Let $A$ be a nonempty open connected subset of a (real) topological vector space $X$.
Question. Is it true that there exists a nonempty open connected set $B\subseteq A$ such that $B$, in addition, is symmetric (i.e., $B=-B$)?
Let $A$ be a nonempty open connected subset of a (real) topological vector space $X$.
Question. Is it true that there exists a nonempty open connected set $B\subseteq A$ such that $B$, in addition, is symmetric (i.e., $B=-B$)?
$(0,1)$ is a nonempty open connected subset of $\mathbb R$ and it does not contain any nonempty symmetric set.