Uncoordinated frequency hopping (UFH) has recently emerged as an effective mechanism to defend against jamming attacks. Existing research focuses on the optimal design of the hopping pattern, which implicitly assumes that the strategy of the attacker is fixed. In practice, the attacker might adjust its strategy to maximize its damage on the communication system. In this thesis, we study the design of optimal hopping pattern (the defense strategy) as long as the optimal jamming pattern (the attack strategy). In particular, we model the dynamic between the legitimate users and the attacker as a zero sum game, and study the property of this game. We show that when the legitimate users and the jammer can access only one channel at any time, the game has a unique Nash equilibrium. In the Nash equilibrium, the legitimate users and Eve will access or jam only a subset of channels that have good channel quality. Furthermore, the better the channel, the larger the probability that Eve will jam the channel and the smaller the probability the legitimate users will access this channel. We further extend the study to multiple access multiple jamming case and characterize the Nash equilibrium. We also give numerical results to illustrate the analytical results derived in this thesis.

Machinery investments represent a substantial portion of agribusiness firms’ costs. Because of high machinery costs, variable profit margins, and increasing competition, agribusiness managers continually seek methods to maintain profitability and manage risk. One relatively new method is jointly owning and sharing machinery. Contract design issues to enhance horizontal linkages between firms through machinery sharing are addressed. Specifically, costs and depreciation sharing between two firms entering into a joint machinery ownership contract are examined. Two, two-player models, a Nash equilibrium game theoretical model and an applied two-farm simulation model are used to determine impacts of machinery sharing on firms engaged in machinery sharing. The Nash equilibrium model determines theoretical optimal sharing rules for two generic firms. Using the Nash equilibrium model as the basis, the two-farm simulation model provides more specific insights into joint harvest machinery sharing. Both models include contractual components that are uniquely associated with machinery sharing. Contractual components include penalty payment structure for untimely machinery delivery and the percentages of shared costs paid and depreciation claimed paid by each firm. Harvesting windows for each farm and yield reductions associated with untimely machinery delivery are accounted for within the models. Machinery sharing can increase the NPV of after tax cash flows and potentially reduce risk. Sharing will, however, not occur if own marginal transaction costs and/or marginal penalty costs associated with untimely machinery delivery are too large. Further, if the marginal costs of sharing are small relative to own marginal net benefits, sharing will not occur. There are potential tradeoffs between the percentage of shared costs paid and the percentage of shared depreciation claimed depending on each farms’ specific tax deductions. Harvesting window overlaps help determine the viability of machinery sharing. Farms may be better off sharing larger, more efficient machinery than using smaller machinery even when harvest must be delayed. Percentages of shared costs, depreciation, and tax deductions have important tax implications that impact the after tax cash flows and should be considered when negotiating machinery sharing contracts.

No description available.

It is known that quantum strategies change the range of possible payoffs for the players in the prisoner's dilemma. In this paper, we examine the effect of the degree of entanglement in determining the payoffs. When both players play quantum strategies, we show that the payoff for both players is unaffected by the entanglement value and it leads to a new Nash equilibrium.

Increasingly used in online auctions, buyout prices allow bidders to instantly purchase the item listed. We distinguish two types: a temporary buyout option disappears if a bid above the reserve price is made; a permanent one remains throughout the auction or until it is exercised. In a model featuring time-sensitive bidders with uniform valuations and Poisson arrivals but endogenous bidding times, we focus on finding temporary and permanent buyout prices maximizing the seller's discounted revenue, and examine the relative benefit of using each type of option in various environments. We characterize equilibrium bidder strategies in both cases and then solve the problem of maximizing seller's utility by simulation. Our numerical experiments suggest that buyout options may significantly increase a seller’s revenue. Additionally, while a temporary buyout option promotes early bidding, a permanent option gives an incentive to the bidders to bid late, thus leading to concentrated bids near the end of the auction. / Singapore-MIT Alliance (SMA)

No description available.

For zero-sum games, we have efficient solution techniques. Unfortunately, there are interesting games that are too large to solve. Here, a popular approach is to solve an abstract game that models the original game. We assume that more accurate the abstract games result in stronger strategies. There is substantial evidence to support this assumption. We begin by formalizing abstraction and refinement, a notion of expressive power for abstractions. We then show the assumption fails to hold under two criteria. The first is exploitability, which measures performance in the worst-case. The second is called the domination value, which measures how many mistakes a strategy makes. Despite these pathologies, we notice that larger strategies tend to make fewer mistakes and perform better in tournaments. Finally, we introduce strategy grafting, a technique that uses sub-game decomposition, which allow us to create good strategies in much larger spaces than previously possible.

Master of Science / Electrical and Computer Engineering / Sanjoy Das / Groundwater is one of the most vital of all common pool resources throughout the world. More than half of groundwater is used to grow crops. This research models groundwater depletion patterns within a multi-agent system framework. Irrigators are modeled as agents in the multi-agent system. The irrigation strategies adopted by the agents are investigated using game theory, under several futuristic scenarios. The consequence of unregulated groundwater extraction in each case is analyzed. A set of five irrigators, growing three crops: corn, sorghum and wheat, have been considered in this study. To allow groundwater flow, these agents are assumed to be located in adjoining farm lands. Irrigators are modeled selfish agents that strategize their irrigation patterns in order to maximize their own utilities, i.e. the difference between the total revenue obtained from crop sales and the costs incurred, including groundwater extraction costs. Due to groundwater flow, irrigators have no incentive to conserve groundwater for later use. This leads to unsustainable depletion of the resource. Using the Nikaido-Isoda relaxation algorithm, their irrigation strategies under Nash equilibrium, when no irrigator can increase its utility by unilaterally changing its strategy, are obtained. All parameters in this research are representative of Kansas. Recorded environmental and economic data of the region, along with the DSSAT software, have been used to obtain these futuristic projections. These scenarios include temperature increase, lowering of the water table, different precipitation levels, and different price increases for the crops. One of the emergent phenomena of the simulations is the adoption of crop rotation patterns by the irrigators to conserve groundwater. The irrigators grow corn, which is a more profitable yet water intensive crop in one year, and in the next, conserve water by growing sorghum instead. Another emergent outcome of this research is the viability of LEMAs. When the irrigators are subject to LEMA-level limits on groundwater use, there is a slight increase in the aggregate utility of the LEMA

The Internet has a loosely hierarchical structure. At the top of the hierarchy are the backbones, also called Internet Access Providers (hereafter IAPs). The second layer of the hierarchy is comprised of Internet Service Providers (hereafter ISPs). At the bottom of the hierarchy are the end users, consumers, who browse the web, and websites. To provide access to the whole Internet, the providers must interconnect with each other and share their network infrastructure. Two main forms of interconnection have emerged — peering under which the providers carry each other's traffic without any payments and transit under which the downstream provider pays the upstream provider a certain settlement payment for carrying its traffic. This dissertation develops three game theoretical models to describe the interconnection agreements among the providers, and analysis of those models from two alternative modeling perspectives: a purely non-cooperative game and a network perspective. There are two original contributions of the dissertation. First, we model the formation of peering/transit contracts explicitly as a decision variable in a non-cooperative game, while the current literature does not employ such modeling techniques. Second, we apply network analysis to examine interconnection decisions of the providers, which yields much realistic results. Chapter 1 provides a brief description of the Internet history, architecture and infrastructure as well as the economic literature. In Chapter 2 we develop a model, in which IAPs decide on private peering agreements, comparing the benefits of private peering relative to being connected only through National Access Points (hereafter NAPs). The model is formulated as a multistage game. Private peering agreements reduce congestion in the Internet, and so improve the quality of IAPs. The results show that even though the profits are lower with private peerings, due to large investments, the network where all the providers privately peer is the stable network. Chapter 3 discusses the interconnection arrangements among ISPs. Intra-backbone peering refers to peering between ISPs connected to the same backbone, whereas inter-backbone peering refers to peering between ISPs connected to different backbones. We formulate the model as a two-stage game. Peering affects profits through two channels - reduction of backbone congestion and ability to send traffic circumventing congested backbones. The relative magnitude of these factors helps or hinders peering. In Chapter 4 we develop a game theoretic model to examine how providers decide who they want to peer with and who has to pay transit. There is no regulation with regard to interconnection policies of providers, though there is a general convention that the providers peer if they perceive equal benefits from peering, and have transit arrangements otherwise. The model discusses a set of conditions, which determine the formation of peering and transit agreements. We argue that market forces determine the terms of interconnection, and there is no need for regulation to encourage peering. Moreover, Pareto optimum is achieved under the transit arrangements. / Ph. D.

Denna kandidatuppsats bemöter frågan om väljarbeteende i allmänna val; huruvida strategiskt röstande (taktikröstning) är ett förekommande fenomen i val till svenska kommunfullmäktige eller ej och i så fall vilka faktorer som ligger bakom strategiskt röstande. En underförstådd tes bakom väljarbeteende är att röstberättigade röstar i enlighet med deras partipreferens utifrån en rad underliggande orsaker, såsom sakpolitik, partifärg, ideologi och organisationsstruktur. Dock har viss forskning uppstått som tyder på att somliga väljare agerar konsekvent och röstar utifrån bästa möjliga utdelning (payoff), snarare än direkta skäl. Dessa indirekta skäl kan röra sig om partiernas valallianser med övriga partier, något som alltid inte uppskattas av väljarna. Under senare halvan av 1900-talet har studier kring väljarbeteende uppmärksammats av statsvetare och beteendevetare. En av de mest omnämnda publikationerna inom vetenskapen är undertecknad den amerikanska ekonomen Anthony Downs som genom sin bok An Economic Theory of Democracy (1957) har undersökt relationen mellan politiska kandidater och väljare. Uppsatsen kommer presentera för läsaren tidigare studier inom detta specifika forskningsområde samt en nutidshistorisk överblick i s.k. oheliga allianser. Resultatet kommer visa på partisamverkans tydliggjorda betydelse i hur kommunmedborgarna röstar i allmänna val.