proposition: Lemma malgME g1 g2 : g1 * g2 = \sum_(k1 <- msupp g1) \sum_(k2 <- msupp g2) << g1@_k1 * g2@_k2 *g k1 * k2 >>.
proof: Proof. by []. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap