English
In FiniteMultiplicity over a semiring, FiniteMultiplicity p (a + b) implies FiniteMultiplicity p a or FiniteMultiplicity p b.
Русский
Для FiniteMultiplicity в полуприводимой полусложности: FiniteMultiplicity p (a+b) ⇒ FiniteMultiplicity p a или FiniteMultiplicity p b.
LaTeX
$$$\\operatorname{FiniteMultiplicity}(p, a+b) \\Rightarrow \\operatorname{FiniteMultiplicity}(p,a) \\lor \\operatorname{FiniteMultiplicity}(p,b)$$$
Lean4
theorem or_of_add {p a b : α} (hf : FiniteMultiplicity p (a + b)) : FiniteMultiplicity p a ∨ FiniteMultiplicity p b :=
by
by_contra! nh
obtain ⟨c, hc⟩ := hf
simp_all [dvd_add]