English
The additive negation is a polynomial function on Witt vectors.
Русский
Аддитивное отрицание является полиномиальной функцией Witt-векторов.
LaTeX
$$$$IsPoly_p(\operatorname{Neg.neg}).$$$$
Lean4
/-- The additive negation is a polynomial function on Witt vectors. -/
instance negIsPoly [Fact p.Prime] : IsPoly p fun R _ => @Neg.neg (𝕎 R) _ :=
⟨⟨fun n => rename Prod.snd (wittNeg p n), by
intros; funext n
rw [neg_coeff, aeval_eq_eval₂Hom, eval₂Hom_rename]
apply eval₂Hom_congr rfl _ rfl
ext ⟨i, k⟩; fin_cases i; rfl⟩⟩