English
For p prime and n, the polynomial map of Frobenius relates to the Witt polynomial with index n via a polynomial map over ℚ.
Русский
При p простом и n, полином Frobenius связан с Witt-полином индексом n через полином по коэффициентам над ℚ.
LaTeX
$$$\forall (p,n),\; \text{map}_{\mathbb{Q}}(\operatorname{frobeniusPoly}(p,n)) = \operatorname{...}.$$$
Lean4
theorem frobeniusPoly_zmod (n : ℕ) : MvPolynomial.map (Int.castRingHom (ZMod p)) (frobeniusPoly p n) = X n ^ p :=
by
rw [frobeniusPoly, RingHom.map_add, RingHom.map_pow, RingHom.map_mul, map_X, map_C]
simp only [Int.cast_natCast, add_zero, eq_intCast, ZMod.natCast_self, zero_mul, C_0]