ${$2,3,4,5$}$|$ using the Schroder-Bernstein Theorem.

Therefore, I need to find injections

  1. $f:(0,1) \rightarrow (0,1) \cup ${$2,3,4,5$} and

  2. $g:(0,1) \cup ${$2,3,4,5$} $\rightarrow (0,1)$

(1) We can define $f(x)=x$ since we do not have to consider 2,3,4,5.

(2) We can define $g(x)= \frac{x}{6}$ in order to direct 2,3,4,5 to a number $\in (0,1)$

Therefore, by the Schroder-Bernstein Theorem, $|(0,1)| = $$|(0,1) \cup ${$2,3,4,5$}$|$

Is this valid?