Solitons: Differential equations, symmetries, and infinite-dimensional algebras
《Solitons: Differential equations, symmetries, and infinite-dimensional algebras》 · 第 406 页 · Proposition and Definition 13.78(1)
A qcqs scheme $X$ is called quasi-affine if the following equivalent properties are satisfied: (i) There exists an open embedding $X\hookrightarrow Y$ into an affine scheme $Y$. (ii) The structure sheaf $\mathcal O_X$ is ample. (iii) Every invertible $\mathcal O_X$-module is ample.