A general approach to temporal reasoning about action and change

Reasoning about actions and change based on common sense knowledge is one of the most important and difficult tasks in the artificial intelligence research area. A series of such tasks are identified which motivate the consideration and application of reasoning formalisms. There follows a discussion of the broad issues involved in modelling time and constructing a logical language. In general, worlds change over time. To model the dynamic world, the ability to predict what the state of the world will be after the execution of a particular sequence of actions, which take time and to explain how some given state change came about, i.e. the causality are basic requirements of any autonomous rational agent. The research work presented herein addresses some of the fundamental concepts and the relative issues in formal reasoning about actions and change. In this thesis, we employ a new time structure, which helps to deal with the so-called intermingling problem and the dividing instant problem. Also, the issue of how to treat the relationship between a time duration and its relative time entity is examined. In addition, some key terms for representing and reasoning about actions and change, such as states, situations, actions and events are formulated. Furthermore, a new formalism for reasoning about change over time is presented. It allows more flexible temporal causal relationships than do other formalisms for reasoning about causal change, such as the situation calculus and the event calculus. It includes effects that start during, immediately after, or some time after their causes, and which end before, simultaneously with, or after their causes. The presented formalism allows the expression of common-sense causal laws at high level. Also, it is shown how these laws can be used to deduce state change over time at low level. Finally, we show that the approach provided here is expressive

Telling the truth in economic theory

Need a theory's assumptions be true? In a since notorious essay, the economist Friedman argued they need not be and in abstract theories often won't be. The first part of the thesis discusses his case, which has been widely misunderstood,. It concludes that, whilst false assumptions may fulfil the role of epitomising and implying truth, those in Friedman's key economic example do not. The rest of the thesis then relates Friedman's case to that in defence of general equilibrium theory (the heart of orthodox economic theory) and argues that this defence fails. Two complementary arguments against the defenders' position are presented, the first working from the fact that the theory's assumptions are not true and the second considering what would happen if they were - the conclusion being that the theory relates neither to actual cases nor to possible polar ones. Comparisons drawn with rival economic theories end this case-study in the philosophy of economics

Interval Estimation of Functions of Bernoulli Parameters with Reliability and Biomedical Applications

1 online resource (PDF, 108 pages

Dynamic load-balancing of Stream It cluster computations

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 145-147).This thesis discusses the design and implementation of a dynamic load-balancing mechanism for computationally distributed programs running on a cluster written in the StreamIt programming language. StreamIt is useful for streaming data applications such as MPEG codecs. The structure of the language carries a lot of static information, such as data rates and computational hierarchy, and therefore lends itself well to parallelization. This work details a simulator for StreamIt cluster computations used to measure metrics such as throughput. Built on top of this simulation is an agent-based market used for load balancing the computation at StreamIt check-points to adapt to exogenously changing loads on the nodes of the cluster. The market models the structure of the computation as a supply chain. Our experiments study the throughput produced by the market compared to other policies, as well as qualitative features such as stability.by Eric Todd Fellheimer.M.Eng

Anonymous, authentic, and accountable resource management based on the E-cash paradigm

The prevalence of digital information management in an open network has driven the need to maintain balance between anonymity, authenticity and accountability (AAA). Anonymity allows a principal to hide its identity from strangers before trust relationship is established. Authenticity ensures the correct identity is engaged in the transaction even though it is hidden. Accountability uncovers the hidden identity when misbehavior of the principal is detected. The objective of this research is to develop an AAA management framework for secure resource allocations. Most existing resource management schemes are designed to manage one or two of the AAA attributes. How to provide high strength protection to all attributes is an extremely challenging undertaking. Our study shows that the electronic cash (E-cash) paradigm provides some important knowledge bases for this purpose. Based on Chaum-Pederson’s general transferable E-cash model, we propose a timed-zero-knowledge proof (TZKP) protocol, which greatly reduces storage spaces and communication overheads for resource transfers, without compromising anonymity and accountability. Based on Eng-Okamoto’s general divisible E-cash model, we propose a hypercube-based divisibility framework, which provides a sophisticated and flexible way to partition a chunk of resources, with different trade-offs in anonymity protection and computational costs, when it is integrated with different sub-cube allocation schemes. Based on the E-cash based resource management framework, we propose a privacy preserving service oriented architecture (SOA), which allows the service providers and consumers to exchange services without leaking their sensitive data. Simulation results show that the secure resource management framework is highly practical for missioncritical applications in large scale distributed information systems

Theoretical examination and practical implementation on cryptography algorithms, digital money protocols and related applications.

by Shek Wong.Thesis submitted in: December 1997.Thesis (M.Phil.)--Chinese University of Hong Kong, 1998.Includes bibliographical references (leaves 90-[94]).Abstract also in Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Electronic Commerce --- p.3Chapter 1.2 --- Electronic Cash --- p.7Chapter 1.3 --- What This Report Contains --- p.9Chapter 2 --- Cryptographic Background --- p.11Chapter 2.1 --- Euler Totient Function --- p.12Chapter 2.2 --- Fermat's Little Theorem --- p.12Chapter 2.3 --- Quadratic Residues --- p.12Chapter 2.4 --- Legendre Symbol --- p.13Chapter 2.5 --- Jacobi Symbol --- p.14Chapter 2.6 --- Blum Integer --- p.16Chapter 2.7 --- Williams Integer --- p.18Chapter 2.8 --- The Quadratic Residuosity Problem --- p.19Chapter 2.9 --- The Factorization Problem --- p.20Chapter 2.10 --- The Discrete Logarithm Problem --- p.20Chapter 2.11 --- One-way Functions --- p.21Chapter 2.12 --- Blind Signature --- p.22Chapter 2.13 --- Cut-and-choose Methodology --- p.24Chapter 3 --- Anatomy and Panorama of Electronic Cash --- p.26Chapter 3.1 --- Anatomy of Electronic Cash --- p.26Chapter 3.1.1 --- Three Functions and Six Criteria --- p.28Chapter 3.1.2 --- Untraceable --- p.29Chapter 3.1.3 --- Online and Off-line --- p.30Chapter 3.1.4 --- Security --- p.32Chapter 3.1.5 --- Transferability --- p.33Chapter 3.2 --- Panorama of Electronic Cash --- p.34Chapter 3.2.1 --- First Model of Off-line Electronic Cash --- p.34Chapter 3.2.2 --- Successors --- p.35Chapter 3.2.3 --- Binary Tree Based Divisible Electronic Cash --- p.36Chapter 4 --- Spending Limit Enforced Electronic Cash --- p.37Chapter 4.1 --- Introduction to Spending Limit Enforced Electronic Cash --- p.37Chapter 4.2 --- The Scheme --- p.41Chapter 4.3 --- An Example --- p.44Chapter 4.4 --- Techniques --- p.47Chapter 4.5 --- Security and Efficiency --- p.51Chapter 5 --- Interest-bearing Electronic Cash --- p.53Chapter 5.1 --- Introduction to Interest-bearing Electronic Cash --- p.53Chapter 5.2 --- An Example --- p.55Chapter 5.3 --- The Scheme --- p.55Chapter 5.4 --- Security --- p.57Chapter 5.5 --- An Integrated Scheme --- p.58Chapter 5.6 --- Applications --- p.59Chapter 6 --- Abacus Type Electronic Cash --- p.61Chapter 6.1 --- Introduction --- p.61Chapter 6.2 --- Abacus Model --- p.63Chapter 6.3 --- Divisible Abacus Electronic Coins --- p.66Chapter 6.3.1 --- Binary Tree Abacus Approach --- p.66Chapter 6.3.2 --- Multi-tree Approach --- p.57Chapter 6.3.3 --- Analysis --- p.69Chapter 6.4 --- Abacus Electronic Cash System --- p.71Chapter 6.4.1 --- Opening Protocol --- p.71Chapter 6.4.2 --- Withdrawal Protocol --- p.74Chapter 6.4.3 --- Payment and Deposit Protocol --- p.75Chapter 6.5 --- Anonymity and System Efficiency --- p.78Chapter 7 --- Conclusions --- p.80Chapter A --- Internet Payment Systems --- p.82Chapter A.1 --- Bare Web FORM --- p.82Chapter A.2 --- Secure Web FORM Payment System --- p.85Chapter A.3 --- Membership Type Payment System --- p.86Chapter A.4 --- Agent Based Payment System --- p.87Chapter A.5 --- Internet-based POS --- p.87B Papers derived from this thesis --- p.89Bibliography --- p.9

Essays in economic prehistory

This thesis consists of three papers that explore early human organization. In the first paper I argue that the economic and social structure of early humans would have resulted in an especially difficult consanguinity problem. In particular, adverse selection in the exogamous marriage market would have resulted in high levels of consanguinity and resulting fitness depression. A partial solution to this problem was the evolution of aversion to endogamy, known as the Westermarck effect, and was essential for the survival of our species. The second paper (joint with Haiyun Chen) develops a model that explains linguistic diversity as the cumulative result of strategic incentives faced by linguistic groups. In this model, autonomous groups interact periodically in games that represent either cooperation, competition, or a lack of interaction. Common language facilitates cooperation such as trade, whereas language unique to one group affords that group an advantage in competitive interactions. The relative frequency of cooperation and conflict in a region provides incentives for each group to modify their own language, and therefore leads to changes in linguistic diversity over time. Our model predicts that higher frequency of conflict relative to cooperation will increase a region\u27s linguistic diversity. The third paper (joint with Gregory K. Dow and Clyde G. Reed) investigates the incidence of early warfare among foragers and farmers in prehistory. Our focus is specifically on conflict over land. Food is produced using inputs of labor and land, and the probability of victory in a conflict depends on relative group sizes. The group sizes are determined by individual migration and Malthusian population dynamics. Both factors result in larger populations at better sites, which deters attack. There are two necessary conditions for warfare: high enough individual mobility costs and large enough shocks to the relative productivities of the sites. Together, these conditions are sufficient. In particular, technological or environmental shocks that alter the productivities of sites can trigger warfare, but only if individual agents do not change sites in response. These results are consistent with evidence from archaeology and anthropology

Statistical estimation and prediction in probabilistic models with application to structural reliability.

Massachusetts Institute of Technology. Dept. of Civil Engineering. Thesis. 1974. Ph.D.MICROFICHE COPY ALSO AVAILABLE IN BARKER ENGINEERING LIBRARY.Vita.Includes bibliographies.Ph.D