Solitons: Differential equations, symmetries, and infinite-dimensional algebras
《Solitons: Differential equations, symmetries, and infinite-dimensional algebras》 · 第 141 页 · Definition 5.58
A plane curve is a closed subscheme $C$ of $\mathbb P^2_k$ that is of the form $V_+(f)$, where $0\ne f\in k[X,Y,T]$ is a non-constant homogeneous polynomial.