English
A technical identity expressing mulMap under opposites, with opposite linear equivalences and a commutation correction.
Русский
Техническое тождество для mulMap в противоположных структурах, с учетом противоположного линейного эквивалентного отображения и исправления коммутации.
LaTeX
$$$mulMap (equivOpposite.symm (MulOpposite.op M)) (equivOpposite.symm (MulOpposite.op N)) = (MulOpposite.opLinearEquiv R).toLinearMap \circ mulMap N M \circ (TensorProduct.congr (LinearEquiv.ofSubmodule' (MulOpposite.opLinearEquiv R).symm M) (LinearEquiv.ofSubmodule' (MulOpposite.opLinearEquiv R).symm N) \\n ≪≫_l TensorProduct.comm R M N).toLinearMap$$$
Lean4
theorem mulMap_op :
mulMap (equivOpposite.symm (MulOpposite.op M)) (equivOpposite.symm (MulOpposite.op N)) =
(MulOpposite.opLinearEquiv R).toLinearMap ∘ₗ
mulMap N M ∘ₗ
(TensorProduct.congr (LinearEquiv.ofSubmodule' (MulOpposite.opLinearEquiv R).symm M)
(LinearEquiv.ofSubmodule' (MulOpposite.opLinearEquiv R).symm N) ≪≫ₗ
TensorProduct.comm R M N).toLinearMap :=
TensorProduct.ext' fun _ _ ↦ rfl