Let $(X,\tau)$ be a topological space. We say ${\cal U}\subseteq \tau$ is an open cover if 

- $\bigcup {\cal U} = X$, and
- $X\notin {\cal U}$.

${\cal U}$ is *minimal* if for all $U_0\in {\cal U}$ we have $\bigcup ({\cal U}\setminus \{U_0\}) \neq X$. Clearly, every $T_1$-space on more than $1$ point possesses a minimal cover: pick $x\neq y\in X$ and let ${\cal U} = \{X\setminus\{x\}, X\setminus\{y\}\}$.

**Question.** Given any open cover of a Hausdorff space $(X,\tau)$ with $|X|>1$, does it have a [refinement](https://en.wikipedia.org/wiki/Cover_(topology)#Refinement) that is a minimal cover? 

**Note.** I didn't ask for subcovers in the question above: Let $X = \mathbb{R}$ with the Euclidean topology, then ${\cal U} = \big\{ \{x\in\mathbb{R}: x < n\} : n\in\mathbb{N}, n\geq 1 \big\}$ does not have a minimal subcover.