Optimal keyword bidding in search-based advertising with target exposure levels

Search-based advertising has become very popular since it provides advertisers the ability to attract potential customers with measurable returns. In this type of advertising, advertisers bid on keywords to have an impact on their ad’s placement, which in turn affects the response from potential customers. An advertiser must choose the right keywords and then bid correctly for each keyword in order to maximize the expected revenue or attain a certain level of exposure while keeping the daily costs in mind. In response to increasing need for analytical models that provide a guidance to advertisers, we construct and examine deterministic optimization models that minimize total expected advertising costs while satisfying a desired level of exposure. We investigate the relationship between our problem and the well-known continuous non-linear knapsack problem, and then solve the problem optimally by utilizing Karush–Kuhn–Tucker conditions. We present practical managerial insights based on the analysis of both a real-life data from a retailer and a hypothetical data.     

Market oscillations induced by the competition between value-based and trend-based investment strategies

We consider financial market using mathematical models which incorporate an excess demand function that depends not only upon the price but on the price derivative. The classical (value-based) motivation for purchasing the equity is augmented with a trend-based strategy of buying due to rising prices. An analysis (based on money flow and the finiteness of assets) of the supply, demand and price as a function of time leads to a system of ordinary differential equations which is mathematically complete. The numerical study of our equations exhibits overshooting, abrupt reversals and oscillations in prices. We examine our models within the context of real markets and economic laboratory experiments by comparing its predictions with a set of Porter and Smith experiments and with all US stock market “crashes” since 1929.     

Risk management in power markets: The Hedging value of production flexibility

Since the 1990s power markets are being restructured worldwide and nowadays electrical power is traded as a commodity. The liberalization and with it the uncertainty in gas, fuel and electrical power prices requires an effective management of production facilities and financial contracts. Thereby derivatives build essential instruments to exchange volume as well as price risks. The challenge for participants in the newly competitive market environment is how to design, price and hedge derivative contracts in particular combination with the flexibility embedded in dispatch strategies of production assets. Accordingly, an adequate basis for management and investment decisions is needed which responds to the highly complex market situation.     

Portfolio Optimization in a Semi-Markov Modulated Market

We address a portfolio optimization problem in a semi-Markov modulated market. We study both the terminal expected utility optimization on finite time horizon and the risk-sensitive portfolio optimization on finite and infinite time horizon. We obtain optimal portfolios in relevant cases. A numerical procedure is also developed to compute the optimal expected terminal utility for finite horizon problem. This work was supported in part by a DST project: SR/S4/MS: 379/06; also supported in part by a grant from UGC via DSA-SAP Phase IV, and in part by a CSIR Fellowship.     

基金“拥挤交易”对A股股价泡沫的影响研究

随着基金数量的不断增加,多家基金重仓一只股票所呈现的“拥挤交易”现象日渐明显。本文运用面板数据模型,对基金“拥挤交易”与A股股价泡沫之间的关系进行考察。结果表明,当公司超过6只基金重仓持股时,基金拥挤交易会对股价泡沫形成促进作用;当小于6只基金重仓持股时,这一关系则不显著。即:基金拥挤交易需要在“拥挤”到一定程度后才会促进股价泡沫膨胀。因此,管理层应高度重视6家以上基金重仓持股的股票,这类股票往往会形成较大的泡沫,同时也存在较大的崩溃风险。另外,管理层还应审慎研究政策出台时可能带来的预期,最大限度的避免基金经理产生一致的信念和一致行动,降低基金拥挤交易现象的发生。     

The principle of the Internet evolving and the conjecture of the optimal structure of Internet

In this paper we will give the statistical characteristics and general principles of an optimal structure of the Internet, which is a scale-free network. Since the purpose of the Internet is to allow fast and easy communication, the average path length is used to measure the performance of the network, and the number of edges of the network is used as a metric of its cost. Based on this, the goal of this Internet optimization problem is to obtain the highest performance with the lowest cost. A multi goal optimization problem is proposed to model this problem. By using two empirical formulas of and , we are able to find the statistical characteristics of the optimal structure. There is a critical power law exponent α _c for the Internet with power law degree distribution, at which the Internet can obtain a relatively good performance with a low cost. We find that this α _c is approximately 2.1.     

促进网络投资的互联网骨干网互联结算规制改革研究

本文研究结果表明,不管是上游市场处于垄断还是存在多家骨干网竞争情形,无互联结算规制下的网络投资量大于互联结算规制下的网络投资量,并且此时的社会福利也大于互联结算规制下的社会福利。因此,为促进骨干网市场的网络投资,应充分发挥市场机制在互联结算中的调节作用,同时要在上游市场引入竞争机制,让新的竞争者参与竞争。     

我国创业板企业内部人交易择时行为研究

利用深圳证券交易所2012年1月1日至2013年12月31日期间的创业板企业内部人的交易数据,从间接与直接两个角度考虑创业板企业的内部人交易与信息优势利用的关系.从间接角度来看,创业板企业的内部人卖出能够有效预测未来股票走势,来获取超额收益;而买入则不具有显著的择时能力,不能获取正的超额收益,这与主板企业具有相同特点;但其中创业板小额买入可取得长期收益,这与主板企业有所不同.从直接角度来看,创业板企业内部人在卖出中充分利用了估值判断优势,抓住高估值偏差的市场机会套现,这与主板企业的特点相同;而创业板企业的内部人买入交易决策与估值判断、业绩预测这两种信息优势利用的关系都不密切,这与主板企业的特点有所不同.     

Alternative optimality criteria of portfolio selection based upon threshold stopping rule

This paper proposes two types of alternative criteria of optimality for the continuous time portfolio selection problem. The optimality criteria, the so–called Laplace–Stieltjes transform (LST) criteria, are based on the assumption that the financial agent has a target level for the wealth accumulation process. These criteria are closely related to the so–called threshold stopping investment rule. We analytically derive the LST criteria and numerically compare them with the well–known Kelly criterion. It is shown that the portfolio strategies suggested may overcome the problem that the growth portfolio is often overestimated in several investment situations.     

Obtaining test problems via Internet

In this paper we detail a number of sources of test problems accesible via Internet. We also outline a number of ways by which such test problems can be obtained, for example by electronic mail (email), anonymous file transfer protocol (anonymous ftp), Gopher, Veronica and via the World Wide Web (WWW) using browsers such as Mosaic and Netscape.