∀ (x : Int.Linear.Var) (k : ℤ) (p : Int.Linear.Poly),
  Int.Linear.var_eq_cert x k p =
    Int.Linear.Poly.rec (fun x => false)
      (fun k₁ x' p' x_1 =>
        Int.Linear.Poly.rec (fun k₂ => k₁ != 0 && x == x' && k == -k₂ / k₁) (fun x x_2 x_3 x_4 => false) p')
      p