English
The pair of maps setOfIdeal and idealOfSet forms a Galois connection between subsets of X and ideals of C(X,R): for any I and s, s ⊆ setOfIdeal(I) iff I ⊆ idealOfSet(R,s).
Русский
Парa отображений setOfIdeal и idealOfSet образует связь Гalas между подмножествами X и идеалами C(X,R): для любых I и s выполняется s ⊆ setOfIdeal(I) эквивалентно I ⊆ idealOfSet(R,s).
LaTeX
$$$ \\text{GaloisConnection}(setOfIdeal, idealOfSet(R,\\cdot)) $$$
Lean4
theorem notMem_setOfIdeal {I : Ideal C(X, R)} {x : X} : x ∉ setOfIdeal I ↔ ∀ ⦃f : C(X, R)⦄, f ∈ I → f x = 0 := by
rw [← Set.mem_compl_iff, setOfIdeal, compl_compl, Set.mem_setOf]