simp [show a = 0 from by simpa using ltx]
case inr
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
ltx : a < 1
⊢ a = 0 ∨ a = 1
no goals