proposition: Lemma PrefreegK rD : Prefreeg rD = rD %[mod_eq (@fgequiv G K)].
proof: Proof. exact/eqmodP/reduceK/prefreeg_reduced. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)