English
If R has NoZeroDivisors, then Algebra.IsAlgebraic (MvPolynomial σ R) (MvPolynomial σ S) holds whenever Algebra.IsAlgebraic R S holds.
Русский
Если у R нет нулевых делителей, то Algebra.IsAlgebraic (MvPolynomial σ R) (MvPolynomial σ S) сохраняется при условии Algebra.IsAlgebraic R S.
LaTeX
$$$[NoZeroDivisors\;R] \Rightarrow Algebra.IsAlgebraic(\,MvPolynomial\;σ\;R)(MvPolynomial\;σ\;S)$$$
Lean4
instance {σ} [NoZeroDivisors S] : Algebra.IsAlgebraic (MvPolynomial σ R) (MvPolynomial σ S) :=
by
by_cases h : Function.Injective (algebraMap R S)
· have := h.noZeroDivisors _ (map_zero _) (map_mul _); infer_instance
rw [← MvPolynomial.map_injective_iff] at h
exact Algebra.isAlgebraic_of_not_injective h