Directed Search for Equilibrium Wage–Tenure Contracts

I construct a theoretical framework in which firms offer wage–tenure contracts to direct the search by risk‐averse workers. All workers can search, on or off the job. I characterize an equilibrium and prove its existence. The equilibrium generates a nondegenerate, continuous distribution of employed workers over the values of contracts, despite that all matches are identical and workers observe all offers. A striking property is that the equilibrium is block recursive; that is, individuals' optimal decisions and optimal contracts are independent of the distribution of workers. This property makes the equilibrium analysis tractable. Consistent with stylized facts, the equilibrium predicts that (i) wages increase with tenure, (ii) job‐to‐job transitions decrease with tenure and wages, and (iii) wage mobility is limited in the sense that the lower the worker's wage, the lower the future wage a worker will move to in the next job transition. Moreover, block recursivity implies that changes in the unemployment benefit and the minimum wage have no effect on an employed worker's job‐to‐job transitions and contracts.     

Information Percolation With Equilibrium Search Dynamics

We solve for the equilibrium dynamics of information sharing in a large population. Each agent is endowed with signals regarding the likely outcome of a random variable of common concern. Individuals choose the effort with which they search for others from whom they can gather additional information. When two agents meet, they share their information. The information gathered is further shared at subsequent meetings, and so on. Equilibria exist in which agents search maximally until they acquire sufficient information precision and then search minimally. A tax whose proceeds are used to subsidize the costs of search improves information sharing and can, in some cases, increase welfare. On the other hand, endowing agents with public signals reduces information sharing and can, in some cases, decrease welfare.     

Money in Search Equilibrium,in Competitive Equilibrium,and in Competitive Search Equilibrium

We compare three market structures for monetary economies: bargaining (search equilibrium); price taking (competitive equilibrium); and price posting (competitive search equilibrium). We also extend work on the microfoundations of money by allowing a general matching technology and entry. We study how equilibrium and the effects of policy depend on market structure. Under bargaining, trade and entry are both inefficient, and inflation implies first‐order welfare losses. Under price taking, the Friedman rule solves the first inefficiency but not the second, and inflation may actually improve welfare. Under posting, the Friedman rule yields the first best, and inflation implies second‐order welfare losses.     

创新中的组织搜索:概念的重新架构

系统地回顾了2000年以来创新领域关于组织搜索的文献。主要解决2个问题:①组织搜索产生混乱的原因是什么?②怎样才能澄清这些混乱,减少研究中的模糊性?为了回答这2个问题,利用搜索广度和搜索深度2个不同的搜索方向对组织搜索建立了分类模型,发现产生混乱的根本原因在于对搜索广度范围的界定,以及与搜索深度的平衡路径存在不一致。针对以上2个问题,首先从知识类型和知识距离2个维度,提出了多维跨界搜索的概念;然后提出了一个演化式搜索的整合框架,为搜索广度和搜索深度的平衡提供具体的实现路径。旨在协调和整合现有研究中存在的不一致,并为将来的研究提供建议,同时对企业的实践活动提供指导。     

Standard directed search strategies and their applications

Given a digraph that contains an intruder hiding on vertices or along edges, a directed searching problem is to find the minimum number of searchers required to capture the intruder. In this paper, we propose the standard directed search strategies, which can simplify arguments in proving search numbers, lower bounds, and relationships between search models. Using these strategies, we characterize k-directed-searchable graphs when k≤3. We also use standard directed search strategies to investigate the searching problems on oriented grids. We give tight lower and upper bounds for the directed search number of general oriented grids. Finally, we show how to compute the directed search number of a Manhattan grid. Yang’s research was supported in part by NSERC and MITACS.     

The Newsvendor Model with Consumer Search Costs

We study the newsvendor problem when consumers are heterogeneous either in their valuations of the newsvendor's product, in their valuations of an outside option available to them, or in both valuations. In this context, we observe that the outside option, which represents the value that a given consumer associates with choosing not to purchase the newsvendor's product, may be interpreted as a search cost. Taking into consideration whether consumers' valuations differ on either one dimension of heterogeneity or on both dimensions, we develop a framework for classifying newsvendor models that incorporate demand‐management effects. In particular, we show that this framework includes both the newsvendor model with price‐dependent demand and the newsvendor model with endogenous demand as special cases. In addition to making a conceptual contribution by developing and drawing insights from this framework, we make technical contributions by providing more general sufficient conditions under which the underlying optimization problems are well behaved.     

网络搜索与经济行为相关性研究综述

网络搜索与经济行为的相关性研究是当前国外学者的研究热点。按照研究问题的层次划分,现有研究可以分为宏观、中观及微观三个领域。本文系统整理了现有研究内容,总结了主要研究方法,指出了现有研究中存在的重点和难点问题,并探讨了未来可能的研究方向。     

Resolution Search and Dynamic Branch-and-Bound

A novel approach to pure 0-1 integer programming problems called Resolution Search has been proposed by Chvatal (Discrete Applied Mathematics, vol. 73, pp. 81–99, 1997) as an alternative to implicit enumeration, with a demonstration that the method can yield more effective branching strategies. We show that an earlier method called Dynamic Branch-and-Bound (B&B) yields the same branching strategies as Resolution Search, and other strategic alternatives in addition. Moreover, Dynamic B&B is not restricted to pure 0-1 problems, but applies to general mixed integer programs containing both general integer and continuous variables.We provide examples comparing Resolution Search to enhanced variants. We also show the relation of these approaches to Dynamic B&B, suggesting the value of further study of this neglected approach.     

搜索引擎关键字广告的竞争分析

搜索引擎关键字广告是一种新兴的获得巨大成功的在线营销方式.本文分析了搜索引擎广告位的拍卖规则,给出了在质量因子因素下,广告主的竞价行为.首先给出了广告主单阶段同时行动的竞价均衡,在该情况下,广告主单独竞价选择对自己最有利的策略;其次给出了多阶段情况下,给定一个广告主的最小加价策略,另外一个广告主的最优策略,并给出了相关的证明;最后用实际观测到的数据对该策略进行验证.另外还给出了三个相关的推论,该推论对于搜索引擎如何提高自己的收益有一定的指导意义.     

基于图的广度搜索的进度生成机制

启发式算法是解决资源受限的项目调度问题的经典方法之一,通常用来生成元启发算法初始解,传统的串行（SSGS）和并行（PSGS）是生成项目调度方案的经典机制,本文基于图的广度优先搜索算法,提出了一种考虑任务节点位置因素的广度生成机制（BSSGS）,并验证了算法的效果。借鉴广度搜索算法定义进度生成机制中的当前任务集合C、候选任务集合D以及阶段变量g等,对各任务节点进行层次划分并定义任务调度秩序;结合优先规则选择候选任务j^*并进行资源R_k（t）调度更新,进而生成完整的调度方案;案例分析表明新机制在满足优先规则和资源约束的同时兼顾了任务节点在网络中位置因素,拥有对于局部复杂网络不回避,对关键节点及时调度等明显优势;选择PSPLIB中算例,在不同优先规则下对新机制进行了测试,测试结果表明新的进度生成机制在LPT、SPT、MTS和MIS等优先规则下,在平均最短工期、平均资源利用率及最优调度方案率等方面优于串行和并行进度生成机制,且算法时间复杂度与传统机制相比并未增加,仍为O（J²,K）。     

Assortative Matching with Explicit Search Costs

In this paper, I analyze a decentralized search and matching economy with transferable utility composed of heterogeneous agents. I explore whether Becker's assortative matching result generalizes to an economy where agents engage in costly search. In an economy with explicit additive search costs, complementarities in joint production (supermodularity of the joint production function) lead to assortative matching. This is in contrast to previous literature, which had shown that in a search economy with discounting, assortative matching may fail even when the joint production function is supermodular.     

Liquidity in Asset Markets With Search Frictions

We develop a search‐theoretic model of financial intermediation in an over‐the‐counter market and study how trading frictions affect the distribution of asset holdings and standard measures of liquidity. A distinctive feature of our theory is that it allows for unrestricted asset holdings, so market participants can accommodate trading frictions by adjusting their asset positions. We show that these individual responses of asset demands constitute a fundamental feature of illiquid markets: they are a key determinant of trade volume, bid–ask spreads, and trading delays—the dimensions of market liquidity that search‐based theories seek to explain.     

GRASP with a New Local Search Scheme for Vehicle Routing Problems with Time Windows

The NP-Hard Vehicle Routing Problem with Time Windows (VRPTW) is one of the major transportation problems. In this paper, a Greedy Randomized Adaptive Search Procedure (GRASP) for VRPTW is discussed for minimizing the fleet size and the travel distance. There are two phases within each GRASP iteration: construction phase and local search phase. In the construction phase, the initial solution is computed by applying an adaptive randomized greedy function. In the local search phase, the search procedure is applied to the constructed initial solution obtained by the construction phase for an improvement. In this paper, we propose an improved solution technique by using new local search ideas and new lower bounding procedures. In addition, we report computational results and address some practical issues in this area.     

车辆路径问题的禁忌搜索算法研究

论文在对车辆路径问题进行简单描述的基础上,通过设计一种新的解的表示方法构造了求解该问题的一种新的禁忌搜索算法,并进行了实验计算。计算结果表明,用本文设计的禁忌搜索算法求解车辆路径问题,不仅可以取得很好的计算结果,而且算法的计算效率较高,收敛速度较快,计算结果也较稳定。     

城镇居民预防性储蓄动机的异质性及强度研究

在具有不确定出行时间的交通网络中,假设出行者的参考点是异质的,服从某一连续分布函数,且风险偏好参数是依赖于参考点的,建立了一个基于累积前景理论的多用户网路均衡模型。研究表明,不同类的用户对风险的反应是不一样的,具有高参考点和低参考点的出行者均倾向于选择风险高的路径以期获得较高的感知价值,而具有中等参考点的出行者则倾向于选择风险较低的路径。此外,对两种交通管理措施进行了敏感性分析,结果表明,道路拓宽对于提高整个社会的感知价值是一个有效的方法,但其边际效益是递减的。然而,就风险管理而言,不同类的用户表现出不同的喜好。一般来说,具有低参考点的出行者能够从这一方法中受益,而具有高参考点的出行者则会失去潜在的风险收益。     

有限战略式博弈纯战略均衡求解的新算法

针对现有寻找有限战略式博弈纯战略均衡方法的缺陷,本文证明了一个战略组合是纯战略蚋什均衡的充分必要条件,并根据该条件提出的求解此类博弈模型的纯战略均衡一个算法,最后用一个算例验证了该算法的有效性.     

禁忌搜索算法在单分配多枢纽轴辐式物流网络中的应用

随着经济的发展,轴辐式网络因有提高运输效率,优化资源配置,产生范围经济等作用越来越多的受到各方面学者的关注。本文对轴辐式网络进行优化分析,改进轴辐式网络的多重分配多枢纽中位问题模型,得到无容量限制的单分配多枢纽中位问题模型(USApHLP)的混合整数线性规划模型,并采用改进的禁忌搜索智能算法来求解,通过算例验证了禁忌搜索算法可以有效的求解单分配多枢纽中位问题。     

Necessity Is the Mother of Invention: Input Supplies and Directed Technical Change

This study provides causal evidence that a shock to the relative supply of inputs to production can (1) affect the direction of technological progress and (2) lead to a rebound in the relative price of the input that became relatively more abundant (the strong induced‐bias hypothesis). I exploit the impact of the U.S. Civil War on the British cotton textile industry, which reduced supplies of cotton from the Southern United States, forcing British producers to shift to lower‐quality Indian cotton. Using detailed new data, I show that this shift induced the development of new technologies that augmented Indian cotton. As these new technologies became available, I show that the relative price of Indian/U.S. cotton rebounded to its pre‐war level, despite the increased relative supply of Indian cotton. This is the first paper to establish both of these patterns empirically, lending support to the two key predictions of leading directed technical change theories.     

An Equilibrium Theory of Learning,Search, and Wages

We examine the labor market effects of incomplete information about the workers' own job‐finding process. Search outcomes convey valuable information, and learning from search generates endogenous heterogeneity in workers' beliefs about their job‐finding probability. We characterize this process and analyze its interactions with job creation and wage determination. Our theory sheds new light on how unemployment can affect workers' labor market outcomes and wage determination, providing a rational explanation for discouragement as the consequence of negative search outcomes. In particular, longer unemployment durations are likely to be followed by lower reemployment wages because a worker's beliefs about his job‐finding process deteriorate with unemployment duration. Moreover, our analysis provides a set of useful results on dynamic programming with optimal learning.     

信息技术投资降低搜索成本对市场的均衡分析

根据产品空间差异模型 ,应用博弈论的均衡理论 ,分析了在销售商不进行合谋或没有市场垄断力量的情况下 ,销售商投资信息技术以后 ,引起消费者搜索成本降低对销售商产生的不同影响 :销售商无论作为个体还是整体 ,其利润收益值都降低 .但是 ,对信息技术投资力度大并使消费者搜索成本降低得更多的销售商 ,则可扩大市场占有率和提高市场竞争力 ,因此销售商具有投资激励 .分析了销售商在降低搜索成本后的对应策略 .搜索成本降低尽管减少了销售商利润 ,但能提高消费者和整个社会的福利水平 .分析了当消费者搜索成本降低到极限时 ,市场处于一种最优的古典竞争均衡状态 ,价格等于边际成本 ,销售商利润为零 ,消费者占有完全剩余 .分析和解释了信息技术生产率悖论问题