Let $(X,\tau)$ be a topological space, $S\subseteq X$ such that there is $x^*\in X\setminus S$.

Let $E$ be the connected component of $X\setminus S$ that contains $x^*$. Let ${\cal C}$ be the collection of connected components of $S$. For each $C\in {\cal C}$ let $E_C$ be the connected component of $X\setminus C$ that contains $x^*$.

Do we have $E=\bigcap\{E_C: C\in{\cal C}\}$?


1 Answer 1


Let $X$ be the circle $S^1$ in $\mathbb C$ and let $S$ be the set $\{1,-1\}$. Let $x^*=i$ then $E$ is the intersection of $X$ with the upper half plane but the intersection of the $E_C$ also contains point in the lower half plane.


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