proposition: Lemma eq_big_seq (I : eqType) (r : seq I) F1 F2 : {in r, F1 =1 F2} -> \big[op/idx]_(i <- r) F1 i = \big[op/idx]_(i <- r) F2 i.
proof: Proof. by move=> eqF; rewrite !big_seq (eq_bigr _ eqF). Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div fintype tuple finfun)