Definition 17.11.1. Let (X, \mathcal{O}_ X) be a ringed space. Let \mathcal{F} be a sheaf of \mathcal{O}_ X-modules. We say that \mathcal{F} is of finite presentation if for every point x \in X there exists an open neighbourhood x\in U \subset X, and n, m \in \mathbf{N} such that \mathcal{F}|_ U is isomorphic to the cokernel of a map
\bigoplus \nolimits _{j = 1, \ldots , m} \mathcal{O}_ U \longrightarrow \bigoplus \nolimits _{i = 1, \ldots , n} \mathcal{O}_ U
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