Solution
= Solution
In the usual <real line>, take $\boxed{F_n=[n,\infty)}$ for $n\geq1$. The sets are closed, nonempty and nested, but no real number belongs to all of them.
= Solution
In the usual <real line>, take $\boxed{F_n=[n,\infty)}$ for $n\geq1$. The sets are closed, nonempty and nested, but no real number belongs to all of them.