proposition: Lemma invCi : 'i^-1 = - 'i :> C.
proof: Proof. by rewrite -div1r -[1]opprK -sqrCi mulNr mulfK ?neq0Ci. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)