Two-stage optimal control problems and optimality conditions

When an optimal investment decision is studied for a firm whose capital goods are subject to a delivery lag, a control problem with a time-delay argument in the objective function emerges. Such a problem under a set of simple assumptions is shown to be reducible to a two-stage optimal control problem. The significance of this is that familiar tools from standard optimal control theory are applicable to the resulting two-stage problem. Necessary conditions are presented for a general two-stage problem with an adjustable switching time. Some specific results are also obtained for several special cases.     

The effects of partial-coverage rent control on the price and quantity of rental housing

Rent control is widely used, but its effects are little understood. A two-sector model is provided that predicts the effects of rent control on both the price and quantity of rental housing and allows estimates of the size of these effects with limited amounts of data from jurisdictions which have controlled and uncontrolled sectors. Among other things, the model indicates the relationship between the price of rental housing in the absence of rent control and controlled and uncontrolled rent levels under a partial-coverage regime.     

On the local stability of the solution to optimal control problems

New conditions for the local stability of optimal control problems are presented. The conditions are an extension of the results of a previous study focusing on the solution to problems solvable using calculus of variations. A comparison is made between the conditions introduced here and those presented in the literature. It is shown that our condition is roughly as powerful as the one presented by Sorger (J. Math. Anal. Appl. 148 (1990) 191) but it is easier to check.     

On the equivalence of the Arrow impossibility theorem and the Brouwer fixed point theorem when individual preferences are weak orders

We will show that in the case where there are two individuals and three alternatives (or under the assumption of the free-triple property), and individual preferences are weak orders (which may include indifference relations), the Arrow impossibility theorem [Arrow, K.J., 1963. Social Choice and Individual Values, second ed. Yale University Press] that there exists no binary social choice rule which satisfies the conditions of transitivity, Pareto principle, independence of irrelevant alternatives, and non-existence of dictator is equivalent to the Brouwer fixed point theorem on a 2-dimensional ball (circle). Our study is an application of ideas by Chichilnisky [Chichilnisky, G., 1979. On fixed points and social choice paradoxes. Economics Letters 3, 347–351] to a discrete social choice problem, and also it is in line with the work by Baryshnikov [Baryshnikov, Y., 1993. Unifying impossibility theorems: a topological approach. Advances in Applied Mathematics 14, 404–415].     

An algorithm for the solution of stochastic optimal control problems for large nonlinear econometric models

This paper considers the problem of solving an optimal control problem for large dynamic economic models which are both nonlinear and stochastic. It proposes a technique which combines conventional deterministic optimal control algorithms with the procedure of stochastic simulation, which calculates a numerical approximation to the distribution of the models endogenous variables. The new technique is computationally feasible for even large nonlinear models and, as an illustration of this, the Bank of England's large quarterly forecasting model is used in an example.     

Discussion of dynamic programming and linear programming approaches to stochastic control and optimal stopping in continuous time

This paper seeks to highlight two approaches to the solution of stochastic control and optimal stopping problems in continuous time. Each approach transforms the stochastic problem into a deterministic problem. Dynamic programming is a well-established technique that obtains a partial/ordinary differential equation, variational or quasi-variational inequality depending on the type of problem; the solution provides the value of the problem as a function of the initial position (the value function). The other method recasts the problems as linear programs over a space of feasible measures. Both approaches use Dynkin’s formula in essential but different ways. The aim of this paper is to present the main ideas underlying these approaches with only passing attention paid to the important and necessary technical details.     

北京市房价过高的原因和房价控制

北京市房价过高 ,这是公认的事实 ,而且房价与当地居民的收入又严重背离。找出房价过高的原因 ,进而找到降低房价的办法是一个亟待研究的课题。本文通过分析房价的构成因素 ,发现土地费用过高是造成北京市房价过高的主要原因。加大政府对土地的管理 ,严禁炒卖地皮 ,盘活市内存量土地 ,严格控制城市建成区“摊大饼”式地向郊区扩展 ,才能达到合理利用土地并降低房价的目的。　　一、北京市房价过高的原因　　国家统计局月度形势报告显示 ,2 0 0 1年 6月份全国大中城市商品房每平方米平均销售价格为2 30 4元。北京列榜首 ,每平方米平均售价达 …     

Central limit theorem for linear eigenvalue statistics of the Wigner and the sample covariance random matrices

We consider n × n real symmetric random matrices n ^?1/2 W with independent (modulo symmetry condition) entries and the (null) sample covariance matrices n ^?1 A ^T A with independent entries of m × n matrix A. Assuming first that the 4th cumulant (excess) κ ₄ of entries of W and A is zero and that their 4th moments satisfy a Lindeberg type condition, we prove that linear statistics of eigenvalues of the above matrices satisfy the central limit theorem (CLT) as n → ∞, m → ∞, ${m/n\rightarrow c\in[0,\infty)}$ with the same variance as for Gaussian matrices if the test functions of statistics are smooth enough (essentially of the class ${\mathbb{C}^5}$ ). This is done by using a simple “interpolation trick”. Then, by using a more elaborated techniques, we prove the CLT in the case of non-zero excess of entries for essentially ${\mathbb{C}^4}$ test function. Here the variance contains additional term proportional to κ ₄. The proofs of all limit theorems follow essentially the same scheme.     

国外土地利用管制与住宅价格研究综述

对国外土地利用管制与住宅价格相互关系的研究进行归纳.研究表明,土地利用管制与住宅价格之间存在很大的不确定性,且不同的控制措施对住房价格的影响具有累加效应.因此,实践中应明确管制的目的,谨防垄断性区划的存在.     

Asymptotically optimal nonparametric one- and two-way analysis of variance tests for the log linear model under censoring

We considerr ×c populations with failure ratesλ _ij(t) satisfying the condition

企业预算与管理控制(一)

企业预算以量化标准的形式,将企业战略计划和年度经营计划具体化,从而使企业战略的实施与控制具备了可操作的基础。企业预算的编制与执行使企业管理控制系统的核心,涉及企业行为、文化与技术方法选择等各个方面。为此我们特分两期讨论有关内容。本期主要介绍企业计划与预算的关系以及影响预算编制的重要行为因素;下一期将阐述不同预算方法的适用性及其管理控制的功能。     

企业预算与管理控制(二)

企业预算以量化标准的形式,将企业战略计划和年度经营计划具体化,从而使企业战略的实施与控制具备了可操作的基础。企业预算的编制与执行使企业管理控制系统的核心,涉及企业行为、文化与技术方法选择等各个方面。上期我们主要介绍了企业计划与预算的关系以及影响预算编制的重要行为因素;本期将阐述不同预算方法的适用性及其管理控制的功能。     

房价逆调控而上涨的政策性原因与对策

针对近期我国房价快速上涨、房地产商及高价商品房主导市场、住房投机愈演愈烈、中低收入阶层住房困难等问题,作者对北京房地产市场进行了调查研究,并从中发现了一些值得探讨的问题.本文通过对廉租房、经济适用房、商品房、出租房现状及相关政策进行客观分析,揭示了我国高房价的症结及一些政策方面的原因.文中以调查研究为依据,提出了强化政府责任、完善住房保障政策的个人看法与建议.     

GMM with many weak moment conditions: Replication and application of Newey and Windmeijer (2009)

In a recent article Newey and Windmeijer (Generalized method of moments with many weak moment conditions. Econometrica 2009; 77 (3): 687–719) propose a new variance estimator for generalized empirical likelihood. In Monte Carlo examples they show that t‐statistics based on the new variance estimator have nearly correct size. I have replicated their Monte Carlo simulations and in addition used the new variance estimator to re‐estimate Angrist and Krueger's (Does compulsory school attendance affect schooling and earnings? Quarterly Journal of Economics 1991; 106 (4): 979–1014) returns to education. Copyright © 2011 John Wiley & Sons, Ltd.     

Estimation problems for rectangular distributions (or the taxi problem revisited)

The problem of estimating the unknown upper bound on the basis of a sample of sizen from a uniform or rectangular distribution on [0, ] has considerable interest. This or the analogous discrete version is variously known as the Taxi-problem or the German bomb (or Tank) problem and has a long history. The emphasis here is on estimation of through the lengths of the observed gaps or spacings which seem natural for this problem.     

浅谈广州南沙港区(南段)真空软基处理监理控制

针对工程内容及合同要求，采取有效的监控措施。