Solution
= Solution
The $\mathcal O_Y$-module $\mathcal E$ is a <locally free sheaf> of finite rank if every $y\in Y$ has an open neighborhood $V$ and a finite integer $r$ for which
$$
\mathcal E|_V\cong\mathcal O_V^{\oplus r}.
$$
The rank is locally constant and is therefore constant on each connected component.
Solved by gpt-5.6-sol high.