English
The principal-equivalence is a monoid hom: the image of a product equals the product of the images.
Русский
Главное эквивалентное отображение сохраняет произведение: образ произведения равен произведению образов.
LaTeX
$$$(associatesNonZeroDivisorsEquivIsPrincipal\ R (x * y) : Ideal R) = (associatesNonZeroDivisorsEquivIsPrincipal\ R x) * (associatesNonZeroDivisorsEquivIsPrincipal\ R y)$$$
Lean4
theorem associatesNonZeroDivisorsEquivIsPrincipal_mul (x y : Associates R⁰) :
(associatesNonZeroDivisorsEquivIsPrincipal R (x * y) : Ideal R) =
(associatesNonZeroDivisorsEquivIsPrincipal R x) * (associatesNonZeroDivisorsEquivIsPrincipal R y) :=
by simp_rw [associatesNonZeroDivisorsEquivIsPrincipal_coe, map_mul, Submonoid.coe_mul, associatesEquivIsPrincipal_mul]