Bridge 3 derives the COCM invariant from the bulk geometry of under explicit working hypotheses. This note identifies four open problems that must be resolved before the derivation can be regarded as fully closed: the consistency of the background ansatz with the bulk field equations, the perturbative compatibility of the Israel junction conditions on both branes, the global existence and stability of the bulk–brane solution, and the uniqueness of the orbital interpretation of the formal structure. Each problem is stated precisely. No claim is made here regarding their resolution.
José Luis Vázquez González (Tue,) studied this question.