English
The length of a module is defined as the Krull dimension of its submodule lattice (lifted to ENat).
Русский
Длина модуля определяется как крулль-измерение решетки подмодулов (в виде ENat).
LaTeX
$$$\operatorname{length}(R,M) = \operatorname{unbot}(\operatorname{krullDim}(\operatorname{Submodule}_R M)).$$$
Lean4
/-- The length of a module, defined as the krull dimension of its submodule lattice. -/
noncomputable def length : ℕ∞ :=
(Order.krullDim (Submodule R M)).unbot (by simp [Order.krullDim_eq_bot_iff])