Search and planning under incomplete information : a study using Bridge card play

This thesis investigates problem-solving in domains featuring incomplete information and multiple agents with opposing goals. In particular, we describe Finesse --- a system that forms plans for the problem of declarer play in the game of Bridge. We begin by examining the problem of search. We formalise a best defence model of incomplete information games in which equilibrium point strategies can be identified, and identify two specific problems that can affect algorithms in such domains. In Bridge, we show that the best defence model corresponds to the typical model analysed in expert texts, and examine search algorithms which overcome the problems we have identified. Next, we look at how planning algorithms can be made to cope with the difficulties of such domains. This calls for the development of new techniques for representing uncertainty and actions with disjunctive effects, for coping with an opposition, and for reasoning about compound actions. We tackle these problems with a..

Application of Game Theory in Studying Subcontractors’ Cooperation in Construction Projects - Joint Resource Management

Resource management is one of the most significant roles of every project manager in today’s highly competitive construction industry. One solution to reduce costs of resources is to manage them jointly. Joint resource management is based on cooperation between subcontractors who are seeking a win-win resolution. It is an attempt to schedule the project tasks, enabling subcontractors to optimally utilize resources and minimize their idle times. Cooperative game theory, describing a series of moves leading to an integrative conclusion, is a powerful tool for studying cooperation between subcontractors. Construction projects are not too different from real games. By using game theoretic language, a construction project is defined as a “game” in which subcontractors are considered as game “players” and are able to manage their own resources to maximize their “profit”. Talking of cooperative game theory, these players develop strategies to maximize the overall profit of project based on the fact that these strategies would bring more profit to each player too. Cooperative game theory is used to analyze interactions between subcontractors to allocate the game profit among the players. In order to achieve this, subcontractors should have a clear understanding of cooperation and understand mutual objectives to provide a sound basis for a synergistic climate in joint resource management. One key point in understanding cooperation is trust. Trust is known as one of the fundamental principles of cooperation. It can lead to a cooperative behavior between subcontractors and act as the glue holding subcontractors together. Trust is defined as a psychological state comprising the intention to accept vulnerability based upon positive expectations of the intentions or behavior of another. “Trust” game (also known as “stag hunt”) as well as “Prisoner’s Dilemma”, have been used to represent trust and cooperation problem in the game theoretic framework. Compared to what has been done in other areas, less attention has been given to trust in construction projects. With all these in mind, the main purpose of this study is to study the cooperation between subcontractors employing cooperative game theory. After reviewing the theoretical foundations of game theory and in light of previous studies done, a model is constructed with the aim of optimizing common resources. The gains of joint resource management are analyzed and allocated by applying the cooperative game solution. A case study is also used to analyze the problem and illustrate the model’s practical contribution to construction projects. Last but not least, the cooperation game is studied utilizing the stag-hunt game, and a set of strategies to achieve the best outcomes in cooperation is offered

Programming Language Requirements for Human Communication Structures or Computer Conferencing

Our overall goal is to be able, simply and quickly, to construct computer conferencing systems for new requirements, applications, and even experimental ideas or fantasies. One way to view this requirement is as the creation of a highly parameterized conferencing system itself. Our view, however, is that of a programming language; i.e., an integrated notational system for the specification of communication structures and the associated actions or computation to be taken by the computer system hosting the structure. A communication structure consists of a group of people (and storage devices) each endowed with some characteristics, and some means of person-to-person communication. We view the expression of such structure as a set of rules, R (a,b,c), that expresses the actions to be performed in case a participant of characteristics -a sends a communication of type –b to a participant (or set) of characteristics -c. These rules and characteristics may change over time -- a dynamic structure. The new language to be developed must be able to express the formation of these rules (the details can be supported, of course, by existing coding systems). It must support the organization of such a scheme of dynamic rules. This Report details the consideration (and examples) for such a language that we have unearthed in our studies

Quantum Proofs

Quantum information and computation provide a fascinating twist on the notion of proofs in computational complexity theory. For instance, one may consider a quantum computational analogue of the complexity class \class{NP}, known as QMA, in which a quantum state plays the role of a proof (also called a certificate or witness), and is checked by a polynomial-time quantum computation. For some problems, the fact that a quantum proof state could be a superposition over exponentially many classical states appears to offer computational advantages over classical proof strings. In the interactive proof system setting, one may consider a verifier and one or more provers that exchange and process quantum information rather than classical information during an interaction for a given input string, giving rise to quantum complexity classes such as QIP, QSZK, and QMIP* that represent natural quantum analogues of IP, SZK, and MIP. While quantum interactive proof systems inherit some properties from their classical counterparts, they also possess distinct and uniquely quantum features that lead to an interesting landscape of complexity classes based on variants of this model. In this survey we provide an overview of many of the known results concerning quantum proofs, computational models based on this concept, and properties of the complexity classes they define. In particular, we discuss non-interactive proofs and the complexity class QMA, single-prover quantum interactive proof systems and the complexity class QIP, statistical zero-knowledge quantum interactive proof systems and the complexity class \class{QSZK}, and multiprover interactive proof systems and the complexity classes QMIP, QMIP*, and MIP*.Comment: Survey published by NOW publisher

An aesthetics of touch: investigating the language of design relating to form

How well can designers communicate qualities of touch? This paper presents evidence that they have some capability to do so, much of which appears to have been learned, but at present make limited use of such language. Interviews with graduate designer-makers suggest that they are aware of and value the importance of touch and materiality in their work, but lack a vocabulary to fully relate to their detailed explanations of other aspects such as their intent or selection of materials. We believe that more attention should be paid to the verbal dialogue that happens in the design process, particularly as other researchers show that even making-based learning also has a strong verbal element to it. However, verbal language alone does not appear to be adequate for a comprehensive language of touch. Graduate designers-makers’ descriptive practices combined non-verbal manipulation within verbal accounts. We thus argue that haptic vocabularies do not simply describe material qualities, but rather are situated competences that physically demonstrate the presence of haptic qualities. Such competencies are more important than groups of verbal vocabularies in isolation. Design support for developing and extending haptic competences must take this wide range of considerations into account to comprehensively improve designers’ capabilities

Rank-Order Tournaments as Optimum Labor Contracts

This paper analyzes compensation schemes which pay according to an individual's ordinal rank in an organization rather than his output level. When workers are risk neutral, it is shown that wages based upon rank induce the same efficient allocation of resources as an incentive reward scheme based on individual output levels. Under some circumstances, risk-averse workers actually prefer to be paid on the basis of rank. In addition, if workers are heterogeneous inability, low-quality workers attempt to contaminate high-quality firms, resulting in adverse selection. However, if ability is known in advance, a competitive handicapping structure exists which allows all workers to compete efficiently in the same organization.

New Game Physics - Added Value for Transdisciplinary Teams

This study focused on game physics, an area of computer game design where physics is applied in interactive computer software. The purpose of the research was a fresh analysis of game physics in order to prove that its current usage is limited and requires advancement. The investigations presented in this dissertation establish constructive principles to advance game physics design. The main premise was that transdisciplinary approaches provide significant value. The resulting designs reflected combined goals of game developers, artists and physicists and provide novel ways to incorporate physics into games. The applicability and user impact of such new game physics across several target audiences was thoroughly examined. In order to explore the transdisciplinary nature of the premise, valid evidence was gathered using a broad range of theoretical and practical methodologies. The research established a clear definition of game physics within the context of historical, technological, practical, scientific, and artistic considerations. Game analysis, literature reviews and seminal surveys of game players, game developers and scientists were conducted. A heuristic categorization of game types was defined to create an extensive database of computer games and carry out a statistical analysis of game physics usage. Results were then combined to define core principles for the design of unconventional new game physics elements. Software implementations of several elements were developed to examine the practical feasibility of the proposed principles. This research prototype was exposed to practitioners (artists, game developers and scientists) in field studies, documented on video and subsequently analyzed to evaluate the effectiveness of the elements on the audiences. The findings from this research demonstrated that standard game physics is a common but limited design element in computer games. It was discovered that the entertainment driven design goals of game developers interfere with the needs of educators and scientists. Game reviews exemplified the exaggerated and incorrect physics present in many commercial computer games. This “pseudo physics” was shown to have potentially undesired effects on game players. Art reviews also indicated that game physics technology remains largely inaccessible to artists. The principal conclusion drawn from this study was that the proposed new game physics advances game design and creates value by expanding the choices available to game developers and designers, enabling artists to create more scientifically robust artworks, and encouraging scientists to consider games as a viable tool for education and research. The practical portion generated tangible evidence that the isolated “silos” of engineering, art and science can be bridged when game physics is designed in a transdisciplinary way. This dissertation recommends that scientific and artistic perspectives should always be considered when game physics is used in computer-based media, because significant value for a broad range of practitioners in succinctly different fields can be achieved. The study has thereby established a state of the art research into game physics, which not only offers other researchers constructive principles for future investigations, but also provides much-needed new material to address the observed discrepancies in game theory and digital media design