How to prove that $\{1/n\}\cup \{0\}$ is compact by open covers?
117781
Proving that $S=\{\frac{1}{n}:n\in\mathbb{Z}\}\cup\{0\}$ is compact using the open cover definition
36631
Is $[0,1] \cap \Bbb Q$ a compact subset of $\Bbb Q$?
70264
Prove that the inverse image of an open set is open
116542
Which of the following sets are compact in $\mathbb{M}_n(\mathbb{R})$[NBHM_PhD Screening Test-2013, Topology]
28391
Prove the compactness of a set B
81927
Example of closed and bounded in $\mathbb Q$ set that is not compact
152193
The intersection of a closure with an open set
38946
Show that $\{\cup_{n\in K} (n, n+1]: K \subset \mathbb{Z}\}$ is a $\sigma$-algebra on $\mathbb{R}$
65358
Prove $X$ is compact iff for each family $\{ F_\alpha\}_{\alpha\in I}$ of closed subsets of $X$ with the FIP, we have $\cap F_\alpha\neq\varnothing$.
128334
Question regarding open covers in Zariski topology (distinguished opens of affine schemes are quasi-compact)
88130
Infinite product $\prod_k (1-z/a_k)(1-z/b_k)^{-1}$ converges uniformly on compacts of$\{\mathbb Im z>0\}$ and is Herglotz
1756
1-point compactification and embedding
102048
Closure of a compact set in Regular space $ X $
107370
An open covering of $\mathbb{Q} \cap [0,1]$ that does not contain any finite subcovering
127720
Prove that $\bigcup_{n \in \Bbb{N}} [1/n,1] = (0,1]$.
158498
$A\subset \mathbb{R}$ with more than one element and $A/ \{a\}$ is compact for a fixed $a\in A$
99675
A closed ball in $l^{\infty}$ is not compact