case pos
n : ℕ
R : Type u_1
inst✝ : Ring R
hzero : n = 0
⊢ map (Int.castRingHom R) (cyclotomic n ℤ) = cyclotomic n R

case neg
n : ℕ
R : Type u_1
inst✝ : Ring R
hzero : ¬n = 0
⊢ map (Int.castRingHom R) (cyclotomic n ℤ) = cyclotomic n R
n : ℕ
R : Type u_1
inst✝ : Ring R
⊢ map (Int.castRingHom R) (cyclotomic n ℤ) = cyclotomic n R
by_cases hzero : n = 0
no goals
case neg
n : ℕ
R : Type u_1
inst✝ : Ring R
hzero : ¬n = 0
⊢ map (Int.castRingHom R) (cyclotomic n ℤ) = cyclotomic n R
simp [cyclotomic, hzero]
no goals
case pos
n : ℕ
R : Type u_1
inst✝ : Ring R
hzero : n = 0
⊢ map (Int.castRingHom R) (cyclotomic n ℤ) = cyclotomic n R
simp only [hzero, cyclotomic, dif_pos, Polynomial.map_one]