English
For algebra equivalences e: A1 ≃ₐ[R] A2 and f: A2 ≃ₐ[R] A3, the map on mv-polynomials respects composition, i.e., (mapAlgEquiv σ e).trans (mapAlgEquiv σ f) = mapAlgEquiv σ (e.trans f).
Русский
Для алгебраических эквивалентностей e: A1 ≃ₐ[R] A2 и f: A2 ≃ₐ[R] A3 отображение mv-многочленов сохраняет композицию, то есть (mapAlgEquiv σ e).trans (mapAlgEquiv σ f) = mapAlgEquiv σ (e.trans f).
LaTeX
$$$$ (mapAlgEquiv \\; σ\\; e).trans (mapAlgEquiv \\; σ\\; f) = mapAlgEquiv \\; σ\\; (e.trans f). $$$$
Lean4
@[simp]
theorem mapAlgEquiv_trans (e : A₁ ≃ₐ[R] A₂) (f : A₂ ≃ₐ[R] A₃) :
(mapAlgEquiv σ e).trans (mapAlgEquiv σ f) = mapAlgEquiv σ (e.trans f) :=
by
ext
simp only [AlgEquiv.trans_apply, mapAlgEquiv_apply, map_map]
rfl