Finite union of closed set is closed
95244
Prove that a finite union of closed sets is also closed
127173
Closed subset of compact set is compact
111008
Show that $X $ is a infinite set ,it is connected in the finite complement topology?
142228
Proof that a subset closed under group operation of a finite group is a subgroup
36237
Closed set mapped to itself in a compact Hausdorff space
84936
The set of all finite sequences of members of a countable set is also countable
138202
Every open set in $\mathbb{R}$ is a countable union of closed sets
132868
Bijection between an infinite set and its union of a countably infinite set
144353
A closed ball in a metric space is closed
128482
The set of subsequential limits is closed
136851
Proof that the set of subsequential limits is closed
106957
Compact sets are closed?
64871
Closure of Union contains Union of Closures
84512
The preimage of continuous function on a closed set is closed.
107975
Show that the class of regular languages is closed under shuffle
82333
let $(X,d)$ be a metric space. How I can show that any finite subset of $X$ is closed.
102170
Showing a Sequence and its Limit are Closed