The Institutionalist Implications of an Odious Debt Doctrine

Sovereigns incur debts, and creditors look to the law to hold sovereigns to their obligations. In legal terms, the question is whether to recognize and define an odious debt defense through a treaty or national legislative acts, on the one hand, or through the decisions of authoritative dispute-settlement bodies, whether international arbitral organs or domestic courts. Moreover, others may think that odious debt doctrine as a means can optimize the social welfare generated by sovereign-debt contracts. Here, Stephan examines the social welfare in the economic sense but attacks the problem from a different direction and concludes that no satisfactory mechanism exists for instituting an odious debt doctrine

KKT reformulation and necessary conditions for optimality in nonsmooth bilevel optimization

For a long time, the bilevel programming problem has essentially been considered as a special case of mathematical programs with equilibrium constraints (MPECs), in particular when the so-called KKT reformulation is in question. Recently though, this widespread believe was shown to be false in general. In this paper, other aspects of the difference between both problems are revealed as we consider the KKT approach for the nonsmooth bilevel program. It turns out that the new inclusion (constraint) which appears as a consequence of the partial subdifferential of the lower-level Lagrangian (PSLLL) places the KKT reformulation of the nonsmooth bilevel program in a new class of mathematical program with both set-valued and complementarity constraints. While highlighting some new features of this problem, we attempt here to establish close links with the standard optimistic bilevel program. Moreover, we discuss possible natural extensions for C-, M-, and S-stationarity concepts. Most of the results rely on a coderivative estimate for the PSLLL that we also provide in this paper

Of Donor Coordination, Free-Riding, Darlings, and Orphans: The dependence of bilateral aid commitments on other bilateral giving

Using data from 1988 to 2007, we examine to what extent bilateral aid flows of an individual donor to a country depend on aid flows from all other bilateral and multilateral donors to that country. We thereby want to assess to what extent donor coordination, free-riding, selectivity, and common donor motivations drive bilateral aid allocation as these determinants would point to different dependence structures. Using approaches from spatial econometrics and controlling for endogeneity using an GMM framework, we find that other bilateral flows lead to a significant (but rather small) increase in aid flows from a particular donor. The effects are particularly pronounced for so-called donor 'orphans' who seem to be collectively shunned by bilateral aid donors. This suggests that donor coordination and free-riding are quantitatively less important than common donor interests and selectivity. --

Fidelity and superconductivity in two-dimensional t-J models

We compute the ground-state fidelity and various correlations to gauge the competition between different orders in two-dimensional t-J-type models. Using exact numerical diagonalization techniques, these quantities are examined for (i) the plain t-J and t-t'-J models, (ii) for the t-J model perturbed by infinite-range d-wave or extended-s-wave superconductivity inducing terms, and (iii) the t-J model, plain and with a d-wave perturbation, in the presence of non-magnetic quenched disorder. Various properties at low hole doping are contrasted with those at low electron filling. In the clean case, our results are consistent with previous work that concluded that the plain t-J model supports d-wave superconductivity. As a consequence of the strong correlations present in the low hole doping regime, we find that the magnitude of the d-wave condensate occupation is small even in the presence of large d-wave superconductivity inducing terms. In the dirty case, we show the robustness of the ground state in the strongly correlated regime against disorder.Comment: 11 pages, 12 figures, as publishe