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.     

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.     

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。     

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。     

Differentiating weak ties and strong ties among external sources of influences for enterprise resource planning (ERP) adoption

Enterprise resource planning (ERP) systems represent a major IT adoption decision. ERP adoption decisions, in the chemicals and allied products sectors, were examined between 1994 and 2005. Networks of strong ties and weak ties partners are investigated. Results show that neighbouring companies linked with strong ties can have an influence on organisations making such adoption decision. Past decisions made by major trading partners have a significant influence on the decision to adopt an ERP system for a given organisation. This reflects the complex nature of the knowledge required for such adoption.     

On the existence of an increasing symmetric equilibrium in (k + 1)-st price common value auctions

In a classical result, Milgrom (1981a) established that the Monotone Likelihood Ratio Property (MLRP) is a sufficient condition for the existence of an increasing symmetric equilibrium in (k + 1)-st price common value auctions. We show: (1) If MLRP is violated, then for any number of bidders and objects there exists a distribution of the common value such that no increasing symmetric equilibrium exists; (2) If MLRP is violated, then for any distribution of the common value there exist infinitely many pairs of the number of bidders and the number of objects such that an increasing symmetric equilibrium does not exist; (3) There are examples where an increasing symmetric equilibrium exists even when the signal distribution violates MLRP.     

论GDP、CPI与国民经济总价值TH及通货膨胀、紧缩率i

本文通过使用"全面价值论"的观点,找到了国民经济总价值、剩余价值的实时计算指标及度量方法,也就是具体找到了GDP的完善化指标。给出了全面价值的价值规律指导下的国民经济全面协调发展的指路明灯。此外,通过全面价值论观点,还找到了符合通货膨胀或通货紧缩定义的"全部商品"的通货膨胀率或通货紧缩率计算公式,通过全部商品的通货膨胀率或通货紧缩率的具体计算,可以还原纸币本身的时间价值,使纸币起到实物货币的功能,成为根本治理通货膨胀、通货紧缩及金融危机的基本实操。     

A control function approach for testing the usefulness of trending variables in forecast models and linear regression

Many predictors employed in forecasting macroeconomic and finance variables display a great deal of persistence. Tests for determining the usefulness of these predictors are typically oversized, overstating their importance. Similarly, hypothesis tests on cointegrating vectors will typically be oversized if there is not an exact unit root. This paper uses a control variable approach where adding stationary covariates with certain properties to the model can result in asymptotic normal inference for prediction regressions and cointegration vector estimates in the presence of possibly non-unit root trending covariates. The properties required for this result are derived and discussed.     

Current practice in the modelling of age,period and cohort effects with panel data: a commentary on Tawfik et al. (2012), Clarke et al. (2009), and McCulloch (2012)

This comment assesses how age, period and cohort (APC) effects are modelled with panel data in the social sciences. It considers variations on a 2-level multilevel model which has been used to show apparent evidence for simultaneous APC effects. We show that such an interpretation is often misleading, and that the formulation and interpretation of these models requires a better understanding of APC effects and the exact collinearity present between them. This interpretation must draw on theory to justify the claims that are made. By comparing two papers which over-interpret such a model, and another that in our view interprets it appropriately, we outline best practice for researchers aiming to use panel datasets to find APC effects, with an understanding that it is impossible for any statistical model to find and separate all three effects.