Perfect set without rational numbers
12701
Perfect set without rationals
45911
Prove that none of $\{11, 111, 1111,\dots \}$ is the perfect square of an integer
103744
Minimal $ab$ for Rational Number $a/b$ in an Interval
126015
Elementary number theory in sets
158882
Prove the existence of some weird family of sets
132382
Showing a set is nowhere dense in $C([0,1])$
156006
Cardinality of set containing all infinite subsets of $\mathbb{Q}$
93771
Prove that for any set $A$ there is some $x \notin A$
5098
Theorem without numbering
18360
Proof that the irrational numbers are uncountable
100565
Property of sup of a set of numbers
9146
Proving that a list of perfect square numbers is complete
80019
$\varepsilon$-number countability without choice
142583
Subsets of the Cantor set
151686
A proof that the Cantor set is Perfect
113668
Uncountable chain of subsets of $\mathbb N$
100977
Infinite subset with pairwise comprime elements