English
If every element of a multiset m lies in a Subsemiring s of a commutative semiring, then the product of all elements of m lies in s.
Русский
Если каждый элемент мультисовета m принадлежит Subsemiring s ⊆ R, то произведение всех элементов m принадлежит s.
LaTeX
$${m : Multiset R} → (∀ a ∈ m, a ∈ s) → m.prod ∈ s$$
Lean4
/-- Product of a multiset of elements in a `Subsemiring` of a `CommSemiring`
is in the `Subsemiring`. -/
protected theorem multiset_prod_mem {R} [CommSemiring R] (s : Subsemiring R) (m : Multiset R) :
(∀ a ∈ m, a ∈ s) → m.prod ∈ s :=
multiset_prod_mem m