proposition: Theorem ps_add_assoc : ∀ ps₁ ps₂ ps₃, (ps₁ + (ps₂ + ps₃) = (ps₁ + ps₂) + ps₃)%ps.
proof: Proof. intros ps₁ ps₂ ps₃; symmetry. constructor. apply ps_normal_add_assoc. Qed.
imports: Utf8 QArith NPeano NbarM Misc Field2 Power_series Puiseux_series