proposition: Lemma big_seq1_id I (i : I) (F : I -> R) : \big[op/x]_(j <- [:: i]) F j = op (F i) x.
proof: Proof. by rewrite big_cons big_nil. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div fintype tuple finfun)