Is every semi-stratifiable space $\omega$-monolithic? --- ## Definitions A topological space $(X,\tau)$ is called **semi-stratifiable** if there exists a function $g:\omega\times X\to\tau$ such that: 1. for any point $x$ of $X$ holds $\{x\}=\bigcap_{n\in\omega} g(n,x)$; 2. for any point $x$ of $X$ and a sequence $\{x_n\}$ of $X$, if $x \in g(n,x_n)$ for each $n$, then $x_n \to x$. A topological space $X$ is said to be **$\omega$-monolithic** if $nw(\overline{A}) \le \omega$ for any subset $A \subset X$ with $|A| \le \omega$. $nw(X)=\min\{|\mathcal N|: \mathcal N \text{ is a net for } X\}+\omega$. If not. What if $X$ is semi-metric space? Note that $X$ is semi-metric iff $X$ is first and semi-stratifiable;