proposition: Lemma rootC0 n : n.-root 0 = 0.
proof: Proof. have [-> | n_gt0] := posnP n; first by rewrite root0C. by have /eqP := rootCK n_gt0 0; rewrite expf_eq0 n_gt0 /= => /eqP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)