Tragedy of the commons in online social search

Online social search (OSS) brings forth a new way to harness the Internet for answers. In this paper, we study the non-cooperation problem in OSS. We propose an analytical model that captures the behavior of OSS nodes, and, from a gaming-strategy point of view, analyze various strategies an individual node can utilize to allocate its awareness capacity. Based on this we derive the Pareto inefficiency in terms of the system cost. We also propose an incentive scheme under which the optimal state of individual nodes is also optimal for the whole system. Extensive simulations show that the strategy under our proposed incentive mechanism outperforms other strategies in terms of the system cost and the search success rate. To the best of our knowledge, this is the first study of the tragedy-of-the-commons problem in OSS. © 2011 IEEE.published_or_final_versionThe 2011 IEEE International Conference on Communications (ICC 2011), Kyoto, Japan, 5-9 June 2011. In Proceedings of ICC 2011, 2011, p. 1-

The Logic of Reciprocity: Trust, Collective Action, and Law

The Logic of Collective Action has for decades supplied the logic of public-policy analysis. In this pioneering application of public choice theory, Mancur Olson elegantly punctured the premise - shared by a variety of political theories - that individuals can be expected to act consistently with the interest of the groups to which they belong. Absent externally imposed incentives, wealth-maximizing individuals, he argued, will rarely find it in their interest to contribute to goods that benefit the group as a whole, but rather will free ride on the contributions that other group members make. As a result, too few individuals will contribute sufficiently, and the well-being of the group will suffer. These assumptions dominate public-policy analysis and public policy itself across a host of regulatory domains - from tax collection to environmental conservation, from street-level policing to policing of the internet. But as a wealth of social science evidence now makes clear, Olson\u27s Logic is false. In collective-action settings, individuals adopt not a materially calculating posture but rather a richer, more emotionally nuanced reciprocal one. When they perceive that others are behaving cooperatively, individuals are moved by honor, altruism, and like dispositions to contribute to public goods even without the inducement of material incentives. When, in contrast, they perceive that others are shirking or otherwise taking advantage of them, individuals are moved by resentment and pride to withhold their own cooperation and even to engage in personally costly forms of retaliation

Ігрова модель взаємодії користувачів у гетерогенних розподілених середовищах

В даній роботі досліджується ігрова модель взаємодії користувачів, що виконують паралельні обчислення у гетерогенній багатопроцесорній системі. Запропонований підхід моделювання застосовується до задачі множення матриць з планувальником мін-мін. Дією користувачів у даному випадку є розмір блоку на яку розрізається матриця. Експериментально отримані характеристики системи були використані для налаштування імітаційної моделі, що дозволило виміряти оцінку часу завершення роботи для всіх можливих комбінацій розбиття задач по процесорам та побудувати поверхню залежності часу закінчення роботи для кожного користувача. Отримані результати були обґрунтовані і узагальнені на базі ігрового підходу, зокрема, показано існування точки рівноваги Неша для взаємодії двох користувачів та знайдені умови її Парето неефективності

Energy Efficient Cooperative Communication

This dissertation studies several problems centered around developing a better understanding of the energy efficiency of cooperative wireless communication systems. Cooperative communication is a technique where two or more nodes in a wireless network pool their antenna resources to form a virtual antenna array . Over the last decade, researchers have shown that many of the benefits of real antenna arrays, e.g. spatial diversity, increased range, and/or decreased transmission energy, can be achieved by nodes using cooperative transmission. This dissertation extends the current body of knowledge by providing a comprehensive study of the energy efficiency of two-source cooperative transmission under differing assumptions about channel state knowledge, cooperative protocol, and node selfishness. The first part of this dissertation analyzes the effect of channel state information on the optimum energy allocation and energy efficiency of a simple cooperative transmission protocol called orthogonal amplify-and-forward (OAF). The source nodes are required to achieve a quality-of service (QoS) constraint, e.g. signal to noise ratio or outage probability, at the destination. Since a QoS constraint does not specify a unique transmit energy allocation when the nodes use OAF cooperative transmission, minimum total energy strategies are provided for both short-term and long-term QoS constraints. For independent Rayleigh fading channels, full knowledge of the channel state at both of the sources and at the destination is shown to significantly improve the energy efficiency of OAF cooperative transmission as well as direct (non-cooperative) transmission. The results also demonstrate how channel state knowledge affects the minimum total energy allocation strategy. Under identical channel state knowledge assumptions, the results demonstrate that OAF cooperative transmission tends to have better energy efficiency than direct transmission over a wide range of channel conditions. The second part of this dissertation focuses on the development of an opportunistic hybrid cooperative transmission protocol that achieves increased energy efficiency by not only optimizing the resource allocation but also by selecting the most energy efficient cooperative transmission protocol from a set of available protocols according to the current channel state. The protocols considered in the development of the hybrid cooperative transmission protocol include compress-and-forward (CF), estimate-and-forward (EF), non-orthogonal amplify-and-forward (NAF), and decode-and-forward (DF). Instantaneous capacity results are analyzed under the assumption of full channel state knowledge at both of the sources and the destination node. Numerical results are presented showing that the delay limited capacity and outage probability of the hybrid cooperative transmission protocol are superior to that of any single protocol and are also close to the cut-set bound over a wide range of channel conditions. The final part of this dissertation focuses on the issue of node selfishness in cooperative transmission. It is common to assume in networks with a central authority, e.g. military networks, that nodes will always be willing to offer help to other nodes when requested to do so. This assumption may not be valid in ad hoc networks operating without a central authority. This section of the dissertation considers the effect selfish behavior on the energy efficiency of cooperative communication systems. Using tools from non-cooperative game theory, a two-player relaying game is formulated and analyzed in non-fading and fading channel scenarios. In non-fading channels, it is shown that a cooperative equilibrium can exist between two self-interested sources given that the end of the cooperative interaction is uncertain, that the sources can achieve mutual benefit through cooperation, and that the sources are sufficiently patient in the sense that they value future payoffs. In fading channels, a cooperative conditional trigger strategy is proposed and shown to be an equilibrium of the two-player game. Sources following this strategy are shown to achieve an energy efficiency very close to that of a centrally-controlled system when they are sufficiently patient. The results in this section show that cooperation can often be established between two purely self-interested sources without the development of extrinsic incentive mechanisms like virtual currency

Towards Trustworthy, Efficient and Scalable Distributed Wireless Systems

Advances in wireless technologies have enabled distributed mobile devices to connect with each other to form distributed wireless systems. Due to the absence of infrastructure, distributed wireless systems require node cooperation in multi-hop routing. However, the openness and decentralized nature of distributed wireless systems where each node labors under a resource constraint introduces three challenges: (1) cooperation incentives that effectively encourage nodes to offer services and thwart the intentions of selfish and malicious nodes, (2) cooperation incentives that are efficient to deploy, use and maintain, and (3) routing to efficiently deliver messages with less overhead and lower delay. While most previous cooperation incentive mechanisms rely on either a reputation system or a price system, neither provides sufficiently effective cooperation incentives nor efficient resource consumption. Also, previous routing algorithms are not sufficiently efficient in terms of routing overhead or delay. In this research, we propose mechanisms to improve the trustworthiness, scalability, and efficiency of the distributed wireless systems. Regarding trustworthiness, we study previous cooperation incentives based on game theory models. We then propose an integrated system that combines a reputation system and a price system to leverage the advantages of both methods to provide trustworthy services. Analytical and simulation results show higher performance for the integrated system compared to the other two systems in terms of the effectiveness of the cooperation incentives and detection of selfish nodes. Regarding scalability in a large-scale system, we propose a hierarchical Account-aided Reputation Management system (ARM) to efficiently and effectively provide cooperation incentives with small overhead. To globally collect all node reputation information to accurately calculate node reputation information and detect abnormal reputation information with low overhead, ARM builds a hierarchical locality-aware Distributed Hash Table (DHT) infrastructure for the efficient and integrated operation of both reputation systems and price systems. Based on the DHT infrastructure, ARM can reduce the reputation management overhead in reputation and price systems. We also design a distributed reputation manager auditing protocol to detect a malicious reputation manager. The experimental results show that ARM can detect the uncooperative nodes that gain fraudulent benefits while still being considered as trustworthy in previous reputation and price systems. Also, it can effectively identify misreported, falsified, and conspiratorial information, providing accurate node reputations that truly reflect node behaviors. Regarding an efficient distributed system, we propose a social network and duration utility-based distributed multi-copy routing protocol for delay tolerant networks based on the ARM system. The routing protocol fully exploits node movement patterns in the social network to increase delivery throughput and decrease delivery delay while generating low overhead. The simulation results show that the proposed routing protocol outperforms the epidemic routing and spray and wait routing in terms of higher message delivery throughput, lower message delivery delay, lower message delivery overhead, and higher packet delivery success rate. The three components proposed in this dissertation research improve the trustworthiness, scalability, and efficiency of distributed wireless systems to meet the requirements of diversified distributed wireless applications

Coopetition (Contemporaneous Cooperation and Competition) Among Nonprofit Arts Organizations: The Case of Symphony Orchestras

Coopetition was formalized as a strategic management concept in the early 1990s by Ray Noorda, CEO of Novell, who coined the term and proposed that often, in order to achieve growth in an organization or industry, You have to cooperate and compete at the same time (Davis 1993). Although the individual ideas of cooperation and competition in the business environment have been well-established for some time, the formal idea of contemporaneous cooperation and competition, or cooperation among competitors, is relatively new in business and academic literature. Why is this hybrid concept important? The literature to date on coopetition and its antecedents suggests that they constitute a phenomenon that extends beyond the individual paradoxical constructs of competition and cooperation (Chen 2002). In a business environment that has historically stressed competitive advantage, the assertion that the best strategy often has multiple winners is a powerful one (Brandenburger and Nalebuff 1996). This research expands the concept of coopetition to an area in which it has not yet been studied: the nonprofit arts sector. It provides a comprehensive literature review, a posited model of coopetition and related hypotheses, and two proposed studies: a qualitative exploratory study to examine coopetition in the nonprofit arts setting, and a quantitative study to empirically assess the model and hypotheses. Contributions of this research include: (1) an in-depth literature review of the first ten years of theoretical and empirical research on the concept of coopetition, (2) a literature review of the concepts of competition and cooperation in the context of the nonprofit arts environment, (3) presentation of a conceptual framework of coopetition in the nonprofit arts environment and related hypotheses based on the literature, and (4) qualitative and quantitative studies of the concept of coopetition in a nonprofit arts setting and a resulting understanding of how nonprofit arts coopetition in artistic, operational, marketing, and fund development contexts has the potential to impact organizational improvement in terms of participant organizational financial performance and organizational effectiveness. From an academic standpoint, this research adds to the literature in the areas of nonprofit marketing/management and coopetition/strategic management. From a nonprofit arts management and marketing standpoint, the qualitative and quantitative studies indicate that the range of potential strategic and tactical options for achieving organizational improvement is broader than traditionally contemplated, with opportunities that can be envisioned and leveraged through coopetition

How does regulation affect innovation and technology change in the water sector in England and Wales?

This thesis examines the role of regulation in technological change in the water sector in England and Wales. Based on a combination of Social-Ecological Systems (SES) theory and the Multi-Level Perspective on technological transitions a Comparative Information-Graded Approach (CIGA) is developed in Part 1. As part of the CIGA, a series of tools is used for characterizing and evaluating the relationship between regulation and technology. In Part 2, the CIGA is applied to characterize the relationship between regulation and water innovation in England and Wales based on official publications, Environment Agency data, and interviews. In particular, 7 mechanisms are identified by which regulation affects innovation and 5 issues of trust negatively interact with innovation. As trust is established through these mechanisms, opportunities for innovation are at times sacrificed. Part 3 develops and analyses a set of models based on findings in Part 2. Dynamical systems and fictitious play analysis of a trustee game model of regulation exhibits cyclicality providing an explanation for observed cycles which create an inconsistent drive for innovation. Trustee and coordination models are evaluated in Chapter 7 highlighting how most tools struggle with the issue of technological lock-in. Chapter 8 develops a model of two innovators and a public good water technology over time, showing the role foresight plays in this context as well as the disincentive to develop it. Taken together, the CIGA characterization and modelling work provide a series of recommendations and insights into how the system of regulation affects technology change.Open Acces