English
The MonovaryOn relation is symmetric with respect to the pair of functions on a set: swapping the order preserves MonovaryOn.
Русский
Чтобы поменять пары функций на множестве, сохраняется MonovaryOn.
LaTeX
$$$$ \\text{MonovaryOn}(f,g,s) \\iff \\text{MonovaryOn}(g,f,s) $$$$
Lean4
@[symm]
protected theorem symm (h : MonovaryOn f g s) : MonovaryOn g f s := fun _ hi _ hj hf =>
le_of_not_gt fun hg => hf.not_ge <| h hj hi hg