English
For W ⊆ V dual space, finite dimensional has equivalence between finiteness of V/W.dualCoannihilator and finiteness of W.
Русский
Для W ⊆ V дуальное пространство, конечномерность V/W.dualCoannihilator эквивалентна конечномерности W.
LaTeX
$$$\\text{FiniteDimensional}(V/W.dualCoannihilator) \\iff \\text{FiniteDimensional}(W)$$$
Lean4
theorem finiteDimensional_quot_dualCoannihilator_iff {W : Submodule K (Dual K V)} :
FiniteDimensional K (V ⧸ W.dualCoannihilator) ↔ FiniteDimensional K W :=
⟨fun _ ↦ FiniteDimensional.of_injective _ W.flip_quotDualCoannihilatorToDual_injective, fun _ ↦
FiniteDimensional.of_injective _ W.quotDualCoannihilatorToDual_injective⟩