English
For t and t' subsets of PrimeSpectrum(R), the sup of their vanishing ideals is contained in the vanishing ideal of their intersection:
Русский
Для подмножеств t и t' PrimeSpectrum(R) верхняя граница (объединение) их ванishing ideals включена в ванishingIdeal пересечения:
LaTeX
$$$\\mathrm{vanishingIdeal}(t) \\sqcup \\mathrm{vanishingIdeal}(t') \\leq \\mathrm{vanishingIdeal}(t \\cap t').$$$
Lean4
theorem sup_vanishingIdeal_le (t t' : Set (PrimeSpectrum R)) :
vanishingIdeal t ⊔ vanishingIdeal t' ≤ vanishingIdeal (t ∩ t') :=
by
intro r
rw [Submodule.mem_sup, mem_vanishingIdeal]
rintro ⟨f, hf, g, hg, rfl⟩ x ⟨hxt, hxt'⟩
rw [mem_vanishingIdeal] at hf hg
apply Submodule.add_mem <;> solve_by_elim