English
Let ϕ: L →ₐ[K] L be a K-algebra homomorphism with [FiniteDimensional K L]. Then ϕ is bijective.
Русский
Пусть ϕ: L →ₐ[K] L — алгебраический гомоморфизм с [FiniteDimensional K L]. Тогда ϕ биективен.
LaTeX
$$$[FiniteDimensional K L]\Rightarrow (\forall ϕ: L →ₐ[K] L, Function.Bijective\ ϕ)$$$
Lean4
protected theorem neg : IsAlgebraic R (-a) :=
have ⟨p, h, eval0⟩ := ha
⟨algEquivAevalNegX p, EmbeddingLike.map_ne_zero_iff.mpr h, by simpa [← comp_eq_aeval, aeval_comp]⟩