定义: 

概型是指某个 ringed space $X,\mathcal{O}_X$, $X$ 中每个点存在一个邻域 $U$ 使得 ringed space $U,\mathcal{O}_{X}|_U$ 同构于某个环 $A$ 的 $\mathrm{Spec}A$.

A scheme is a ringed space $X,\mathcal{O}_X$ for which every point has a neighbourhood $U$ such that the ringed space $U,\mathcal{O}_{X}|_U$ is isomorphic to $\mathrm{Spec}A$, where $A$ is some ring.

参见 [1] P.28

References:

[1] Shafarevich, Basic Algebraic Geometry 2.