proposition: Lemma nrCC4_a9 : z[^]n [=] c or z[^]n [=] [--]c.
proof: Proof. apply nrootCC_2. right. apply ap_wdl_unfolded with b. exact b_. apply eq_reflexive_unfolded. apply nrCC4_a8. apply nrCC4_a7. Qed.
imports: CoRN.complex.CComplex Coq.Arith.Wf_nat Coq.setoid_ring.ArithRing