no goals
α : Type u
inst✝² : Group α
inst✝¹ : LT α
inst✝ : CovariantClass α α (swap fun x x_1 => x * x_1) fun x x_1 => x < x_1
a b c : α
⊢ a * b⁻¹ < 1 ↔ a < b
rw [← mul_lt_mul_iff_right b, inv_mul_cancel_right, one_mul]