English
The grade map is monotone with respect to the base order: a ≤ b implies grade(a) ≤ grade(b).
Русский
Функция града монотонна по базовому порядку: a ≤ b ⇒ grade(a) ≤ grade(b).
LaTeX
$$$a \le b \Rightarrow \mathrm{grade}(a) \le \mathrm{grade}(b).$$$
Lean4
theorem grade_mono [PartialOrder α] [GradeOrder 𝕆 α] : Monotone (grade 𝕆 : α → 𝕆) :=
grade_strictMono.monotone