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.
这允许我们形式化反
的定义: 反
是欧几里得空
的对合等距同构,它的不动点集合是余维度为 1 的
空
。