exact AA.substFn (Rel.symm ‹-a - -b ≃ b - a›) ‹Positive (b - a)›
ℕ : Type
inst✝⁷ : Natural ℕ
ℤ : Type
inst✝⁶ : Core ℤ
inst✝⁵ : Addition ℤ
inst✝⁴ : Multiplication ℤ
inst✝³ : Negation ℤ
inst✝² : Subtraction ℤ
inst✝¹ : Sign ℤ
inst✝ : Order ℤ
a b : ℤ
this✝ : -a - -b ≃ b - a
x✝ : a < b
this : Positive (b - a)
⊢ Positive (-a - -b)
no goals