proposition: Lemma fgmulg0 : right_zero 0 fgmul.
proof: Proof. by move=> g; rewrite fgmulr msupp0 big_seq_fset0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap