∀ {Γ : Type u_1} {R : Type u_3} [inst : AddCommMonoid Γ] [inst_1 : PartialOrder Γ] [inst_2 : IsOrderedCancelAddMonoid Γ]
  [inst_3 : NonUnitalNonAssocSemiring R] {x y : HahnSeries Γ R}, (x * y).support ⊆ x.support + y.support