English
For every integer n, ZNum.ofInt' n = n (as a ZNum).
Русский
Для каждого целого числа n: ZNum.ofInt' n = n (как ZNum).
LaTeX
$$$$\forall n \in \mathbb{Z},\ ZNum.ofInt' n = n.$$$$
Lean4
@[simp]
theorem ofInt'_eq : ∀ n : ℤ, ZNum.ofInt' n = n
| (n : ℕ) => rfl
| -[n+1] => by
change Num.toZNumNeg (n + 1 : ℕ) = -(n + 1 : ℕ)
rw [← neg_inj, neg_neg, Nat.cast_succ, Num.add_one, Num.zneg_toZNumNeg, Num.toZNum_succ, Nat.cast_succ,
ZNum.add_one]
rfl