English
For any nonzero x in the number field K, the product of the infinite place contributions and the finite place contributions equals 1.
Русский
Для любого не нулевого x в числовом поле K произведение вкладов бесконечных мест и конечных мест даёт 1.
LaTeX
$$$\left(\prod_{w \in \mathrm{InfinitePlace}(K)} w x^{\mathrm{mult}(w)}\right) \cdot \left(\prod_{w \text{ finite place}} w x\right) = 1$$$
Lean4
/-- The Product Formula for the Number Field `K`. -/
theorem prod_abs_eq_one {x : K} (h_x_nezero : x ≠ 0) :
(∏ w : InfinitePlace K, w x ^ w.mult) * ∏ᶠ w : FinitePlace K, w x = 1 := by
simp [prod_eq_inv_abs_norm, InfinitePlace.prod_eq_abs_norm, h_x_nezero]