English
InfClosure is closed under SupClosure to yield latticeClosure: infClosure(supClosure s) = latticeClosure s.
Русский
InfClosure сохраняется под SupClosure и даёт latticeClosure: infClosure(supClosure s) = latticeClosure s.
LaTeX
$$$\infClosure(\supClosure(s)) = \mathrm{latticeClosure}(s)$$$
Lean4
protected theorem supClosure (hs : InfClosed s) : InfClosed (supClosure s) :=
by
rintro _ ⟨t, ht, hts, rfl⟩ _ ⟨u, hu, hus, rfl⟩
rw [sup'_inf_sup']
exact finsetSup'_mem_supClosure _ fun i hi ↦ hs (hts (mem_product.1 hi).1) (hus (mem_product.1 hi).2)