proposition: Lemma qX_order_dvd (i : nat) : 'qX ^+ i = 1 :> qT -> (#|qT|.-1 %| i)%N.
proof: Proof. rewrite -gX_order cyclic.order_dvdn => Hd. by apply/eqP/val_inj; rewrite /= -Hd val_unitX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice fintype tuple) mathcomp(div bigop binomial finset finfun ssralg countalg finalg) mathcomp(poly polydiv qpoly perm fingroup falgebra fieldext finfield galois) mathcomp(finalg zmodp matrix vector)