English
Given an injective g and a composition equality, Transcendental S (g a) is equivalent to Transcendental R a.
Русский
При инъективности g и равенстве композиции Transcendental(S, g(a)) эквивалентно Transcendental(R, a).
LaTeX
$$$\text{Transcendental}(S, g(a)) \iff \text{Transcendental}(R, a)$$$
Lean4
theorem isAlgebraic_ringHom_iff_of_comp_eq (h : RingHom.comp (algebraMap S B) f = RingHom.comp g (algebraMap R A)) :
Algebra.IsAlgebraic S B ↔ Algebra.IsAlgebraic R A :=
⟨fun H ↦ H.of_ringHom_of_comp_eq f g (EquivLike.surjective f) (EquivLike.injective g) h, fun H ↦
H.ringHom_of_comp_eq f g (EquivLike.injective f) (EquivLike.surjective g) h⟩