Solitons: Differential equations, symmetries, and infinite-dimensional algebras
《Solitons: Differential equations, symmetries, and infinite-dimensional algebras》 · 第 86 页 · Section 3.10「Closed subschemes」
Given a ringed space $(X,\mathcal O_X)$, we call a subsheaf $\mathcal J\subseteq\mathcal O_X$ a sheaf of ideals, if for every open subset $U\subseteq X$ the sections $\Gamma(U,\mathcal J)$ are an ideal in $\Gamma(U,\mathcal O_X)$.