case a.succ.succ n m ihn ihm =>
  sorry
a b : String
nab : ¬a = b
n m : ℕ
ihn :
  Ø ⋁ Sinf_term.subst (fromNat n) b (fromNat m) +ₛ fromNat m =ₛ fromNat m +ₛ Sinf_term.subst (fromNat n) b (fromNat m) →
    Ø ⋁
      Sinf_term.subst (fromNat n) b (fromNat m)↗ +ₛ fromNat m =ₛ fromNat m +ₛ Sinf_term.subst (fromNat n) b (fromNat m)↗
ihm :
  Ø ⋁
    Sinf_term.subst (fromNat n) b (fromNat m↗) +ₛ fromNat m↗ =ₛ fromNat m↗ +ₛ Sinf_term.subst (fromNat n) b (fromNat m↗)
⊢ Ø ⋁
    Sinf_term.subst (fromNat n) b (fromNat m↗)↗ +ₛ fromNat m↗ =ₛ
      fromNat m↗ +ₛ Sinf_term.subst (fromNat n) b (fromNat m↗)↗
no goals