Saturday, January 4, 2020

real analysis - Which of the following is uncountable?


Which of the following is uncountable?



$1.\{f|f:\{0,1\}\to\mathbb{Z}\}$


$2.\{f|f:\mathbb{Z}\to\{0,1\}\}$


My attempt:I think first is countable because we can make a bijection from this to $\mathbb{Z^2}$,am I correct?About second option I do not have any idea.


Thanks.


Answer



Hint for 2: $\{f\mid f:\mathbb{Z}\to\{0,1\}\}$ has the same cardinality as the power set of $\mathbb{Z}$.


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