English
If M is invertible, then the dual module Dual_R(M) is invertible as an R-module.
Русский
Если M обратим, то дуальный модуль Dual_R(M) является обратимым как R-модуль.
LaTeX
$$Module.Invertible R (Dual_R(M))$$
Lean4
protected theorem right : Module.Invertible R N where
bijective :=
by
rw [show contractLeft R N = ((linearEquivDual e).rTensor N).symm ≪≫ₗ e by
rw [LinearEquiv.coe_trans, LinearEquiv.eq_comp_toLinearMap_symm]; ext; rfl]
apply LinearEquiv.bijective