Interior of closure of open set in topological space
99236
Interior of closure of an open set
148213
Given a topological space $X$, why are both $X$ and $\emptyset$ open and closed?
127575
Prove that Open Sets in $\mathbb{R}$ are The Disjoint Union of Open Intervals Without the Axioms of Choice
141642
Closure of a certain subset in a compact topological group
128730
Open subspaces of locally compact Hausdorff spaces are locally compact
32723
Open sets and holomorphic functions in Complex analysis
50344
What is the closure of an open ball $B_X(\mathbf{a},r)$ in $X=\mathbb{R}^n$?
27661
The closed graph theorem in topology
129081
Proof that convex open sets in $\mathbb{R}^n$ are homeomorphic?
136108
Arbitrary intersection of closed, connected subsets of a compact space connected?
12293
Let X be a T1 space, and show that X is normal if and only if each neighbourhood of a closed set F contains the closure of some neighbourhood of F
24050
Characterization of the Closure of a Set
49220
Open Sets of $\mathbb{R}^1$ and axiom of choice
30079
Is for open connected $U$ the set $U_\varepsilon$ for small $\varepsilon$ connected?
51156
Function is Continuous When Restricted to Closed Sets Which Cover the Space
73353
Is it true that a subset that is closed in a closed subspace of a topological space is closed in the whole space?
42494
The boundary is a closed set