For a subset $A$ of a metric space which of the following implies the other three ?
$a)$ $A$ is closed
$b)$ $A$ is bounded
$c)$Closure of $B$ is compact ,for every $B \subseteq A$
$d)$ $A$ is compact
I thinks option d) will correct .
is it true??
Best Answer
(d) is right, as a compact set is closed and bounded in any metric space. and also if $A$ is compact then for $B \subseteq A$, $\overline{B}$ is closed in $\overline{A}=A$ and hence compact too.