How can $\mathbb{I}$ be uncountable and $\mathbb{Q}$ countable, yet $\forall a,b \in \mathbb{R} \exists r \in \mathbb{Q} : a<r<b$
34825
Intuitive explanation for how could there be "more" irrational numbers than rational?
85032
$Q(\mathbb{Z}[t]) / \mathbb{Z}[t]$ is not injective
9021
An infinite subset of a countable set is countable
113668
Uncountable chain of subsets of $\mathbb N$
136106
Is every open subset of $ \mathbb{R} $ uncountable?
86685
Example of a set $S$ that is countable, but the set of limit points is uncountable
66301
The cardinality of the set of countably infinite subsets of an infinite set
124847
Is the set of surjective functions from $\mathbb{N}$ to $\mathbb{N}$ uncountable?
19297
Is the cofinite topology on an uncountable set first countable?
23907
$Seq (\mathbb{N})$ of all finite sequences of elements of $\mathbb{N}$ is countable.
18360
Proof that the irrational numbers are uncountable
136321
Show that if $\sup\big\{\sum\lvert\, f(a)\rvert\big\}  0\}$ is countable.
145471
$\Gamma \subset \mathbb{R}^{+}$ is uncountable. Can we choose a sequence from $\Gamma$ of which the sum is $\infty$
23442
Cardinality of the union of infinite and countable sets
37398
Proof that$ (a+A)\cap A=\varnothing$ if $A$ is countable
3645
Why Are the Reals Uncountable?
62793
$\mathbb{R}$ with the lower limit topology is not second-countable