Is collapsing a contractible closed subspace a homotopy equivalence?
93263
Can contractible subspace be ignored/collapsed when computing $\pi_n$ or $H_n$?
133413
Proof of paracompactness of CW-complexes (J. Lee, Introduction to Topological Manifolds)
2198
Maps from subsets of $\mathbb{R}^2$ that are either open/closed/continuous
97761
Show that a proper continuous map from $X$ to locally compact $Y$ is closed
63442
Show that if $U$ is an open connected subspace of $\mathbb{R}^2$, then $U$ is path connected
144731
Disjoint closed sets in a second countable zero-dimensional space can be separated by a clopen set
34712
Decomposable elements of $\Lambda^k(V)$
106534
"Closed subsets of compact space are compact" with an alternative definition of covering
67259
Can we prove that a bounded closed subset of $\mathbb R^n$ is compact without Axiom of Choice?
36237
Closed set mapped to itself in a compact Hausdorff space
156904
Homotopy Extension Property: necessary and sufficient condition
17165
Is total boundedness a topological property?
153256
Compact topological space with closed graph implies continuity
39010
Metrization of the cofinite topology
81550
Linking two theorems: on algebraic closure and on minimal splitting field
136108
Arbitrary intersection of closed, connected subsets of a compact space connected?
115272
Showing that projections $\mathbb{R}^2 \to \mathbb{R}$ are not closed