English
If f is monotone in the first argument and antitone in the second, then image2 f (upperBounds s) (lowerBounds t) is contained in lowerBounds (image2 f s t).
Русский
Если f монотонна по первому аргументу и антимонотонна по второму, то image2 f (upperBounds s) (lowerBounds t) ⊆ lowerBounds (image2 f s t).
LaTeX
$$ (∀ (b), Antitone (swap f b)) → (∀ a, Monotone (f a)) → image2 f (upperBounds s) (lowerBounds t) ⊆ lowerBounds (image2 f s t)$$
Lean4
theorem image2_upperBounds_lowerBounds_subset_lowerBounds_image2 :
image2 f (upperBounds s) (lowerBounds t) ⊆ lowerBounds (image2 f s t) :=
image2_subset_iff.2 fun _ ha _ hb ↦ mem_lowerBounds_image2_of_mem_lowerBounds_of_mem_lowerBounds h₀ h₁ ha hb