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Mira Belenkiy, Jan Camenisch, Melissa Chase, Markulf Kohlweiss · 6 authors
No abstract is available for this record.
Eddo Rigotti, Sara Greco
No abstract is available for this record.
Paulos Chanie
Post-1991 Decentralization reform in Ethiopia reveals that regional governments have technically separate power to self administer their regions, formulate and implement their socio-economic policies and strategies, bear all financial expenditures, raise revenue from specified tax bases, get subsidies from the central government and borrow from internal sources. The implementation of the reform, however, shows sustained central government dominance on expenditure and revenue assignment, continued regional dependence on central subsidy, absence of borrowing, and sustained central government interference in the administrative affair of regions. By conducting detailed field research in three regional governments, this article exposes how public sector management system (public finance and human resource management system) determines decentralization outcomes. It contends that outcomes of decentralization reforms are shaped not only by political and economic factors, as suggested in the decentralization literature, but also by the de facto public sector management system.
Lasheng Yuan
The objective of the three essays of this doctoral dissertation is to investigate the strategic choices of organizational forms by competing firms in various environments. The first essay, which is a joint work with Professor Guofu Tan, provides an alternative theory of divestitures that relies on product-line complementarities and product market competition. We consider a simple environment in which there axe two firms, each supplying a group of complementary products and the products across groups axe imperfect substitutes. We model the firms' choices of divesting and pricing as a two-stage game. The duopohsts simultaneously choose their divestiture strategies in the first stage of the game and the independent divisions compete by setting prices in the second. It is shown that, when competing with each other, firms with complementary product-lines have incentives to split into multiple independent divisions supplying complementary products and services. Such divestitures increase prices and the parent firms' values but reduce aggregate social welfare. Moreover, the degree of divestiture, as we illustrate in the linear demand case, depends on the severity of competition and the nature of product-lines. Then, intensified competition due to deregulation, trade liberalization and entry may trigger divestitures. We further show that if two firms axe able to coordinate their divestiture strategies, they can achieve the joint monopoly prices and profits in a non-cooperative price game. The second essay analyzes the strategic incentive of oligopolists to create autonomous rival divisions when products are differentiated. We consider a two stage game where firms choose the number of autonomous divisions in the first stage and all the divisions engage in Cournot competition in the second. It is shown that product differentiation ensures the existence of an interior subgame perfect Nash equiubrium, and the equilibrium number of divisions increases with the degree of substitution among products and the number of firms. Further, if divisions are allowed to further divide, they always will, which leads to total rent dissipation. Thus, parent firms have incentives to unilaterally restrict their divisions from further dividing. In the free entry equihbrium, it is found that the possibility of setting up autonomous divisions is a natural barrier to entry. Incumbents may persistently earn abnormally high profits. In the cases where product differentiation is difficult, the only pure strategy free entry equilibrium is the monopoly outcome even if the entry cost is relatively low. The third essay develops a game theoretic model to analyze strategic leasing behaviors of landowners in a nonexclusively owned common oil pool. The oil field development is modeled as two more-or-less independent one-stage noncooperative game. The landowners choose leasing strategies in the first stage, and independent lease operators choose extraction strategies in the second. It is found that, in a nonexclusively owned oil field, it is individually rational for a landowner to unilaterally subdivide his landholding and delegate production rights to multiple independent firms, even though more dispersed production control leads to heavier common pool losses. Moreover, the degree of landownership concentration determines the degree of production concentration. The more fragmented the land ownership, the lower is the degree of production concentration i n equilibrium. The analysis offers an explanation for the puzzling landowners' leasing behaviors in U . S . onshore oil fields.
Michael Backes, Cătălin Hriţcu, Matteo Maffei, Thorsten Tarrach
We present the first static analysis technique for verifying implementations of cryptographic protocols based on zero-knowledge proofs. Protocols are implemented in RCF∧∨, a core calculus of ML with support for concurrency. Cryptographic primitives are considered as fully reliable building blocks and represented symbolically using a sealing mechanism. Zero-knowledge proofs, in particular, are specified in a high-level language and automatically compiled down to a symbolic implementation using seals. Security properties are formalized as authorization policies and statically enforced by a type system featuring refinement, union, intersection, and polymorphic types. The expressiveness of our type system allows us to analyze not only protocols based on zero-knowledge proofs but also other important protocol classes that were out of the scope of existing static analysis techniques.
Chengming Qi
In this paper, we proposed a new signature scheme based on elliptic curve cryptography. We combined the two problems, factoring and logarithm problem into both signing and verifying equations. We also give a kind of algorithm of the zero-knowledge proof of proposed digital signature. The new scheme was shown to be secure against the known attacks for signature schemes. This algorithm has characteristics which has little computation, high reliability, and easy to be realized.
Liv Bjornestad
This paper provides an in-depth analysis of the relationship between fiscal decentralization and pro-poor outcomes based on the role of fiscal incentives. The literature on the relationship between fiscal decentralization and pro-poor outcomes is not well established in this area. A conceptual model is developed to explore in more detail this relationship, while endeavoring to illuminate the complexity of the issues involved for policy makers in developing countries. Four types of fiscal incentives are explored: namely, resources, responsibility, autonomy, and accountability. The paper then assesses the effectiveness of the Vietnamese system of fiscal decentralization for achieving pro-poor outcomes through a devolved system of fiscal incentives. The paper suggests that evidence from the Vietnamese case indicates that fiscal decentralization may contribute to poverty reduction outcomes, but does not provide evidence that fiscal decentralization is in and of itself inherently pro-poor. Rather, the lesson from Viet Nam is that if poverty reduction is an explicit objective for government, the system of fiscal decentralization should target pro-poor outcomes through an appropriate system of fiscal incentives. Since 2002, budgetary reallocation and income redistribution linked to poverty outcomes has been more strongly associated with equalizing fiscal transfers than with devolved finances in general. This represents a broadly correct approach to target poverty outcomes in a territorially unbalanced country like Viet Nam. Targeted transfers contribute to pro-poor outcomes by increasing the level of resources available to finance poverty spending. However, increasing the level of fiscal transfers for poverty spending will not ensure that fiscal transfers are then spent efficiently. In order to better realize these efficiency objectives, the government can promote greater fiscal and administrative decentralization of resources and responsibility to district- and commune-level governments. Further gains in this area must also be supported by greater levels of fiscal autonomy and fiscal accountability at the local government level.
Aggelos Kiayias, Hong-Sheng Zhou
No abstract is available for this record.
Wang Yu-wu, You-Bang Zhan, (1)淮阴师范学院计算机科学系,淮安 223300; (2)淮阴师范学院物理系,淮安 223300
A theoretical scheme for zero-knowledge proof quantum identity authentication is proposed by the absolutely impartial third party CA， which has been realized based on remote state preparation and assisted cloning controlled means. In the process of identification， only CA knows the information of quantum identity card and the first party Alice and the second party Bob can accomplish the quantum identity authentication without knowing it. We discuss the probability of accomplishing this job. The security of this scheme is unconditional and it is guaranteed by quantum mechanism.
Essam Ghadafi, Nigel P. Smart, Bogdan Warinschi
No abstract is available for this record.
Yehuda Lindell, Hila Zarosim
Abstract. In the setting of secure computation, a set of parties wish to securely compute some function of their inputs, in the presence of an adversary. The adversary in question may be static (meaning that it con-trols a predetermined subset of the parties) or adaptive (meaning that it can choose to corrupt parties during the protocol execution and based on what it sees). In this paper, we study two fundamental questions relating to the basic zero-knowledge and oblivious transfer protocol problems: – Adaptive zero-knowledge proofs: We ask whether it is possible to con-struct adaptive zero-knowledge proofs (with unconditional sound-ness). Beaver (STOC 1996) showed that known zero-knowledge proofs are not adaptively secure, and in addition showed how to construct zero-knowledge arguments (with computational soundness). – Adaptively secure oblivious transfer: All known protocols for adap-tively secure oblivious transfer rely on seemingly stronger hardness assumptions than for the case of static adversaries. We ask whether this is inherent, and in particular, whether it is possible to construct adaptively secure oblivious transfer from enhanced trapdoor permu-tations alone. We provide surprising answers to the above questions, showing that achieving adaptive security is sometimes harder than achieving static se-curity, and sometimes not. First, we show that assuming the existence of one-way functions only, there exist adaptive zero-knowledge proofs for all languages in NP. In order to prove this, we overcome the problem that all adaptive zero-knowledge protocols known until now used equivocal commitments (which would enable an all-powerful prover to cheat). Sec-ond, we prove a black-box separation between adaptively secure oblivious transfer and enhanced trapdoor permutations. As a corollary, we derive a black-box separation between adaptively and statically securely obliv-ious transfer. This is the first black-box separation to relate to adaptive security and thus the first evidence that it is indeed harder to achieve security in the presence of adaptive adversaries than in the presence of static adversaries. 1
Rikke Bendlin, Ivan Damgård
Abstract. We present a variant of Regev’s cryptosystem first presented in [Reg05], but with a new choice of parameters. By a recent classical re-duction by Peikert we prove the scheme semantically secure based on the worst-case lattice problem GapSVP. From this we construct a threshold cryptosystem which has a very efficient and non-interactive decryption protocol. We prove the threshold cryptosystem secure against passive adversaries corrupting all but one of the players, and againts active ad-versaries corrupting less than one third of the players. We also describe how one can build a distributed key generation protocol. In the final part of the paper we show how one can, in zero-knowledge- prove knowledge of the plaintext contained in a given ciphertext from Regev’s original cryptosystem or our variant. The proof is of size only a constant times the size of the public key. 1
Ueli Maurer
No abstract is available for this record.
Yuval Ishai, Eyal Kushilevitz, Rafail Ostrovsky, Amit Sahai
A zero-knowledge proof allows a prover to convince a verifier of an assertion without revealing any further information beyond the fact that the assertion is true. Secure multiparty computation allows n mutually suspicious players to jointly compute a function of their local inputs without revealing to any t corrupted players additional information beyond the output of the function. We present a new general connection between these two fundamental notions. Specifically, we present a general construction of a zero-knowledge proof for an NP relation $R(x,w)$, which makes only a black-box use of any secure protocol for a related multiparty functionality f. The latter protocol is required only to be secure against a small number of “honest but curious” players. We also present a variant of the basic construction that can leverage security against a large number of malicious players to obtain better efficiency. As an application, one can translate previous results on the efficiency of secure multiparty computation to the domain of zero-knowledge, improving over previous constructions of efficient zero-knowledge proofs. In particular, if verifying R on a witness of length m can be done by a circuit C of size s, and assuming that one-way functions exist, we get the following types of zero-knowledge proof protocols: (1) Approaching the witness length. If C has constant depth over $\wedge,\vee,\oplus,\neg$ gates of unbounded fan-in, we get a zero-knowledge proof protocol with communication complexity $m\cdot{poly}(k)\cdot{polylog}(s)$, where k is a security parameter. (2) “Constant-rate” zero-knowledge. For an arbitrary circuit C of size s and a bounded fan-in, we get a zero-knowledge protocol with communication complexity $O(s)+{poly}(k,\log s)$. Thus, for large circuits, the ratio between the communication complexity and the circuit size approaches a constant. This improves over the $O(ks)$ complexity of the best previous protocols.
Jameson Boex
Decentralization and intergovernmental finance have been a common element in international development efforts for many years. However, the success of fiscal decentralization as a development strategy is decidedly unclear, and there is growing skepticism about the effectiveness of (fiscal) decentralization as an international development strategy. This short essay explores the current state of knowledge with respect to fiscal decentralization and assesses the relevance of fiscal decentralization to the wider international development agenda, using the fiscal aspects of decentralization as an entry-point into the broader discussion of decentralization.
Christian Mina, Celia Reyes
The paper examines the progress being made in local finance reforms and indicates pathways to advance those reforms. A summary of the effects of decentralization is given as a contextual background for the discussion of local finance reforms. The inefficient tax assignment has constrained the mobilization of local tax revenues even as local government units have become very dependent on the intergovernmental fiscal transfer, called the internal revenue allotment. The paper raises the importance of revisiting the internal revenue allotment formula. It identifies the local finance reforms currently being undertaken and reports the progress being made at the local and national level. The final section comments on the outstanding issues in local finance reform and gives some recommendations.
Roy Bahl, Shinichi Ichimura
This book explores the important topic of fiscal decentralization in Asian countries, and focuses on how government finance and administration are being reformed to bring budgetary decisions closer to voters. The focus on Asia is especially important because all countries in this region have been undergoing serious fiscal reforms in the past decade. They include one of the biggest decentralization reforms in Indonesia, significant reforms in democratic Philippines and Vietnam which are in transition, and Japan, whose fiscal reconstruction program is covered extensively. India and China, which are also covered, are very special cases because of their size and because their policies must fit decentralization into a significant economic growth scenario.
Massimo Bordignon, Gilberto Turati
No abstract is available for this record.
Jon Wilkening
INF-SUP ESTIMATES FOR THE STOKES PROBLEM IN A PERIODIC CHANNEL JON WILKENING arXiv:0706.4082v1 [math.AP] 27 Jun 2007 Abstract. We derive estimates of the Babu˘ ka-Brezzi inf-sup constant β for two-dimensional s incompressible flow in a periodic channel with one flat boundary and the other given by a periodic, Lipschitz continuous function h. If h is a constant function (so the domain is rectangular), we show that periodicity in one direction but not the other leads to an interesting connection between β and the unitary operator mapping the Fourier sine coefficients of a function to its Fourier cosine coefficients. We exploit this connection to determine the dependence of β on the aspect ratio of the rectangle. We then show how to transfer this result to the case that h is C 1,1 or even C 0,1 by a change of variables. We avoid non-constructive theorems of functional analysis in order to explicitly exhibit the dependence of β on features of the geometry such as the aspect ratio, the maximum slope, and the minimum gap thickness (if h passes near the substrate). We give an example to show that our estimates are optimal in their dependence on the minimum gap thickness in the C 1,1 case, and nearly optimal in the Lipschitz case. Key words. Incompressible flow, Stokes equations, Babu˘ ka-Brezzi inf-sup condition, gradient, s divergence, Sobolev space, dual space AMS subject classifications. 76D03, 46E35, 42A16 1. Introduction. Many problems of industrial and biological importance in- volve fluid flow in narrow channels with moving boundaries [7, 11]. Examples include the flow of oil in journal bearings or between moving machine parts, the flow of air be- tween disk drive platters and read-write heads, or the flow of mucus under a crawling gastropod [13]. A primary objective in all these problems is to solve for the pressure required to maintain incompressibility. Indeed, it is the pressure that determines the load sustainable by a journal bearing, and that provides propulsion against viscous drag forces in peristaltic locomotion. However, only the gradient of pressure enters directly into the Stokes or Navier-Stokes equations; thus, regardless of the method used to solve the equations, the pressure must be determined via its gradient. The fundamental fact that makes it possible to extract p from ∇p is that the gradient is an isomorphism from L 2 (Ω), the space of mean-zero square integrable functions, onto the subspace of linear functionals in H −1 (Ω) 2 that annihilate the di- vergence free vector fields u ∈ H 0 (Ω) 2 ; see Section 2 below. The inf-sup constant β (or rather, its inverse) gives a bound on the norm of the inverse of this operator. Thus the magnitude of p (and our ability to estimate errors in p) depends to a large extent on the size of β −1 . However, to the author’s knowledge, every existing proof (e.g. [4, 8]) that β −1 is finite relies on Rellich’s compactness theorem to extract a sub- sequence whose lower order derivatives converge, making it impossible to determine how large β −1 might be or how it depends on Ω. The proof in [4] also uses the closed graph theorem, which, like Rellich’s theorem, leads to constants that depend on Ω in an uncontrollable way. These proofs are appropriate for pathological domains with bulbous regions connected by thin, circuitous pathways; however, for “nice domains”, it should be possible to obtain better estimates of the constants — existing theorems are of limited practical use. ∗ Department of Mathematics and Lawrence Berkeley National Laboratory, University of Cali- fornia, Berkeley, CA 94720 (wilken@math.berkeley.edu). This work was supported in part by the Director, Office of Science, Advanced Scientific Computing Research, U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Yuen H. Chan, Robert R. Taylor, Scott Markham
The intensely competitive global environment demands creative management and utilization of employees' capabilities and potentials in the organization through the use of both extrinsic and intrinsic motivational techniques (Randolph, 1995; Wischnevsky and Damanpour, 2006). Employees are expected to go that mile to adopt extra role behaviors (Organ, 1988), which are the foundation for spawning creativity and innovation. To engender such outcomes, modern managers have manipulated and changed traditional organizational context to reduce formal control and cultivate employees' self-discipline (Randolph, 1995). Key words that describe these interventions include decentralization, re-engineering, job involvement, autonomous teams and, most recently, empowerment. Generally, managers empower through interventions to eliminate social structural constraints in organizations to reduce feelings of helplessness in employees (Conger and Kanungo, 1988). Empowered employees are intrinsically motivated to take personal ownership of their jobs, to exercise self-determination, to satisfy their need for and to reinforce their personal self-efficacy beliefs (Bandura, 1986). Most empirical studies examine empowerment from the perspective of managers undertaking diverse social structural interventions to empower their subordinates (Bonnie and Bishop, 2003; Forrester, 2000; Johnson and Paper, 1998; Mills and Ungson, 2003). Spreitzer's (1995) validation of a four-factor psychological empowerment construct, however, provided the instrument for researchers to redirect their examination of empowerment to those who are being empowered (Fulford and Enz, 1995; Koberg et al., 1999; Martin and Bush, 2006; Kirkman and Rosen, 1999; Thomas and Velthouse, 1990). Although practitioners and researchers have often acknowledged that trust is a critical psychological state that determines the success of any empowerment process (Argyris, 1998; Harari, 2002; Mayer et al., 1995), little is known of the impact that empowerment interventions have on building subordinates' trust directed towards their supervisors (subordinates' trust), and the impact of subordinates' trust on the extent of psychological empowerment experienced. To address these issues, we develop a holistic nomological network model (Cronbach and Meehl, 1955) for psychological empowerment based upon the assertion that empowerment is a social exchange-driven process which requires managers to relinquish dependence on and control and instead use cooperation and facilitation in relating with their subordinates. Further, we predict that empowered employees, within the context of social exchange, will chose to reciprocate the organization with Organizational Citizenship Behaviors (OCB). THEORETICAL FRAMEWORK Relational and Psychological Empowerment Empowerment research is dominated by two different approaches. The relational approach (Burke, 1986; Champy, 1995; Karsten, 1994) examines changing relationships by the manipulation of power (Kanter, 1983). Such tools include information (technical knowledge, political intelligence, expertise), resources (funds, materials, space, time), and support (endorsement, backing, approval legitimacy). This approach assumes such empowerment interventions directly affect work-related outcomes. This conceptualization of relational empowerment has been criticized for neglecting the individuals' experiences in the empowerment process (Spreitzer, 1995; Thomas and Velthouse, 1990). Recent research has shifted focus to an individual-level construct called psychological empowerment, fueled by Spreitzer's (1995) seminal groundwork which operationalized and validated the construct. Psychological empowerment is conceptualized as the result of employees' positive cognitive assessment of their work context for meaning, self-determination, competency and impact (Spreitzer, 1995). Employees perceive meaning in an activity when the objectives of the organization are assessed to be compatible with their own value systems (Brief and Nord, 1990). …
Bruce D. Baker, Douglas R. Elmer
This article summarizes and evaluates two Off-the-Shelf school finance reforms that gained then waned in popularity over the past several years. The 65 percent solution claims that requiring all public school districts to allocate 65 cents of every education dollar “to the classroom” would drive substantial additional resources to children without increasing total spending, therefore improving the efficiency of public education systems. The 100 percent solution promotes a combination of decentralized school-based governance and budgeting, coupled with a district-to-school budget allocation strategy called Weighted Student Funding. We begin by evaluating the life cycles of these two reforms, concluding that the 65 percent solution has run its cycle, but that the 100 solution remains viable, mainly because it contains potentially more substantive reform elements. We point out that the research literature on productivity and efficiency of public schooling is far from decisive with respect to either shares of dollars allocated to the classroom or decentralized governance, despite bold claims of proponents of the solutions. Finally, we provide a series of empirical analysis and discussions of related research raising additional questions about the central claims of the reforms, including the claim that Weighted Student Funding is a panacea for funding inequities that persist across schools within large urban districts.
Joanne Xiaolei Qian, Russell Smyth
Reforms to China's education sector over the last two decades have sought to diversify the sources of funding education. This paper examines the consequences of these reforms for Chinese families and regional disparities in access to education. To illustrate the implications of education reforms for Chinese families, we draw on a large survey of urban residents across 32 Chinese cities as well as a case study of fees charged by a single secondary school in Chengdu. We argue that while China has made progress in moving towards the United Nations objective of ‘Education for All’, decentralization of China's education funding has impeded access to schooling for many, particularly those living in financially disadvantaged locales, and placed an undue financial burden on many ordinary Chinese households.
Litao Zhao
No abstract is available for this record.
Morten Skjoldborg Madsen, Martin Møller Bæk, Kongens Lyngby
www.imm.dtu.dk This thesis concerns the development of a distributed control system for a simple railway line. Control systems exist to ensure safety of trains by preventing events like derailments and collisions. Formal development methods and specification languages can increase the correctness of software systems. These methods are essential to the development of safety critical systems where human lives are at stake. Therefore a formal method is applied to the development in this thesis. A formal model, using the RAISE specification language (RSL), of a distributed control system for railway lines is developed. The formal specification language is used to ensure correctness and safety of the system. The model is separated in modules so a clear separation of the static, dynamics, and control properties is obtained. The model is constructed with provability of safety in mind. Proof obligations are sketched and the theory of how to prove safety properties in the model is briefly described. A single informal proof of one proof obligation is performed. The model is refined through a number of steps. This is done by first specifying an abstract applicative model which then is refined to a concrete version. The concrete model is transformed to an imperative version. The imperative model is implemented in the JAVA programming language. The result is a generic simulator which can take a configuration (a railway line structure) as input and simulate trains operating on this line. A configuration editor is developed to ease the construction of new railway configurations. The developed model is fairly complex compared to other formally developed models since it also concerns time issues. These complicate the model by adding a considerably larger state space to the model. Events like collisions and braking distances become major issues in the development.