Time Changes for Lévy Processes

The goal of this paper is to consider pure jump Lévy processes of finite variation with an infinite arrival rate of jumps as models for the logarithm of asset prices. These processes may be written as time-changed Brownian motion. We exhibit the explicit time change for each of a wide class of Lévy processes and show that the time change is a weighted price move measure of time. Additionally, we present a number of Lévy processes that are analytically tractable, in their characteristic functions and Lévy densities, and hence are relevant for option pricing.     

MARKOWITZ'S PORTFOLIO OPTIMIZATION IN AN INCOMPLETE MARKET

In this paper, for a process S , we establish a duality relation between K_p , the     - closure of the space of claims in     , which are attainable by "simple" strategies, and     , all signed martingale measures     with     , where   p ≥ 1, q ≥ 1  and     . If there exists a     with     a.s., then K_p consists precisely of the random variables     such that ϑ is predictable S -integrable and     for all     . The duality relation corresponding to the case   p = q = 2  is used to investigate the Markowitz's problem of mean–variance portfolio optimization in an incomplete market of semimartingale model via martingale/convex duality method. The duality relationship between the mean–variance efficient portfolios and the variance-optimal signed martingale measure (VSMM) is established. It turns out that the so-called market price of risk is just the standard deviation of the VSMM. An illustrative example of application to a geometric Lévy processes model is also given.     

A Multi-Agent View of Strategic Planning Using Group Support Systems and Artificial Intelligence

The strategic planning process is dynamic and complex. Including a Group Support System (GSS) in the problem-solving process can improve the content quality of the strategic plan by allowing increased participation by more members of the organization. However, it can also add to the complexity of the problem by increasing the quantity of textual information that can result from group activity. Added complexity increases cognitive overload and frustrations of those participants negotiating the contents of the strategic plan. This article takes a multi-agent view of the strategic planning process. It considers group participants as multiple agents concerned with the content quality of the strategic plan. The facilitator agent is responsible for guiding groups in the strategic plan construction process as well as for solving process problems such as cognitive overload. We introduce an AI Concept Categorizer agent, a software tool that supports the facilitator in addressing the process problem of cognitive overload associated with convergent group activities by synthesizing group textual output into conceptual clusters. The implementation of this tool reduces frustrations which groups encounter in the process of classifying textual output and provides more time for discussion of the concepts themselves. Because of the large amount of convergent activity necessary for strategic planning, the addition of the AI Concept Categorizer to the strategic planning process should increase the quality of the strategic plan and the buy-in of the participants in the strategic planning process.     

Under the influence of the team? An investigation of the relationships between team autonomy,individual autonomy and social influence within teams

This study contributes to the debate about whether teamwork facilitates or constrains the single team member's autonomy at work. We investigate whether team autonomy can explain employees' individual autonomy, the teams' informal influence on its members and employees' desire for either individual or team influence. Questionnaire data were collected among employees in four Danish companies from different industries with various types of team organization: permanent, project-based and mixed teams. The results of the multiple regression analyses show that team autonomy is positively associated with individual autonomy, which is neither moderated by the team's ability to make the employee feel responsible nor by team support. Team autonomy is positively associated with facilitative social influence, i.e. team reward, team support and we find a negative association between team autonomy and team coercion. Moreover, employees who experienced more team than individual autonomy wanted their teams to control more work issues compared to employees who experienced lower team than individual autonomy.     

基于随机过程理论的复杂可修系统可靠性规律研究

利用随机过程理论研究了复杂可修系统的可靠性规律,用随机过程模型中的Ｗｅｉｂｕｌｌ过程来描述复杂可修系统的可靠性规律。用Ｍｏｎｔｅ Ｃａｒｌｏ方法模拟验证了Ｗｅｉｂｕｌｌ过程模型的参数估计公式。其中参数β的最大似然估计误差低于２％,λ的最大似然估计误差低于７％。两组试验数据的处理结果表明Ｗｅｉｂｕｌｌ过程模型有较高的拟合精度。     

CONSTANT PROPORTION PORTFOLIO INSURANCE IN THE PRESENCE OF JUMPS IN ASSET PRICES

Constant proportion portfolio insurance (CPPI) allows an investor to limit downside risk while retaining some upside potential by maintaining an exposure to risky assets equal to a constant multiple of the cushion , the difference between the current portfolio value and the guaranteed amount. Whereas in diffusion models with continuous trading, this strategy has no downside risk, in real markets this risk is nonnegligible and grows with the multiplier value. We study the behavior of CPPI strategies in models where the price of the underlying portfolio may experience downward jumps. Our framework leads to analytically tractable expressions for the probability of hitting the floor, the expected loss, and the distribution of losses. This allows to measure the gap risk but also leads to a criterion for adjusting the multiplier based on the investor's risk aversion. Finally, we study the problem of hedging the downside risk of a CPPI strategy using options. The results are applied to a jump-diffusion model with parameters estimated from returns series of various assets and indices.     

QUADRATIC TERM STRUCTURE MODELS FOR RISK-FREE AND DEFAULTABLE RATES

In this paper, quadratic term structure models (QTSMs) are analyzed and characterized in a general Markovian setting. The primary motivation for this work is to find a useful extension of the traditional QTSM, which is based on an Ornstein–Uhlenbeck (OU) state process, while maintaining the analytical tractability of the model. To accomplish this, the class of quadratic processes, consisting of those Markov state processes that yield QTSM, is introduced. The main result states that OU processes are the only conservative quadratic processes. In general, however, a quadratic potential can be added to allow QTSMs to model default risk. It is further shown that the exponent functions that are inherent in the definition of the quadratic property can be determined by a system of Riccati equations with a unique admissible parameter set. The implications of these results for modeling the term structure of risk-free and defaultable rates are discussed.     

The Ethical Dimensions of Decision Processes of Employees

The influence of stakeholders, organisational commitment, personal values, goals of the organisation and socio-demographic characteristics of individuals on the ethical dimension of behavioural intentions of employees in various organisations are investigated. The research results show that employees working for the public sector or in educational institutions take more ethical aspects into account than employees working in the "private" sector. The influence of stakeholders and organisational commitment do not significantly affect the ethical behaviour of employees, and only some personal values and goals of the organisation have a significant influence on ethical behaviour. The most significant explanatory factor of ethical decision making seems to be what may be called "stage in the career of the employee": "ethical" employees can be described as young, with a relatively low income, limited work experience and a low level of responsibility in the company.