English
The set { f : β → α | Monotone f } is closed in the space of all functions β → α with the order-closed topology on α.
Русский
Множество функций { f : β → α | Monotone f } замкнуто в пространстве всех функций β → α при топологии порядка на α.
LaTeX
$$$ \\text{IsClosed} \\{ f:\\beta \\to \\alpha \\mid \\text{Monotone } f \\} $$$
Lean4
/-- The set of monotone functions is closed. -/
theorem isClosed_monotone [Preorder β] : IsClosed {f : β → α | Monotone f} :=
by
simp_rw [← monotoneOn_univ]
exact isClosed_monotoneOn