English
For finite s ⊆ α and t ⊆ β and g: γ → δ, the infimum over image₂ f s t equals the iterated infimum: inf over x∈s of inf over y∈t of g(f(x,y)).
Русский
Для конечных s ⊆ α и t ⊆ β и g: γ → δ, инфimum по image₂ f s t равен повторному инфимумиуму: inf_{x∈s} inf_{y∈t} g(f(x,y)).
LaTeX
$$$\inf (\operatorname{image}_2 f s t) g = \inf_{x \in s} \inf_{y \in t} g(f x y)$$$
Lean4
theorem inf_image₂_left (g : γ → δ) : inf (image₂ f s t) g = inf s fun x ↦ inf t (g ∘ f x) :=
sup_image₂_left (δ := δᵒᵈ) ..