Is product of two closed sets closed?
140103
If product of two sets $A\times B$ is closed, are $A$ and $B$ closed?
11405
If a nonempty set of real numbers is open and closed, is it $\mathbb{R}$? Why/Why not?
35855
Closed form for an infinite product
78117
Closed property of nonempty finite set
21114
$S=\{(n,{1\over n}):n\in\mathbb{N}\}$ is closed in $X$?
97373
Is whether a set is closed or not a local property?
27937
Cartesian Product of Two Countable Sets is Countable
58004
showing a collection of sets contain all closed sets
5323
Example to show the distance between two closed sets can be 0 even if the two sets are disjoint
111538
If $S \subseteq X$ is closed, is $f(S,r)$ necessarily closed?
82900
Show that Minkowski sum of a closed set and a compact set in $\mathbb{R}^n$ is closed.
149820
How do you prove the set $G = \{(x, f(x)) \mid x \in \mathbb R\}$ is closed?
46698
Showing a set is closed under inverses
108740
$C^1[a,b]$ is closed in $C[a,b]$
50026
Product of compact and closed in topological group is closed
70959
Prove that a set $E$ is closed iff it's complement $E^{c}$ is open
137460
How should I think of an open vs. closed set?