Can any space be seen as the boundary of some other space?
95897
Which sets occur as boundaries of other sets in topological spaces?
137438
Restrict a metric, gives same topology as subspace topology from larger space $X$
68234
Is $[0,1) \cup \{2\}$ a manifold with boundary? My issue is the $2$.
151358
Continuous image of a locally connected space which is not locally connected
57122
If $E$ is a connected space, then so is $\overline{E}$.
104940
Are infinite reflections between two mirrors really infinite?
7794
Can a non-Euclidean space be descripted through an Euclidean space of higher dimension? So why use non-Euclidean?
15799
Experimental evidence of a fourth spatial dimension?
149777
Is it true that a space-filling curve cannot be injective everywhere?
47056
Show that the boundary of a set equals the boundary of its complement
126744
Is any Banach space a dual space?
158850
Is it true that a boundary of a simply connected and bounded set is connected in $\mathbb{C}$?
25827
Does time expand with space? (or contract)
41997
Can the boundary of a set be ignored, when integrating over it.
66880
Seeking neighborhood boundaries globally?
10733
Seeking administrative boundaries for various countries?
48344
What does a space mean?