These observations allow one to formalize the definition of reflection: a reflection is an involutive isometry of an Euclidean space whose set of fixed points is an affine subspace of codimension 1.
这些观察允许我们形射的定义:
射
欧几里得空
的对
等距同构,它的不动点
余维度为 1 的仿射子空
。