proposition: Lemma predegE : predeg =1 prelift (fun _ => 1%:Z : int^o).
proof: Proof. move=> D; rewrite /predeg /prelift; apply: eq_bigr. by move=> i _; rewrite /GRing.scale /= mulr1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)