English
Under faithful flatness of A, the solvability of A ⊗_R L is equivalent to the solvability of L.
Русский
При условии полной плоскости A как модуль над R существование равенства: solvable(A ⊗_R L) ⇔ solvable(L).
LaTeX
$$$\text{IsSolvable} (A \otimes_R L) \;\iff\; \text{IsSolvable } L$$$
Lean4
theorem isSolvable_tensorProduct_iff : IsSolvable (A ⊗[R] L) ↔ IsSolvable L :=
by
refine ⟨?_, fun _ ↦ inferInstance⟩
rw [isSolvable_iff A, isSolvable_iff R]
rintro ⟨k, h⟩
use k
rw [eq_bot_iff] at h ⊢
intro x hx
rw [derivedSeries_baseChange] at h
specialize h <| Submodule.tmul_mem_baseChange_of_mem 1 hx
rw [LieSubmodule.mem_bot] at h ⊢
rwa [Module.FaithfullyFlat.one_tmul_eq_zero_iff] at h