rintro (rfl | rfl | rfl | rfl) <;> simp [one_le_two, ←two_add_one_eq_three]
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐏𝐀⁻
a b c : M
⊢ a = 0 ∨ a = 1 ∨ a = 2 ∨ a = 3 → a ≤ 3
no goals