Find a basis of clopen sets for the topology on $X$
92526
Collection of clopen sets form a base for a countable completely regular space
108864
Showing that two topologies give rise to the same topology
78344
Nonconstant linear functional on a topological vector space is an open mapping
99353
Topology on cartesian product and product topology.
82825
Proving set of interiors is open
148213
Given a topological space $X$, why are both $X$ and $\emptyset$ open and closed?
114437
Why is this the basis for the indiscrete topology?
25256
When a lattice is a lattice of open sets of some topological space?
21176
Closure of the set in dictionary order topology.
103717
Topological Property of the Set of Integers
73130
A simple question about open set
24050
Characterization of the Closure of a Set
69283
The limit points of an open interval (open set)
30231
The boundary of union is the union of boundaries when the sets have disjoint closures
111008
Show that $X $ is a infinite set ,it is connected in the finite complement topology?
36237
Closed set mapped to itself in a compact Hausdorff space
84104
Definition of neighborhood and open set in topology