∀ {R : Type u_1} (M : Type u_3) [inst : CommRing R] [inst_1 : AddCommGroup M] [inst_2 : Module R M] (r : R)
  (rs : List R),
  RingTheory.Sequence.IsRegular M (r :: rs) = (IsSMulRegular M r ∧ RingTheory.Sequence.IsRegular (QuotSMulTop r M) rs)