English
Regular M (r :: rs) is equivalent to the conjunction of regularity of r and regularity on the quotient with rs mapped accordingly.
Русский
Регулярность M (r :: rs) эквивалентна сочетанию регулярности r и регулярности на фактор-модуле.
LaTeX
$$$IsRegular(M, r :: rs) \\iff IsSMulRegular(M, r) \\land IsRegular(QuotSMulTop r M, rs.map (Ideal.Quotient.mk (Ideal.span { r }))) rs$$$
Lean4
theorem cons {r : R} {rs : List R} (h1 : IsSMulRegular M r) (h2 : IsRegular (QuotSMulTop r M) rs) :
IsRegular M (r :: rs) :=
(isRegular_cons_iff M r rs).mpr ⟨h1, h2⟩