apply False.elim
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n✝ m n : ℕ
x✝ : step n + m ≃ 0
⊢ step n ≃ 0 ∧ m ≃ 0
case h
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n✝ m n : ℕ
x✝ : step n + m ≃ 0
⊢ False