proposition: Lemma malgMEw (d1 d2 : {fset K}) g1 g2 : msupp g1 `<=` d1 -> msupp g2 `<=` d2 -> g1 * g2 = \sum_(k1 <- d1) \sum_(k2 <- d2) << g1@_k1 * g2@_k2 *g k1 * k2 >>.
proof: Proof. exact/fgmullw. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap