proposition: Lemma big_distrr I r a (P : pred I) F : a * \big[+%M/0]_(i <- r | P i) F i = \big[+%M/0]_(i <- r | P i) (a * F i).
proof: Proof. by rewrite big_endo ?mulm0 // => x y; apply: mulmDr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div fintype tuple finfun)