English
If s and t have infs, then truncatedInf (s ⊼ t) a equals truncatedInf s a ⊓ truncatedInf t a.
Русский
Если существуют inf' для s и t, то truncatedInf(s ⊼ t) a = truncatedInf s a ⊓ truncatedInf t a.
LaTeX
$$$\operatorname{truncatedInf}(s \sqcap t) \, a = \operatorname{truncatedInf} s \, a \sqcap \operatorname{truncatedInf} t \, a$$$
Lean4
theorem truncatedInf_sups (hs : a ∈ upperClosure s) (ht : a ∈ upperClosure t) :
truncatedInf (s ⊻ t) a = truncatedInf s a ⊔ truncatedInf t a :=
by
simp only [truncatedInf_of_mem, hs, ht, sups_aux.2 ⟨hs, ht⟩, inf'_sup_inf', filter_sups_le]
simp_rw [← image_sup_product]
rw [inf'_image]
simp [Function.uncurry_def]