The challenge of reducing international trade and migration barriers

While barriers to trade in most goods and some services including capital flows have been reduced considerably over the past two decades, many remain. Such policies harm most the economies imposing them, but the worst of the merchandise barriers (in agriculture and textiles) are particularly harmful to the world's poorest people, as are barriers to worker migration across borders. This paper focuses on how costly those anti-poor trade policies are, and examines possible strategies to reduce remaining distortions. Two opportunities in particular are addressed: completing the Doha Development Agenda process at the World Trade Organization (WTO), and freeing up the international movement of workers. A review of the economic benefits and adjustment costs associated with these opportunities provides the foundation to undertake benefit/cost analysis required to rank this set of opportunities against those aimed at addressing the world's other key challenges as part of the Copenhagen Consensus project. The paper concludes with key caveats and suggests that taking up these opportunities could generate huge social benefit/cost ratios that are considerably higher than the direct economic ones quantified in this study, even without factoring in their contribution to alleviating several of the other challenges identified by that project, including malnutrition, disease, poor education and air pollution.Economic Theory&Research,Environmental Economics&Policies,Emerging Markets,Free Trade,Trade Policy

Dependent choice, properness, and generic absoluteness

We show that Dependent Choice is a sufficient choice principle for developing the basic theory of proper forcing, and for deriving generic absoluteness for the Chang model in the presence of large cardinals, even with respect to -preserving symmetric submodels of forcing extensions. Hence, not only provides the right framework for developing classical analysis, but is also the right base theory over which to safeguard truth in analysis from the independence phenomenon in the presence of large cardinals. We also investigate some basic consequences of the Proper Forcing Axiom in, and formulate a natural question about the generic absoluteness of the Proper Forcing Axiom in and. Our results confirm as a natural foundation for a significant portion of classical mathematics and provide support to the idea of this theory being also a natural foundation for a large part of set theory

On the Properties of the Compound Nodal Admittance Matrix of Polyphase Power Systems

Most techniques for power system analysis model the grid by exact electrical circuits. For instance, in power flow study, state estimation, and voltage stability assessment, the use of admittance parameters (i.e., the nodal admittance matrix) and hybrid parameters is common. Moreover, network reduction techniques (e.g., Kron reduction) are often applied to decrease the size of large grid models (i.e., with hundreds or thousands of state variables), thereby alleviating the computational burden. However, researchers normally disregard the fact that the applicability of these methods is not generally guaranteed. In reality, the nodal admittance must satisfy certain properties in order for hybrid parameters to exist and Kron reduction to be feasible. Recently, this problem was solved for the particular cases of monophase and balanced triphase grids. This paper investigates the general case of unbalanced polyphase grids. Firstly, conditions determining the rank of the so-called compound nodal admittance matrix and its diagonal subblocks are deduced from the characteristics of the electrical components and the network graph. Secondly, the implications of these findings concerning the feasibility of Kron reduction and the existence of hybrid parameters are discussed. In this regard, this paper provides a rigorous theoretical foundation for various applications in power system analysi