English
The composition of reindexLinearEquiv with itself corresponds to the transitive composition of the index equivalences.
Русский
Сочетание двух reindexLinearEquiv соответствует транспозиции индексов по композиции эквивалентностей.
LaTeX
$$$ (\mathrm{reindexLinearEquiv}\ R\ A e_1' e_2') \;\mathrm{trans} \; (\mathrm{reindexLinearEquiv}\ R\ A e_1 e_2) = \mathrm{reindexLinearEquiv}\ R\ A (e_1.\mathrm{trans} e_1') (e_2.\mathrm{trans} e_2'). $$$
Lean4
theorem reindexLinearEquiv_trans (e₁ : m ≃ m') (e₂ : n ≃ n') (e₁' : m' ≃ m'') (e₂' : n' ≃ n'') :
(reindexLinearEquiv R A e₁ e₂).trans (reindexLinearEquiv R A e₁' e₂') =
(reindexLinearEquiv R A (e₁.trans e₁') (e₂.trans e₂') : _ ≃ₗ[R] _) :=
by
ext
rfl