Tangent space of open set
15596
Identification of each tangent space $T_pV$ with $V$ itself?
135454
An open interval is an open set?
73130
A simple question about open set
15645
Is convex open set in $\mathbb{R}^n$ is regular?
12349
a construction of a continuous function from a normal space to [0,1]
152193
The intersection of a closure with an open set
84104
Definition of neighborhood and open set in topology
82825
Proving set of interiors is open
153767
Singular points and tangent lines
15487
Continuous function from a connected set?
63442
Show that if $U$ is an open connected subspace of $\mathbb{R}^2$, then $U$ is path connected
129081
Proof that convex open sets in $\mathbb{R}^n$ are homeomorphic?
81351
Polish space in which the interior of each compact set is empty
47992
Is there a function $f\colon\mathbb{R}\to\mathbb{R}$ such that every non-empty open interval is mapped onto $\mathbb{R}$?
44704
familly of Radially open sets in $\mathbb{R}^2$
128410
Showing that the set of fixed points is a smooth manifold
48557
Product of connected spaces