Discounting long run average growth in stochastic dynamic programs

Summary. Finding solutions to the Bellman equation often relies on restrictive boundedness assumptions. In this paper we develop a method of proof that allows to dispense with the assumption that returns are bounded from above. In applications our assumptions only imply that long run average (expected) growth is sufficiently discounted, in sharp contrast with classical assumptions either absolutely bounding growth or bounding each period (instead of long run) maximum (instead of average) growth. We discuss our work in relation to the literature and provide several examples. Received: July 26, 2000; revised version: July 10, 2002 RID="*" ID="*" I am specially grateful to Cuong Le Van and to anonymous referee for detecting an error in a previous version of this paper and for suggestions that sensibly improved the paper. Comments and suggestions are also acknowledged to Michele Boldrin, Raouf Boucekkine, Fabrice Collard, Tim Kehoe, Omar Licandro, and Luis Puch. I am also indebted to participants to the III Summer School on Economic Theory held at the Universidade de Vigo, the Macroeconomics Workshop at the Universitat Autò}noma de Barcelona, and the Econometrics Seminar at Tilburg University. Financial support from the Belgian government, under project PAI P4/01, at the IRES-UCL, from a European Marie Curie fellowship, Grant HPMF-CT-1999-00410, at the CEPREMAP, and from IVIE and Spanish Ministerio de Ciencia y Tecnología and FEDER, under project BEC2001-0535, at the Universidad de Alicante, is gratefully acknowledged.     

基于多目标决策模型的区域旅游可持续发展研究——以西藏自治区为例

旅游的可持续发展决定于旅游与人口、社会、资源、环境之间的协调发展,本文建立了西藏地区旅游可持续发展系统的多目标规划模型,针对西藏旅游业发展的三大目标：经济目标、生态目标与群众目标,采用模式搜索算法对多目标规划模型进行求解,获得西藏旅游可持续发展系统不同发展战略下的求解结果。依据求解结果,提出了对西藏旅游可持续发展系统进行过程控制的相关对策建议。     

基于投资消费模型的购房者行为分析

在生命周期投资消费模型中首次考虑了投资者二套房投资。利用动态规划原理,在特殊的两期情况下进一步假设投资者的投资需求具有层次性,给出投资者首次购房决策的一种简便方法。另外,还对近年来住宅市场快速增长的内在动力进行了探讨。     

Failure Discrimination and Rating of Enterprises by Semi-Definite Programming

We propose a new method forfailure discrimination and rating of enterprises using financialdata compiled from their balance sheets. No particular distributional assumption is made on the underlying data. Our method automatically discriminates and rates many enterprises using mathematical programming methods. We separate multi-dimensional data byhyperplane and hyper-ellipsoid, so that we can interpretthe results of classification from the geometric point of view. Theproblem to be solved here is a linear programming problem orsemi-definite programming problem which can be solved efficiently byinterior point algorithms. Numerical simulations usingreal data show that hyper-ellipsoid separation generates a result which can be used for practical purposes.     

车辆修理集中化布局的双层规划模型研究

在对车辆修理点布局问题分析的基础上,以规划期内修理点的改扩建费用、运营费用和运输费用之和最小为目标建立上层模型,以运输费用最小为目标建立下层模型,以此建立了车辆修理点布局的双层规划优化模型,并给出了相应的求解算法。模型具有较好的适用性和实用性,为铁路车辆修理点的进一步优化调整奠定了较好的理论基础。     

Hub location problems in transportation networks

In this paper we propose a 4-index formulation for the uncapacitated multiple allocation hub location problem tailored for urban transport and liner shipping network design. This formulation is very tight and most of the tractable instances for MIP solvers are optimally solvable at the root node. While the existing state-of-the-art MIP solvers fail to solve even small size instances of problem, our accelerated and efficient primal (Benders) decomposition solves larger ones. In addition, a very efficient greedy heuristic, proven to be capable of obtaining high quality solutions, is proposed. We also introduce fixed cost values for Australian Post (AP) dataset.