proposition: Theorem ps_add_comm : ∀ ps₁ ps₂, (ps₁ + ps₂ = ps₂ + ps₁)%ps.
proof: Proof. intros ps₁ ps₂. constructor. rewrite eq_strong_ps_add_comm; reflexivity. Qed.
imports: Utf8 QArith NPeano NbarM Misc Field2 Power_series Puiseux_series