English
If the family {H_i} is iSupIndep (a strong independence condition), then the canonical homomorphism from the product of subgroups to G is injective.
Русский
Если семейство {H_i} удовлетворяет условию iSupIndep (сильная независимость), то канонический копродуктовый гомоморфизм инъективен.
LaTeX
$$$\ker(\text{noncommPiCoprod } hcomm) = \{1\}$ under hind$$
Lean4
@[to_additive]
theorem injective_noncommPiCoprod_of_iSupIndep
{hcomm : Pairwise fun i j : ι => ∀ x y : G, x ∈ H i → y ∈ H j → Commute x y} (hind : iSupIndep H) :
Function.Injective (noncommPiCoprod hcomm) :=
by
apply MonoidHom.injective_noncommPiCoprod_of_iSupIndep
· simpa using hind
· intro i
exact Subtype.coe_injective