English
A strictly monotone function on a cowell-order satisfies f ≤ id; i.e., f reversely bounded by identity.
Русский
Строго монотонная функция на обратном порядке удовлетворяет f ≤ id.
LaTeX
$$$\\text{StrictMono } f \\Rightarrow f \\leq \\mathrm{id}$ на cowell-order β$$
Lean4
/-- A strictly monotone function `f` on a cowell-order satisfies `f x ≤ x` for all `x`. -/
theorem le_id [WellFoundedGT β] {f : β → β} (hf : StrictMono f) : f ≤ id :=
StrictMono.id_le (β := βᵒᵈ) hf.dual