proposition: Lemma msuppD_le g1 g2 : msupp (g1 + g2) `<=` msupp g1 `|` msupp g2.
proof: Proof. apply/fsubsetP=> k; rewrite in_fsetU -mcoeff_neq0 mcoeffD. by case: (msuppP g1); case: (msuppP g2); rewrite //= addr0 eqxx. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap