proposition: Lemma mdomD m1 m2 : finsupp (m1 * m2)%M = finsupp m1 `|` finsupp m2.
proof: Proof. by apply/fsetP=> i; rewrite in_fsetU -!cmE_neq0 cmM addn_eq0 negb_and. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap