Zero knowledge protocols provide a way of proving that a statement is true without revealing anything other than the correctness of the claim. Zero knowledge protocols have practical applications in cryptography and are used in many applications. While some applications only exist on a specification level, a direction of research has produced real-world applications. Zero knowledge protocols, also referred to as zero knowledge proofs, are a type of protocol in which one party, called the prover, tries to convince the other party, called the verifier, that a given statement is true. Sometimes the statement is that the prover possesses a particular piece of information. This is a special case of zero knowledge protocol called a zero-knowledge proof of knowledge. Formally, a zero-knowledge proof is a type of interactive proof.
The notion of a zero knowledge interactive proof that one party "knows" some secret information is explored. It is shown that any "random self-reducible" problem has a zero knowledge interactive proof of this sort. The zero knowledge interactive proofs for graph isomorphism, quadratic residuosity, and "knowledge" of discrete logarithms all follow as special cases. Based on these results, new zero knowledge interactive proofs are exhibited for "knowledge" of the factorization of an integer, nonmembership in cyclic subgroups of Zp*, and determining whether an element generates Zp*. None of these proofs relies on any unproven assumptions.
In this paper we investigate some properties of zero-knowledge proofs, a notion introduced by Goldwasser, Micali and Rackoff. We introduce and classify various definitions of zero-knowledge. Two definitions which are of special interest are auxiliary-input zero-knowledge and blackbox-simulation zero-knowledge. We explain why auxiliary-input zero-knowledge is a definition more suitable for cryptographic applications than the original [GMR1] definition. In particular, we show that any protocol composed of subprotocols which are auxiliary-input zero-knowledge is itself auxiliary-input zero-knowledge. We show that blackbox simulation zero-knowledge implies auxiliary-input zeroknowledge (which in turn implies the [GMR1] definition). We argue that all known zero-knowledge proofs are in fact blackbox-simulation zero-knowledge (i.e. were proved zero-knowledge using blackbox-simulation of the verifier). As a result, all known zero-knowledge proof systems are shown to be auxiliary-input zero-knowledge and can be used for cryptographic applications such as those in [GMW2]. We demonstrate the triviality of certain classes of zero-knowledge proof systems, in the sense that only languages in BPP have zero-knowledge proofs of these classes. In particular, we show that any language having a Las vegas zeroknowledge proof system necessarily belongs to R. We show that randomness of both the verifier and the prover, and nontriviality of the interaction are essential properties of non-trivial auxiliary-input zero-knowledge proofs. In order to derive most of the results in the paper we make use of the full power of the definition of zero-knowledge: specifically, the requirement that there exist a simulator for any verifier, including "cheating verifiers".
ABSTRACT For a nation composed of independent regions, the effects of local tax competition for business investments are examined. It is first shown that atomistic regional authorities tax only local resources to finance the provision of public services to business. Thus, an efficient interregional equilibrium is induced. Various political/institutional constraints are shown to cause misallocation of the capital stock and an inefficient provision of public services. The characterization of the inefficiency is shown to vary widely, depending upon the constraint under consideration.
Abstract Decentralization efforts in Francophone African countries are both rarer and far less ambitious than those in Anglophone states. The decentralization programme launched by Senegal over a decade ago is an important exception. Since 1972, when the administrative reform law took effect, Senegal has been engaged in an effort to decentralize its administrative structures in order to promote rural development, to escape from the burdens of the remnants of an overly centralized colonial system and to stem the rising tide of rural opposition (malaise paysan). This new initiative, which led to the creation of local elected councils in rural communities (communautés rurales). has thus far achieved only marginal success. The 319 rural councils suffer from serious under‐financing, and often from domination by administrative authorities, especially the sous‐préféts. Based on an examination of the attitudes. perceptions and behaviour of a sample of rural councillors ( n = 144), particularly regarding budgetary matters, it appears that the rural communities in fact provide the possibility for some popular input into local and regional planning.
ABSTRACT Type/Token Ratios have been extensively used in child language research as an index of lexical diversity. This paper shows that the measure has frequently failed to discriminate between children at widely different stages of language development, and that the ratio may in fact fall as children get older. It is suggested here that such effects are caused by a negative, though non-linear, relationship between sample size (i.e. number of tokens) and Type/Token Ratio. Effects of open and closed class items are considered and an alternative Verbal Diversity measure is examined. Standardization of the number of tokens before computing Type/Token Ratios is recommended.
Emmanuel Jiménez, George Psacharopoulos, Jee-Peng Tan
With the current constrained financial conditions in many developing countries, it is essential to develop and utilize new methods of financing education to ensure efficiency and greater social equity. The current financing arrangements in many cases result in an underinvestment in education, an untapped willingness to pay for education and a misallocation of public spending in this sector. This report examines three broad policy options that could remedy the above problems. It is argued that they would result in an increase of resources flowing to education, improve their use, and ensure more equitable access to schooling. Although the suggested reforms need to be phased in gradually, and their specific content will differ among countries, the package includes three elements. They comprise: (1) recovering the public cost of higher education and reallocating government spending on education toward the level with the highest social returns; (2) developing a credit market for education, together with selective scholarships, especially in higher education; and (3) decentralizing the management of public education and encouraging the expansion of private and community-supported schools.
Gail Henderson, Yuanli Liu, Xiaoming Guan, Zongxiu Liu
Chinese hospitals in the 1980s are in the midst of a technological revolution. Based upon data from several regions in China, this paper describes the political, organizational, economic, and philosophical changes which have accompanied the shift in focus from primary care medicine to high technology tertiary care. The increased authority of physicians, greater contact with the West, and increased funding for medical equipment are key factors in these changes. Although the Chinese state continues to control the administration and financing of most hospitals, the decentralizing reforms of Deng Xiaoping have undermined its ability to effectively plan for, and assess new technology. At present, limited resources prevent most regions from excessive technology acquisition, but the state must rebuild its planning capacity in order to foster rational allocation of scarce medical resources.
This paper examines the relation between computer networking by On-line System and the role of branch offices in Fukuoka CBD. There are two impacts of computer networking on multi-locational firms. These impacts are related with the locational trends of head and branch offices. One is changes in the role or the position of a branch office, and the other is the influence of an On-line System as a communication medium on meetings and telephone contacts. The characteristics and trends of computer networking and business tasks managed through an On-line System are discussed. As well, the influence of the introduction of an On-line System on the frequencies of meetings and telephone contacts are also discussed. The results are as follows : 1) Network-type of an On-line System ; This is classified into six types : three types with a decentralized pattern of computer networking and the other three types with a centralized pattern. Centralized types which have a host-computer set up in a head office, are unevenly distributed in finance and insurance sectors, while decentralized types which have sub-computers set up in branch offices are unevenly distributed in wholesale and other sectors. In finance and insurance, there are two trends ; expansion of a centralized network pattern, and a shift to a decentralized type. On the other hand, decentralized types are increasing in wholesale and other sectors. 2) Characteristics of business tasks ; a) Offices with a decentralized pattern perform a greater number of business tasks through an On-line System than ones with a centralized pattern. b) As well, these offices perform a greater number of market planning and management tasks than ones with a centralized pattern. The shift to a decentralized pattern makes such trends concerning business tasks possible. c) Finance and insurance sectors generally declare that business authority within branch offices have remained unchanged. Though the major trend is to maintain this status quo, there is also a lesser trend which gives added authority to branch offices. In wholesale and other sectors, the trend is clear that the role of branch offices are being strengthened. 3) Introduction of an On-line System causes a decrease in the frequency of telephone calls in communication within the same firm. But there is little influence of its introduction on the frequencies of meetings and telephone calls in communicating with other firms. Therefore, an On-line System as a communication medium does not lessen the value of face-to-face meetings in communications between firms.
1. A. Weil [3] constructed a universal distribution t on the Weil group.The values of I at various test functions give the contributions from the zeros of L-functions which appear in the .explicitformulas.In this note, we shall construct a universal distribution zi on GL(n) and prove the explicit formula for automorphic L-functions using z/ when n-2.For n 2, to derive such a result, we must assume certain property of characters of infinite dimensional representations of GL(n) over a local field.This property, formulated as Conjecture, seems to lie slightly beyond our present knowledge of harmonic analysis.The distributions A have striking formal resemblance to Weil's one.Furthermore they are related to each other so that zl is the "direct image" of z/ for m n.This is a pleasant fact since we think that a discovery of new functorial properties related to zeros of zeta functions would be crucial for the proof of the Riemann hypothesis.
In a decentralized fiscal system, it has been suggested that socio-economic characteristics have a more profound impact upon the fiscal system than do the political variables. However, in a centralized fiscal system, local government finance is constrained not only by limited local autonomy by the central government but also must respond to local demand influences on fiscal behavior. It is of interest to assess the responsiveness of the local government fiscal behavior to local socio-economic characteristics. The variation in the municipal fiscal system are analyzed using data from municipalities in Thailand during 1979-1982 as a case study. The reason for using municipalities as the case study is because of their relatively greater degree of autonomy over their fiscal systems. This study divided the municipalities into three types, namely, Nakorn, Muang, and Tambon, according to the central government classification. The purpose of this study is to explore the relationship between municipal fiscal systems and differences in local socio-economic conditions. The municipal fiscal study here includes both revenue and expenditures. On the revenue side, the study analyzes the variation of municipal revenue from both tax and non-tax revenues. On the other hand, the municipal expenditure included in this study are services required by the central government, i.e., primary education, public administration, public works, public health services, public safety, sanitation, central and specific funds. The variation of each revenue and expenditure is studied in terms of its relationship to income, relative size of the municipal population, and population density. Because of data limitations neither a behavioral function nor a budget constraint could be specified to obtain a formal demand equation. Therefore, the results of the statistical estimation of the model employed can only be interpreted as a measure of the systematic variations in municipal fiscal systems, not the determinants of the levels of these revenues and expenditures. The results show that while there exist differences in the level of revenue and expenditure in each type of municipality, the socio-economic variables are generally not significant in explaining the variation of revenues and expenditures. The political factors have a considerably larger effect on the variation of municipal fiscal systems. One of these factors is the previous year revenue and expenditure level.
In order to frame the financial problem of the agricultural sector in greece, this sector, in the firt part of the thesis, is replaced, firstly in its general economic context and then in the general framework of the financial system in greece ; a special emphasis is put on the role of the agricultural bank of greece. The second part of the work is devoted to the analysis of the main sources abroad, and the main procedures of short and long term credits used mainly by the bank. Because of its structural weaknesses, greek agriculture is unable to use efficiently the available financial ressources which remain insufficient. The case is discussed of an evolution of the status of the bank, a statual institution, towards a national cooperative scheme, gathering more ressources from its deposits and aiming at a more decentralized and professional way of financing while maintaining a lower cost of financing for the agricultural sector, as it is observed in some other countries of the eec.
Pluralism and elitism are the two prevailing theories of policy making in the United States. The purposes of this article are to suggest an alternative framework linkage political economy and to evaluate that framework against both pluralist and elitist policy explanations. The evaluation will take place within the medium of a case study on housing policy. The linkage political economy framework addresses some of the weaknesses evident in both pluralist and elitist studies of public policy. For example, in the housing policy field, elite theorists assert that policy making is dominated by a cohesive, politically powerful corporate bloc made up of the construction, finance, and realty industries.I But the elite theorists are then hard pressed to explain policy failures of this dominant coalition such as the passage of the 1937 public housing program or the original low-income thrust of the 1949 urban redevelopment program. On the other hand, pluralist analysts find a much more open and balanced policy process with a wide spectrum of interests able to be heard through multiple channels available in a decentralized political process.2 Yet, this pluralist analysis cannot adequately explain the consistent bias in U.S. housing policies and out-
This paper is concerned wth the classic "guns versus butter" dlemma.There are two countries engaged in an arms race.The first country is a decentralized market economy and the second country is a command economy.This asymmetry might capture the difference between West and East.The government of each country maximizea the life-time utility of the representative consumer, which depends upon conaumption, leisure and defence.Defence is a characteriatic, which depends positively upon the own weapon stock and negatively upon the foreign weapon stock.The government of the first country usea distortionary taxes on labour ncome to finance the provision of public goods, whereas the government of the second country simply commands its constituents.This paper contrasts coordinated and decentralized decision making.It is argued that coordinated policiea lead to lower levels of government spending and arms accumulation.As far as decentralized decision making is concerned, it is crucial to distinguish between openloop, general closed-loop and subgame-perfect Nash equilibria.The openloop Nash equilibrium relies upon pre-commitment to an announced path of ~This paper was presented to a Meeting of the European Public Choice Society, April 2-5, 1986, Noordwjkerhout, The Netherlands and to a Conference on International Economic Security organized by the Centre for Economic Policy Research, June 19R6, London.The authors are grateful to the participants of those meetings for their comments and to A. Markink for excellent computational assistance.government spending and is the solution concept moet frequently used in the literature.The problem with this concept is that it relies upon very restrictive i nformation sets and over-eatimates the inefficiencea generated by the arms race.The closed-loop Nash equilibrium allows each country to have knowledge of current and past weapon stocks.Within this framework it is possible to model threata, which can induce cooperative behaviour.The principle of subgame-perfection gves uniquenesa and credibility within the class of closed-loop Nash equilibria.This subgameperfect equilibrium coincides with the open-loop equilibrium when utility is separable in home and foreign weapon stocks.In general, this is not the case and subgame-perfect equilibria typically lead to less arms accwnulation than open-loop equilibria.This i llustrates that i n a gametheoretic context an increase in information can make both countries better off and countries should therefore be encouraged to monitor the weapon stocka of their rival.The results are illustrated wth a numerical example based upon CES utility functions and linear technologiea.This gives an opportunity to test a recently developed algorithm for the calculation of aubgameperfect equilibria i n dynamic gamea.