How is this classical group $\textit{compact}$?
69497
Show that the set of all $n \times n$ orthogonal matrices, $O(n)$, is a compact subset of $\mbox{GL} (n,\mathbb R)$
95234
Quasi-components in compact space
71245
$2 \times 2 $ Orthogonal Group
105139
Verification of Proof that a nonabelian group G of order pq where p and q are primes has a trivial center
128457
Show that $T$ is a compact operator
90778
Faithful representation of the Heisenberg group
11000
Fundamental group of $\mathbb{R}^2 \setminus (\mathbb{Z} \times \{0\})$
52802
Why is the image of $k^+$ dense in the character group?
146455
Compactness of the set of all unitary matrices in $M_2(\mathbb{C})$
87922
Computing the Lie bracket on the Lie group $GL(n, \mathbb{R})$
54346
If $G$ is a compact topological group, how to show that a finite index subgroup of $G$ is open?
33294
The correspondence theorem for groups
26256
Characterizing Dense Subgroups of the Reals
141642
Closure of a certain subset in a compact topological group
36631
Is $[0,1] \cap \Bbb Q$ a compact subset of $\Bbb Q$?
46001
Can a finite group act freely (as homeomorphisms) on $\mathbb R^n$
22464
Which of the following subsets of   $\mathbb{R}^2$ are compact