A zero-knowledge proof system of knowledge is a protocol between two parties called the prover and the verifier. The prover wants to convince the verifier that he “knows” the proof of a given theorem without revealing any additional information. This is different from a zero-knowledge proof system of membership where the prover convinces the verifier only of the veridicity of the statement. Zero-knowledge proofs of knowledge are very useful tools in the design of secure protocols. Though, the concept of a proof of knowledge is a very subtle one and great care is needed to obtain a satisfying formalization. In this paper, we investigate the concept of a zero-knowledge proof of knowledge in the noninteractive model of [5, 61. Here, the prover and the verifier share a short random string and the only communication allowed is from the prover to the verifier. Although this is a simpler model than the interactive one, still formalizing zeroknowledge proofs of knowledge is a delicate task. The main results of the paper are the following e We present formal definitions for the concept of non-interactive zero-knowledge proofs
A zero-knowledge proof system of knowledge is a protocol between two parties called the prover and the verifier. The prover wants to convince the verifier that he 'knows' the proof of a given theorem without revealing any additional information. This is different from a zero-knowledge proof system of membership where the prover convinces the verifier only of the veridicity of the statement. Zero-knowledge proofs of knowledge are very useful tools in the design of secure protocols. Though, the concept of a proof of knowledge is a very subtle one and great care is needed to obtain a satisfying formalization. The authors investigate the concept of a zero-knowledge proof of knowledge with a non-interactive model. Here, the prover and the verifier share a short random string and the only communication allowed is from the prover to the verifier. Although this is a simpler model than the interactive one, still formalizing zero-knowledge proofs of knowledge is a delicate task.>
In this note, we present new zero-knowledge interactive proofs and arguments for languages in NP. To show that x ε L, with an error probability of at most 2-k, our zero-knowledge proof system requires O(|x|c1)+O(lgc2|x|)k ideal bit commitments, where c1 and c2 depend only on L. This construction is the first in the ideal bit commitment model that achieves large values of k more efficiently than by running k independent iterations of the base interactive proof system. Under suitable complexity assumptions, we exhibit zero knowledge arguments that require O(lgc|x|kl bits of communication, where c depends only on L, and l is the security parameter for the prover. This is the first construction in which the total amount of communication can be less than that needed to transmit the NP witness. Our protocols are based on efficiently checkable proofs for NP[4].
Introduction - new perspectives on the Cultural Revolution, William A. Joseph et al. Part 1 Politics: learning from trauma - the Cultural Revolution in post-Mao politics, Lowell Dittmer Cultural Revolution radicalism - variations on a Stalinist theme, Andrew G. Walder agrarian radicalism as a rural development strategy, 1968-1978, David Zweig the Cultural Revolution as an unintended result of administrative policies, Lynn T. White, III factional politics in Zhejiang, 1973-1976, Keith Forster. Part 2 Economics: neither plan nor market - Mao's political economy, Carl Riskin industrial policy during the Cultural Revolution - military preparation, decentralization, and leaps forward, Barry Naughton the Maoist reconsidered - local self-reliance and the financing of rural industrialization, Christine P. W. Wong central-provincial investment and finance - the Cultural Revolution and its legacy in Jiangsu Province, Penelope B. Prime. Part 3 Culture: arts policies of the Cultural Revolution - the rise and fall of Culture Minister Yu Huiyong, Richard Kraus models and misfits - rusticated youth in three novels of the 1970s, Richard King dramas of passion - heroism in the Cultural Revolution's model operas, Ellen R. Judd.
This document reports the findings of an examination of a variety of state government efforts to assist local government in obtaining infrastructure, particularly water supply, wastewater treatment, and solid waste disposal facilities. The project team sought examples of innovative practices that could serve as models for other state and local agencies. The scope of this effort did not permit the team to evaluate in-depth these state programs. The information is presented under nine topics, which are also chapter heading for chapters 2 through 10: (2) terms and conditions, and special requirements; (3) scope of financial assistance programs; (4) project selection process; (5) providing technical assistance; (6) decentralized decision-making; (7) bond banks; (8) monitoring and evaluation; (9) assessing statewide future needs; and (10) privatization. The first chapter is an introduction to the report and the final chapter (11) contains recommendations to the Federal government.
Manuel Blum, Alfredo De Santis, Silvio Micali, Giuseppe Persiano
This paper investigates the possibility of disposing of interaction between prover and verifier in a zero-knowledge proof if they share beforehand a short random string. Without any assumption, it is proven that noninteractive zero-knowledge proofs exist for some number-theoretic languages for which no efficient algorithm is known. If deciding quadratic residuosity (modulo composite integers whose factorization is not known) is computationally hard, it is shown that the NP-complete language of satisfiability also possesses noninteractive zero-knowledge proofs.
Finding the proper balance between central control and local autonomy is a perennial problem in the Chinese economy, and the Chinese fiscal system has undergone numerous changes in central-provincial revenue-sharing arrangements since the 1950s. In the post-Mao period, fiscal decentralization began in 1980 under the slogan of “cooking in separate kitchens” ( fenzao chifan ), and a series of reforms was implemented to put local governments increasingly on a self-financing basis. However, this attempt to revamp the financial interaction between the central and provincial governments has been made immensely more complicated by rapid changes in the fiscal system and the shifting composition of revenues and expenditures brought by economic reform.
After providing… [public expenditure] … theory with its… optimal conditions, I went on to demonstrate the fatal inability of any decentralized market or voting mechanism to attain or compute this optimum [Samuelson, (1955), p. 35]. … to say that market mechanisms are non-optimal, and that there are difficulties with most political decision processes, does not imply that we can never find new mechanisms of a better sort [Samuelson (1958), p. 334]. Providing the [public] expenditure in question holds out any prospect at all of creating utility exceeding costs, it will always be theoretically possible, and approximately so in practice, to find a distribution of costs such that all parties regard the expenditure as beneficial and may therefore approve it unanimously [Wicksell (1896), pp. 89-90]. How much of this [the principle of unanimity and voluntary consent in taxation] … may be of practical use in the near future, men of affairs may decide [Wicksell (1896), p. 73]. INTRODUCTION The theory of public goods has, in the space of 20 years, revolutionized teaching and research in public finance, had a major impact on the content of microeconomic theory in general, and has provided, for many, the analytical foundation for an economic justification for the state. The most widely accepted proposition in contemporary public finance is the “fatal inability” of decentralized market or voting institutions to attain a Pareto-optimal allocation of resources when there are public goods.
Carolyn Johnson, Theresa A. Nicklas, Marian L. Arbeit, D W Harsha · 8 authors
The Heart Smart Family Health Promotion Program is a multidisciplinary, school-based program for cardiovascular risk reduction among high-risk children and their families. As a program that includes young adults at high risk, it is adaptable to a clinical practice. Nineteen fourth and fifth graders were selected as probands for elevated risk factors after a general screening to identify families for an intervention program. Twenty-three parents participated in a 12-week program focused on eating, exercise, and smoking behavior changes enhanced by behavicral support strategies. Weekly sessions were held in the auditorium/cafeteria of the elementary school and consisted of orientation and presentations, cardiovascular (CV) screening with medical feedback, activities, self-monitoring, counseling, and contingency contracting. Information gathered before and after the program included medical history, CV health knowledge and relevant behavior, blood pressure, serum lipid and lipoprotein values, anthropometric measurements, and urine electrolyte excretion. Both children and parents showed positive changes in eating habits and physical activity and significant changes in knowledge and blood pressure levels, while the children halted their weight gain. We believe this multidisciplinary, behavior-oriented, school-based program can be an effective cardiovascular risk intervention adaptable for a clinical office practice.
Local government Gordon Hughes and Stephen Smith Many OECD countries are uncomfortable with the structure and financing of their decentralized governments. In some, the pressures for change have even led to tax revolts. Much of the existing economic literature on decentralization considers that the purpose of local governments is to decentralize decisions. Lower tiers of government are assigned local public goods and matching taxes. This contrasts with actual arrangements. The patterns of government decentralization in OECD countries are diverse. Most local governments in Europe actually perform a major administrative role, in effect acting as agents for the central government. While this is justified by the advantages that local governments have over central governments in terms of information and control by voters, such arrangements require large financial resources, and more control by central government than where local governments simply provide local public goods. A drawback is the potential for conflict between different tiers of government. The trend towards more decentralization, common to most countries, has had to be met by more taxation or more grants. The need for revenue has encouraged a move away from property taxes to broader-based local taxes. Tax-sharing arrangements have often been under-rated, but in practice they compare favourably with complex and discretionary systems of transfers between levels of government.
Control system design is considered for attitude control and vibration suppression of flexible space structures. The problem addressed is that of controlling both the zero-frequency rigid-body modes and the elastic modes. Model-based compensators, which employ observers tuned to the plant parameters, are first investigated. Such compensators are shown to generally exhibit high sensitivity to the knowledge of the parameters, especially the elastic mode frequencies. To overcome this problem a class of dynamic dissipative compensators is next proposed, which robustly stabilize the plant in the presence of unmodeled dynamics and parametric uncertainties. An analytical proof of robust stability is given, and a method of implementing the controller as a strictly proper compensator is given. Methods of designing such controllers to obtain optimal performance and robust stability are presented. Numerical and experimental results of application of the methods are presented, which indicate that dynamic dissipative controllers can simultaneously provide excellent performance and robustness.
To contain the escalating cost of health care, a prospective payment system is being introduced into the military. The authors propose a proactive approach to this change in health care financing by evaluating the experiences of nurses to a similar change in the civilian sector. These approaches are presented as nine interrelated lessons: responding optimistically; shifting into a business mode; valuing clinical nursing experts; understanding the implications for documentation; moving to decentralized management; changing outpatient care delivery; considering the effects on job satisfaction; evaluating the relationship between costs and nursing resource consumption; and basing nursing practice in science.
James D. Bentley, J Chusid, G D'Antuono, Joyce V. Kelly · 5 authors
The contemporary academic medical center is a complex organization providing medical and other professional health education, biomedical and behavioral research, and a comprehensive range of patient care services. This paper presents data from the Association of American Medical Colleges' 1989 survey of 125 member faculty practice plans. The survey data showed that 62% of the 74 responding plans were units or associations within the medical school corporate structure. Plans were organized along a broad continuum from the autonomous, departmental model with decentralized governance and management to the group model with centralized governance and management. The growth of managed care, increased competition, and a greater reliance by the medical school on clinical practice income as a financing source are causing the practice plan to expand beyond billing of professional fees. The survey data showed that 75% of the practice plans operated satellite centers, and 61% planned to build new ambulatory care facilities in order to expand and improve services to patients. The practice plans also have adapted to changes in third-party reimbursement and are establishing mechanisms to negotiate managed care contracts involving multiple clinical departments to increase referrals and maintain patient shares; 86% of the plans participate in at least one managed-care organization. The role of the practice plan will continue to evolve in response to the needs of the academic medical center for a cooperative and supportive environment in which to conduct its traditional missions of teaching, research, and patient care.
A conceptual framework and a blueprint of the health-financing reform have been proposed to the Soviet Parliament by a group of economists and health policy analysts. The draft law offers a new pattern of health financing that is expected to increase both the volume and quality of medical care through raising additional funds, decentralizing health policies and management, providing medical facilities with higher motivation for productive and cost-effective performance, and creating economic incentives for employees and individuals for better labor conditions, pollution abatement, and healthy lifestyles.
In this paper the generality and wide applicability of Zero-knowledge proofs, a notion introduced by Goldwasser, Micali, and Rackoff is demonstrated. These are probabilistic and interactive proofs that, for the members of a language, efficiently demonstrate membership in the language without conveying any additional knowledge. All previously known zero-knowledge proofs were only for number-theoretic languages in NP fl CONP. Under the assumption that secure encryption functions exist or by using "physical means for hiding information," it is shown that all languages in NP have zero-knowledge proofs. Loosely speaking, it is possible to demonstrate that a CNF formula is satisfiable without revealing any other property of the formula, in particular, without yielding neither a
Increasingly, a volatile public policy issue in rapidly growing areas is traffic congestion. The sprawl of suburban growth, decentralization of urban centers and the shift of jobs from urban centers to suburban areas contributes to traffic congestion. Traditionally, government's response to traffic congestion has been to use engineering, public finance and regulatory control to design and build new highway systems or expand exiting ones. The authors suggest instead that state and local governments use a combination of techniques to better manage land use applications and explore public finance alternatives to achieve a better balance between travel demand, transportation capacity and environmental concerns.
This monograph examines the adequacy of the joint task force (JTF) to operate effectively in the context of wartime uncertainty. Military theorists have long understood the deleterious effects of uncertainty on the conduct of war. Commanders never know as much about the enemy or environmental conditions as they would like, so they decide and act on the best information available, however incomplete. In coping with uncertainty, there are proven methods of structuring one's organization to meliorate its effects. These methods involve decentralizing command, lowering decision thresholds, and creating self-contained, semi-autonomous units. U.S. military doctrine recognizes the need for JTFs in responding to the global commitments of the nation. Unfortunately, Service incompatibilities and parochialism often have hampered the joint commander's ability to get the job done. Congress mandated reform through the Goldwater-Nichols Department of Defense Reorganization Act of 1986; the result has been to streamline joint command structures, thus making them better able to deal with uncertainty. The experience of multi-Service operations during World War II confirms the wisdom of creating joint task forces when doctrinal conditions are met. My research into two of these operations -- FLINTLOCK in the Marshall Islands and HUSKY in Sicily – indicate that an integrated joint command structure, akin to a modern JTF, reduces the effects of uncertainty by allowing the central headquarters to operate with less information.
The authors study an economy where externalities provide an explicit role for intervention and technology shocks generate aggregate uncertainty. In laissez-faire there is too much unemployment. However, the authors show how to support the optimal allocation as a decentralized equilibrium using a self-financing linear employment subsidy. Generally, this subsidy is a function of economic conditions, and they characterize the way in which it varies with the shock. A special case of the authors' results indicates that a simple restriction on technology, homotheticity, implies the optimal subsidy is constant or independent of unemployment. Copyright 1991 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.