∀ (l₁ : Lean.Level) (k₁ : ℕ) (l₂ : Lean.Level) (k₂ : ℕ),
  (invImage
        (fun x =>
          PSigma.casesOn x fun a a_1 => PSigma.casesOn a_1 fun a_2 a_3 => PSigma.casesOn a_3 fun a_4 a_5 => (a, a_4))
        Prod.instWellFoundedRelation).1
    ⟨l₁, ⟨k₁ + 1, ⟨l₂, k₂⟩⟩⟩ ⟨l₁.succ, ⟨k₁, ⟨l₂, k₂⟩⟩⟩