Cardinalities of the intervals $(-1,1)$ and $[-1,1]$
33014
Bijection between an open and a closed interval
36315
Is $[0,1]$ a countable disjoint union of closed sets?
10839
Problem in Cardinality and Order
127233
Cardinality of order types in $\mathbb{N}$
100465
Does there exist a continuous bijection from $(-1,1) \to (-1,1]$?
62542
Why is the empty set considered an interval?
5526
Prove that $ℤ[i]^*= \{1,-1,i,-i\}$
39692
The length of an interval covered by an infinite family of open intervals
13398
Prove that the interval $(0, 1)$ and the Cartesian product $(0, 1) \times (0, 1)$ have the same cardinality
44214
The number of subsets of a set of cardinality $n$
138283
$|(a,b)| = |\Bbb R|$ ? Cardinality of any open interval
49440
Prove that the interval $ \ [0,2)$ and $ \ [5,6) \cup [7,8)$ have the same cardinality
24050
Characterization of the Closure of a Set
70164
Proof exercise that the cardinal number of a set in $\mathbb R^2$ is $\frak c$
66239
Verifying that a certain collection of intervals of $\mathbb R$ forms a topology
31318
Cardinality of cartesian square
7785
Cardinality of sum-set