∀ (Γ : Type u_1) (R : Type u_2) [inst : AddCancelCommMonoid Γ] [inst_1 : LinearOrder Γ]
  [inst_2 : IsOrderedCancelAddMonoid Γ] [inst_3 : Ring R] [IsDomain R] (x y : HahnSeries Γ R),
  (x * y).orderTop = x.orderTop + y.orderTop