English
Let L, L' be Lie algebras over a commutative ring R, and f: L → L' be injective. If L' is nilpotent, then L is nilpotent.
Русский
Пусть L, L' — алгебры Ли над коммутативным кольцом R, и f: L → L' — инъективное отображение. Если L' нильпотентна, то и L нильпотентна.
LaTeX
$$$(\text{Injective } f) \land (\text{IsNilpotent } L') \Rightarrow \text{IsNilpotent } L$$$
Lean4
theorem lieAlgebra_isNilpotent [h₁ : IsNilpotent L'] {f : L →ₗ⁅R⁆ L'} (h₂ : Function.Injective f) : IsNilpotent L :=
by
rw [LieRing.IsNilpotent, LieModule.isNilpotent_iff R] at h₁ ⊢
peel h₁ with k hk
apply LieIdeal.bot_of_map_eq_bot h₂; rw [eq_bot_iff, ← hk]
apply LieIdeal.map_lowerCentralSeries_le