$\newcommand{\cl}{\operatorname{cl}}\newcommand{\int}{\operatorname{int}}$So there’s another excercise I’ve been struggling with recently, very similar to the previous one.
Let $A$ be a subset of topological space $X$ and:
$B:=X\setminus\cl\int A$.
Prove that $B=\int\cl B$.
I’ve got the first part, that left side is included in the right side, what was pretty obvious. Harder part is proving second inclusion. Any ideas? Also, have you got any good excercises books or something like that, because I definetly need some training and in my book there aren’t much excercises.
