proposition: Lemma eq_big_op_seq : forall (I : eqType) r (P : pred I) F, (forall i, P i && (i \in r) -> Pb (F i)) -> \big[op1/idx]_(i <- r | P i) F i === \big[op2/idx]_(i <- r | P i) F i.
proof: Proof. move=> I r P F Pb_F; rewrite -> big_cond_seq. by symmetry; rewrite -> big_cond_seq; symmetry; apply eq_big_op. Qed.
imports: ssreflect ssrbool ssrfun eqtype ssrnat seq div choice fintype finfun paths Setoid Morphisms OperationClasses bigops