∀ {α β : AlexDisc} (e : ↑α.toTopCat ≃ₜ ↑β.toTopCat),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.ConcreteCategory.ofHom ↑e)
      (CategoryTheory.ConcreteCategory.ofHom ↑e.symm) =
    CategoryTheory.CategoryStruct.id α