proposition: Lemma reduced_rev w : w \is reduced -> rev w \is reduced.
proof: Proof. Proof using. rewrite !unfold_in size_rev => /eqP <-. by rewrite -lengthV -!(big_map nat_of_ord xpredT) -prodsV map_rev revK. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(fingroup perm morphism presentation) mathcomp(ssralg poly ssrint) permcomp tools permuted combclass congr