English
Regular M of a cons is equivalent to the conjoined regularity of its head and the regularity of its tail in the quotient.
Русский
Регулярность cons-структуры равна объединённой регулярности головы и регулярности хвоста в фактор-модуле.
LaTeX
$$$IsRegular(M, rs) \\iff IsSMulRegular(M, r) \\land IsRegular(QuotSMulTop r M, rs)$$$
Lean4
@[simp]
theorem isRegular_cons_iff (r : R) (rs : List R) :
IsRegular M (r :: rs) ↔ IsSMulRegular M r ∧ IsRegular (QuotSMulTop r M) rs := by
rw [isRegular_iff, isRegular_iff, isWeaklyRegular_cons_iff M r rs, ne_eq, top_eq_ofList_cons_smul_iff, and_assoc]