proposition: Lemma fglift_Freeg s : fglift [freeg s] = prelift s.
proof: Proof. unlock Freeg; unlock fglift; rewrite ?piE /lift. rewrite (prelift_perm_eq (perm_eq_fgrepr _)) /=. exact: prelift_reduce. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)