have : compare n m = Ordering.eq := ord_sgn_inject this
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
x✝ : (n——m).sgn ≃ 0
this✝ : ord_sgn (compare n m) ≃ 0
this : ord_sgn (compare n m) ≃ ord_sgn Ordering.eq
⊢ n——m ≃ 0
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
x✝ : (n——m).sgn ≃ 0
this✝¹ : ord_sgn (compare n m) ≃ 0
this✝ : ord_sgn (compare n m) ≃ ord_sgn Ordering.eq
this : compare n m = Ordering.eq
⊢ n——m ≃ 0