English
For any natural x, (x : R) = 0 iff ringChar R divides x.
Русский
Для любого x ∈ ℕ, x в R равен нулю тогда и только тогда, когда ringChar R делит x.
LaTeX
$$$\forall x \in \mathbb{N}, \ (x : R) = 0 \iff \operatorname{ringChar}(R) \mid x.$$$
Lean4
theorem spec : ∀ x : ℕ, (x : R) = 0 ↔ ringChar R ∣ x :=
by
letI : CharP R (ringChar R) := (Classical.choose_spec (CharP.existsUnique R)).1
exact CharP.cast_eq_zero_iff R (ringChar R)