English
For a principal span of s, r divides the generator of span s iff r divides every x in s.
Русский
Для главного окна порождения span s, r делит генератор span s тогда и только тогда, когда r делит каждый элемент x ∈ s.
LaTeX
$$r ∣ generator (Ideal.span s) ↔ ∀ x ∈ s, r ∣ x$$
Lean4
theorem prime_generator_of_isPrime (S : Ideal R) [S.IsPrincipal] [is_prime : S.IsPrime] (ne_bot : S ≠ ⊥) :
Prime (generator S) :=
⟨fun h => ne_bot ((eq_bot_iff_generator_eq_zero S).2 h), fun h =>
is_prime.ne_top (S.eq_top_of_isUnit_mem (generator_mem S) h), fun _ _ => by
simpa only [← mem_iff_generator_dvd S] using is_prime.2⟩
-- Note that the converse may not hold if `ϕ` is not injective.