Trading reliability targets within a supply chain using Shapley's value

The development of complex systems involves a multi-tier supply chain, with each organisation allocated a reliability target for their sub-system or component part apportioned from system requirements. Agreements about targets are made early in the system lifecycle when considerable uncertainty exists about the design detail and potential failure modes. Hence resources required to achieve reliability are unpredictable. Some types of contracts provide incentives for organisations to negotiate targets so that system reliability requirements are met, but at minimum cost to the supply chain. This paper proposes a mechanism for deriving a fair price for trading reliability targets between suppliers using information gained about potential failure modes through development and the costs of activities required to generate such information. The approach is based upon Shapley's value and is illustrated through examples for a particular reliability growth model, and associated empirical cost model, developed for problems motivated by the aerospace industry. The paper aims to demonstrate the feasibility of the method and discuss how it could be extended to other reliability allocation models

Stochastic Optimal Control, International Finance and Debt

We use stochastic optimal control-dynamic programming (DP) to derive the optimal foreign debt/net worth, consumption/net worth, current account/net worth, and endogenous growth rate in an open economy. Unlike the literature that uses an Intertemporal Budget Constraint (IBC) or the Maximum Principle, the DP approach does not require perfect foresight or certainty equivalence. Errors of measurement and the effects of unanticipated shocks are corrected in an optimal manner. We contrast the DP and IBC approaches, show how the results of the dynamic programming approach can be interpreted in a traditional simple mean-variance/Tobin-Markowitz context, and explain why our results are generalizations of the Merton model.stochastic optimal control, foreign debt, international finance, vulnerability to external shocks, sustainable current account deficits

Domination and Decomposition in Multiobjective Programming

During the last few decades, multiobjective programming has received much attention for both its numerous theoretical advances as well as its continued success in modeling and solving real-life decision problems in business and engineering. In extension of the traditionally adopted concept of Pareto optimality, this research investigates the more general notion of domination and establishes various theoretical results that lead to new optimization methods and support decision making. After a preparatory discussion of some preliminaries and a review of the relevant literature, several new findings are presented that characterize the nondominated set of a general vector optimization problem for which the underlying domination structure is defined in terms of different cones. Using concepts from linear algebra and convex analysis, a well known result relating nondominated points for polyhedral cones with Pareto solutions is generalized to nonpolyhedral cones that are induced by positively homogeneous functions, and to translated polyhedral cones that are used to describe a notion of approximate nondominance. Pareto-oriented scalarization methods are modified and several new solution approaches are proposed for these two classes of cones. In addition, necessary and sufficient conditions for nondominance with respect to a variable domination cone are developed, and some more specific results for the case of Bishop-Phelps cones are derived. Based on the above findings, a decomposition framework is proposed for the solution of multi-scenario and large-scale multiobjective programs and analyzed in terms of the efficiency relationships between the original and the decomposed subproblems. Using the concept of approximate nondominance, an interactive decision making procedure is formulated to coordinate tradeoffs between these subproblems and applied to selected problems from portfolio optimization and engineering design. Some introductory remarks and concluding comments together with ideas and research directions for possible future work complete this dissertation

Sovereign Net Worth: An Analytical Framework

The Fiscal Responsibility Act requires the Crown to articulate targets for a series of fiscal variables, including net worth. Given the dramatic improvement in the fiscal position in recent years, a critical policy question relates to how (and which) measures of Crown net worth should be targeted. This paper sets out a framework for targeting Crown net worth. It does so by supplementing the GAAP-based measure with forward-looking information about spending and tax revenue. The paper argues that targeting net worth for the Crown requires the estimation of a path, rather than a static level.

Equitable Efficiency in Multiple Criteria Optimization

Equitable efficiency in multiple criteria optimization was introduced mathematically in the middle of nineteen-nineties. The concept tends to strengthen the notion of Pareto efficiency by imposing additional conditions on the preference structure defining the Pareto preference. It is especially designed to solve multiple criteria problems having commensurate criteria where different criteria values can be compared directly. In this dissertation we study some theoretical and practical aspects of equitably efficient solutions. The literature on equitable efficiency is not very extensive and provides very limited number of ways of generating such solutions. After introducing some relevant notations, we develop some scalarization based methods of generating equitably efficient solutions. The scalarizations developed do not assume any special structure of the problem. We prove an existence result for linear multiple criteria problems. Next, we show how equitably efficient solutions arise in the context of a particular type of linear complementarity problem and matrix games. The set of equitably efficient solutions, in general, is a subset of efficient solutions. The multiple criteria alternative of the linear complementarity problem dealt in our dissertation has identical efficient and equitably efficient solution sets. Finally, we demonstrate the relevance of equitable efficiency by applying it to the problem of regression analysis and asset allocation

Stability of utility-maximization in incomplete markets

The effectiveness of utility-maximization techniques for portfolio management relies on our ability to estimate correctly the parameters of the dynamics of the underlying financial assets. In the setting of complete or incomplete financial markets, we investigate whether small perturbations of the market coefficient processes lead to small changes in the agent's optimal behavior derived from the solution of the related utility-maximization problems. Specifically, we identify the topologies on the parameter process space and the solution space under which utility-maximization is a continuous operation, and we provide a counterexample showing that our results are best possible, in a certain sense. A novel result about the structure of the solution of the utility-maximization problem where prices are modeled by continuous semimartingales is established as an offshoot of the proof of our central theorem.Comment: to appear in Stochastic Processes and Application

CROP DIVERSITY AS THE DERIVED OUTCOME OF FARMERS' 'SURVIVAL FIRST' MOTIVES IN ETHIOPIA: WHAT ROLE FOR ON-FARM CONSERVATION OF SORGHUM GENETIC RESOURCES?

Crop genetic resources are the building blocks of sustainable agricultural development due to their relevance not only as inputs for variety development but also as indigenous crop insurance mechanisms through traditional variety portfolio management. Their continuous survival is, however, threatened by natural and human driven factors. This threat has induced the need for designing conservation measures. Among the in situ and ex situ conservation options available to conserve crop genetic resources, on-farm conservation has recently attracted enormous attention. To make this option operational, placing incentives (that link conservation with utilization) and removal of perverse incentives are believed to be crucial so that landraces of no immediate interest to farmers can be conserved. However, before designing sound incentives and/or removing perverse incentives, we have to understand farmers' motives for managing a portfolio of traditional varieties. To address our objective, we have adopted a utility based model that considers on-farm diversity as a positive externality of farmers' livelihood decisions. Accordingly, on-farm diversity is considered as the derived outcome of farmers' revealed preferences subject to their concerns and constraints. To empirically test the relationships, a Poisson regression model is estimated using rural household survey data collected from 198 sorghum growing farmers in East Ethiopia. The results have shown the most important diversity promoting factors and those factors detaching the link between farmers' 'survival first' motives and their spillover effects on sorghum diversity. Based on the results, the paper concludes outlining the policy implications of the findings.On-farm conservation, sorghum genetic resources, incentives, Poisson regression, Ethiopia, Crop Production/Industries,

The Impact of Financial Reform on Private Savings in Bangladesh

Over the course of the last decade, Bangladesh has implemented a broad-based program of financial and market reforms, encompassing changes in the structure of the financial system, prudential and supervisory frameworks, and monetary management. This paper estimates a savings function to evaluate the impact of various determinants of private savings in Bangladesh—with special emphasis on the impact of financial reform. The results show that the level of income, real interest rates, and the share of agriculture in GDP have a positive impact on the savings rate. Dependency rate and public savings rate, on the other hand, have a negative impact on private savings. Interestingly, the financial reform index has a negative impact on private savings. Hence reforms that were initiated since the late 1980s had actually reduced savings