If $U\subset \mathbb{R^n}$ is open then $\dim U=n?$
75829
Dimension of open subsets of $R^n$
73927
Is $\mathbb{R}$ a subset of $\mathbb{R}^2$?
44704
familly of Radially open sets in $\mathbb{R}^2$
59424
Showing that $B=\{(x,y) \in \Bbb{R^2} \mid \ xy>0 \}$ is an open set
130297
$A$ be a subset of $[0,1]$ with non-empty interior ; then is it true that $\mathbb Q+A=\mathbb R$?
43504
Proving the existence of a complement subspace $U' \subset V$.
73130
A simple question about open set
102168
Prove that there exists disjoint open subsets $U,V$ of $X$ such that $x \in U$ and $B \subseteq V$.
13066
A Zariski open subset of a variety has the same dimension as the variety.
2575
Showing that $\mathbb{R}$ is connected
129081
Proof that convex open sets in $\mathbb{R}^n$ are homeomorphic?
2198
Maps from subsets of $\mathbb{R}^2$ that are either open/closed/continuous
82464
$U^*\otimes V$ versus $L(U,V)$ for infinite dimensional spaces
60053
Does the boundary of an open set have measure zero (in $\mathbb{R}^n$)?
127575
Prove that Open Sets in $\mathbb{R}$ are The Disjoint Union of Open Intervals Without the Axioms of Choice
92639
Prove that the family of open sets in $\mathbb{R}$ has cardinality equal to $2^{\aleph_0}$
107160
Open Set and Measure Theory