proposition: Corollary canword_straightenE w : wcord (straighten w) = canword 's_[w].
proof: Proof. Proof using. rewrite /canword -cocode_straightenE -(wcordE (is_code_straighten w)) //. by rewrite size_straighten. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(fingroup perm morphism presentation) mathcomp(ssralg poly ssrint) permcomp tools permuted combclass congr