Lean4
instance normalizedGCDMonoid : NormalizedGCDMonoid PUnit
where
gcd _ _ := unit
lcm _ _ := unit
normUnit _ := 1
normUnit_zero := rfl
normUnit_mul := by subsingleton
normUnit_coe_units := by subsingleton
gcd_dvd_left _ _ := ⟨unit, by subsingleton⟩
gcd_dvd_right _ _ := ⟨unit, by subsingleton⟩
dvd_gcd {_ _} _ _ _ := ⟨unit, by subsingleton⟩
gcd_mul_lcm _ _ := ⟨1, by subsingleton⟩
lcm_zero_left := by subsingleton
lcm_zero_right := by subsingleton
normalize_gcd := by subsingleton
normalize_lcm := by subsingleton