Does there exist a continuous onto function from R−Q to Q?
(where domain is all irrational numbers)
I found many answers for contradicting the fact that there doesnt exist a continuous function which maps rationals to irrationals and vice versa.
But proving that thing was easier since our domain of definition of function was a connected set, we could use that connectedness or we could use the fact that rationals are countable and irrationals are uncountable.
But in this case those properties are not useful. I somehow think that baire category theorem might be useful but I am not good at using it.
Answer
Yes. Say En is the set of irrationals in the interval (n,n+1). Say (qn) is an enumeration of Q. Define f(x)=qn for x∈En.
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