English
Product of a multiset of elements in a subring of a commutative ring is in the subring.
Русский
Произведение мультисета элементов в подполье подп кольца в комм кольце принадлежит подполью.
LaTeX
$$$\\forall R\\, [\\text{CommRing }R]\\, (s: Subring R)\\, (m: Multiset R),\\ (\\forall a \\in m, a \\in s) \\Rightarrow m.prod \\in s.$$$
Lean4
/-- Product of a multiset of elements in a subring of a `CommRing` is in the subring. -/
protected theorem multiset_prod_mem {R} [CommRing R] (s : Subring R) (m : Multiset R) : (∀ a ∈ m, a ∈ s) → m.prod ∈ s :=
multiset_prod_mem _