English
Let α be a type with zero and a natural three, and assume 3 ≠ 0. Then 3 ≠ 0.
Русский
Пусть α — множество с нулём и элементом, соответствующим числу 3, и предположим, что 3 ≠ 0. Тогда 3 ≠ 0.
LaTeX
$$$3 \neq 0$$$
Lean4
/-- If `M` is an `R`-module with one and `M` has characteristic zero, then `R` has characteristic
zero as well. Usually `M` is an `R`-algebra. -/
theorem of_module (M) [AddCommMonoidWithOne M] [CharZero M] [Module R M] : CharZero R :=
by
refine ⟨fun m n h => @Nat.cast_injective M _ _ _ _ ?_⟩
rw [← nsmul_one, ← nsmul_one, ← Nat.cast_smul_eq_nsmul R, ← Nat.cast_smul_eq_nsmul R, h]