proposition: Lemma freegUB k1 k2 x : << k1 *g x >> - << k2 *g x >> = << (k1-k2) *g x >>.
proof: Proof. by rewrite freegUN freegUD. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)