English
Let P be a monic polynomial in R[X]. For any ring hom f: R →+* S, the degree of P.map f equals the degree of P.
Русский
Пусть P — мононичный полином над R[X]. Для любого кольцевого гомоморфа f: R →+* S степень( P.map f ) равна степени(P).
LaTeX
$$$\forall {R} {S} [\text{Semiring } R] [\text{Semiring } S] [\text{Nontrivial } S] {P : R[X]} (hmo : P.Monic) (f : R \rightarrow+* S), (P.map f).degree = P.degree$$$
Lean4
@[simp]
theorem degree_map [Semiring S] [Nontrivial S] {P : R[X]} (hmo : P.Monic) (f : R →+* S) : (P.map f).degree = P.degree :=
by simp_all