In 1985, Goldwasser, Micali and Rackoff formulated interactive proof systems as a tool for developing cryptographic protocols. Indeed, many exciting cryptographic results followed from studying interactive proof systems and the related concept of zero-knowledge. Interactive proof systems also have an important part in complexity theory merging the well established concepts of probabilistic and nondeterministic computation. This thesis will study the complexity of various models of interactive proof systems. A perfect zero-knowledge interactive protocol convinces a verifier that a string is in a language without revealing any additional knowledge in an information theoretic sense. This thesis will show that for any language that has a perfect zero-knowledge proof system, its complement has a short interactive protocol. This result implies that there are not any perfect zero-knowledge protocols for NP-complete languages unless the polynomial-time hierarchy collapses. Thus knowledge comp...
Several resources relating to zero-knowledge protocols are considered. They are the number of envelopes used in the protocol, the number of oblivious transfer protocols executed during the protocol, and the total amount of communication required by the protocol. It is shown that after a preprocessing stage consisting of O(k) executions of oblivious transfer, any polynomial number of NP-theorems of any polysize can be proved noninteractively and in zero knowledge, on the basis of the existence of any one-way function, so that the probability of accepting a false theorem is less than 1/2/sup k/.>
Miguel Ángel González-Block, René Leyva Flores, OSCAR ZAP ATA, Ricardo Loewe · 5 authors
This article provides a critique of decentralization of health care systems in underdeveloped countries, taking the Mexican case as an example. The formulation, implementation and interruption of integrative decentralization in the 1980s is analysed in the context of the interests served in Mexico by administrative centralization and institutional fragmentation. The short-term results of decentralization upon state-level politics, finance, planning and health service distribution and equity are analysed in their relationship to bureaucratic and political interests. Initially the most underdeveloped region of the country was selected for a special comparative study of the effects of decentralization upon health service planning and equity. One state of this region became decentralized, while the other underwent only minor changes. It was therefore possible to compare the specific effects of administrative changes in the two states. Decentralization was interrupted at the national level, with only 14 states actually undergoing administrative change. The policy was also short of its devolutionary intentions, actually becoming an attempt towards recentralizing power around a different administrative structure. Regional disparities in the distribution of health services were accentuated due to the privileges furthered by decentralization in the richer municipalities, and the fall in services in the poorer ones related to interinstitutional conflicts at the central level
By using a technique borrowed from the inverse problem for one-dimensional motion, the proof of Bertrand’s theorem concerning the possible central forces leading to closed orbits is considerably simplified.
The problem of allocating the data of a database to the sites of a communication network is investigated. This problem deviates from the well-known file allocation problem in several aspects. First, the objects to be allocated are not known a priori; second, these objects are accessed by schedules that contain transmissions between objects to produce the result. A model that makes it possible to compare the cost of allocations is presented; the cost can be computed for different cost functions and for processing schedules produced by arbitrary query processing algorithms. For minimizing the total transmission cost, a method is proposed to determine the fragments to be allocated from the relations in the conceptual schema and the queries and updates executed by the users. For the same cost function, the complexity of the data allocation problem is investigated. Methods for obtaining optimal and heuristic solutions under various ways of computing the cost of an allocation are presented and compared. Two different approaches to the allocation management problem are presented and their merits are discussed.
In the highly centralized system of the Philippines, local funding provides the only source of flexibility to meet specific and urgent needs. The government in Manila, which pays all teacher salaries, finds it easier politically in times of fiscal belt-tightening to cut recurrent costs. Although local funds are a relatively small percentage of the education budget, they make an important contribution to covering maintenence and operating costs. The total cost of education per student also appears to lower in schools with greater local financing. Administrators and teachers have greater incentive to be cost-effective when forced to consider the effect of their behavior on the people who live and work in the local community. The policy implications of these findings for the Philippines, as well as other developing countries, are important. They strongly suggest that decentralization will increase efficiency. Without an increase in local funding, the quality of primary education will suffer.
This article contends that the German social and economic situation is conductive to the rapid diffusion of innovative medical technology. While there is public control over hospital facilities, the pluralistic health care system and decentralized government responsibilities contribute to an essentially laissez faire regulatory environment. There is perfunctory planning and regulation for major medical expenditures, but the essential constraints are financial. This is no comprehensive program for the assessment of diagnostic technologies and the effective imposition of guidelines depends on the cooperative effort of various financing organizations, professional interests, and public pressure groups.
Health Systems, Economic Evaluations, Quality of Life
Peter H. Grinyer, Peter McKiernan, Masoud Yasai‐Ardekani
Abstract Hypotheses relating to market, organizational and managerial determinants of profitability and growth are developed and tested using data collected by structured interviews in 45 randomly selected companies in the electrical engineering industry. Multiple regression analysis suggests that market share and barriers to entry are the principal determinants of profit margins, but that tightness of control of working capital and aggressive management style also have an important influence. Centralization of decision‐taking among smaller companies, too, was associated with greater profitability, whilst more extensive budgetary control and planning of acquisitions or diversification were both negatively correlated with the latter. Profitability was the single most important predictor of the rate of company growth of sales but constraints from organized labor, from sources of finance, and conservative management styles, the rate of product change, R&D intensity, and decentralization all entered significantly.
This article examines the broad spectrum of public policies and their outcomes in Western Europe and North America, in order to identify sources of success and failure, and thus determine ways of improving the effectiveness of transit subsidization. Empirical evidence suggests that decentralization of transit finance and decision making may enhance the effectiveness of subsidies. Transit subsidies are as important as government policies affecting the costs of auto ownership and use. In the United States large transit subsidies have led to negligible ridership growth and no increase in the proportion of tripmaking by mass transit. Greater decentralization of decision making and financing might be an approach to increasing its effectiveness.
To this point, our conception of the mixed economy has treated the public sector as monolithic. However, we observe a considerable degree of government decentralization in practice, and indeed, we would expect to find some such structures in a second-best organizational design for much the same reasons we argued for market decentralization of private goods earlier. Here, we will develop a model of government structure that is roughly consistent with the actual organization of the U.S. public sector. We will emphasize normative properties of this structure, drawing on earlier discussions of political decentralization and mechanism design. One possible approach to public-sector design would be to mimic closely the structure of market decentralization. That is, we could divide up responsibilities into a large collection of fully autonomous agencies, each of which would be responsible for the allocation of a narrow range of collective goods. Autonomy would be achieved by having each individual agency elicit information on preferences and assess separate taxes and/or user charges. To the extent that “true” information is learned, it can be used to organize finance according to the so-called benefits principle – household payments for the collective goods and services would be directly related to benefits received. This mode of organization has many desirable features. First and foremost, it eliminates entirely the need for centralized information gathering and the associated cost of bureaucracy needed to administer and coordinate activities. Further, to the extent that the finance tax can be made a charge for services rendered, it will act like a price that will induce the relevant clientele to reveal their preferences.
The authors present the design, implementation, and testing of the critical path analysis technique using the IPS performance measurement tool for parallel and distributed programs. They create a precedence graph of a program's activities (program activity graph) with the data collected during the execution of a program. The critical path, the longest path in the program activity graph, represents the sequence of the program activities that take the longest time to execute. Various algorithms are developed to track the critical path from this graph. The events in this path are associated with the entities in the source program, and the statistical results are displayed on the basis of the hierarchical structure of the IPS. The test results from the measurement of sample programs show that the knowledge of the critical path in a program's execution helps users identify performance problems and better understand the behavior of a program.>
Innovative Flexible Interior Gas Distribution Systems R.N. Torbin; R.N. Torbin Foster-Miller Inc. Search for other works by this author on: This Site Google Scholar M. Wilkey; M. Wilkey Gas Research Inst. Search for other works by this author on: This Site Google Scholar P. Belkus P. Belkus Foster-Miller Inc. Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Gas Technology Symposium, Dallas, Texas, June 1988. Paper Number: SPE-17737-MS https://doi.org/10.2118/17737-MS Published: June 13 1988 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Torbin, R.N., Wilkey, M., and P. Belkus. "Innovative Flexible Interior Gas Distribution Systems." Paper presented at the SPE Gas Technology Symposium, Dallas, Texas, June 1988. doi: https://doi.org/10.2118/17737-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Unconventional Resources Conference / Gas Technology Symposium Search Advanced Search AbstractThe Gas Research Institute (GRI) is funding research to investigate alternative gas piping technologies which can make gas service as easy to install as electric service. The semirigid tubing systems being evaluated are soft copper tubing and a Japanese product, corrugated stainless steel tubing (CSST). Both use mechanical fittings and are designed to operate using either traditional low pressure (8 in. of water column (WC)) or a special hybrid pressure (2 psi and 8 in. WC) approach. This research has been conducted at several different single family and multifamily buildings located throughout the United States.Results from these sites indicate that regardless of the building type, semirigid tubing systems can be installed in less time and usually at lower cost than conventional steel pipe systems. The labor savings vary between 30 and 70 percent, while the cost savings vary between 10 and 50 percent. The use of these semirigid tubing systems also makes a decentralized gas distribution system more viable.BackgroundIn 1983, GRI began its Residential/Commercial Interior Piping Research Program. The first activity completed by GRI's research contract, Foster-Miller, Inc., was to determine the state of the art of interior gas piping systems found both in the United States and abroad. Subsequently, Foster-Miller developed an. optimized gas distribution system for the United States housing market based on commercially available piping technology.The most commonly used interior gas distribution system in the world is a series/branch arrangement using Schedule 40 steel pipe with threaded joints operated at low pressure (nominally 8 in. WC). Copper (either as semirigid tube or rigid pipe) is used in several countries for interior gas distribution, but far less frequently than steel pipe. The most innovative hardware discovered in the review is a CSST system with special mechanical fittings used exclusively in Japan. One innovative approach to the interior gas distribution was found in the United States, where copper tubing systems are operated at 2 psi pressure. Gas utilities using these semirigid (copper or CSST) tubing systems (both at low pressure and 2 psi) report cost reductions in the total installed cost when compared with the equivalent steel pipe system.Both the copper and the CSST systems have several advantages. The flexible nature of the tubing allows the system to be installed with a significant reduction (over the traditional steel pipe) in labor; the tubing is supplied in coils allowing long, continuous runs to be installed; thus minimizing the number of joints. Since there are fewer system components to handle, the overall installation time is less. -The semirigid tubing is easily snaked through or around existing structural obstacles which are typically faced when field-run systems are installed. Since the tubing components are lightweight, fewer installers are needed, with less effort required of the installers during installation.A series of initial field tests were completed at two single family sites. During these studies, the current installation practices and piping hardware were evaluated.P. 325^ Keywords: csst system, installation time, upstream oil & gas, installer, semirigid, installation, appliance, real estate, banking & finance, michigan city Subjects: Pipelines, Flowlines and Risers, Piping design and simulation This content is only available via PDF. 1988. Society of Petroleum Engineers You can access this article if you purchase or spend a download.
The prosecution of George Reynolds in the mid-1870s and the United States Supreme Court's 1879 affirmation of that conviction are usually viewed as the key legal events leading to mass prosecution of Mormon polygamists in the late 1880s.While Reynolds v. the United States (1879) seemed to dispose of the crucial first amendment defense relied upon by the Mormons, it did not lead to the prosecutions.Rather, they were triggered by the passage of thé Edmunds Act in 1882 as well as a major Supreme Court decision in 1885 over the cohabitation prosecution of Salt Lake Stake President Angus M. Cannon.When Reynolds was first prosecuted in 1875 there was no crime of cohabitation on the federal statute books.Only polygamy was a crime and could not be prosecuted without proof of a marriage ceremony, evidence almost impossible for prosecutors to secure.Enforcement of the anti-polygamy laws in Utah was a "dead letter."At least until 1885 and the Angus Cannon prosecution.When Brigham Young and Orson Pratt delivered the first public sermons on polygamy in August 1852 (Arlington 1985, 226; Van Wagoner 1986, 84), they were making public a principle revealed to Joseph Smith, Jr., in 1843 (D&C 132) but practiced with the greatest secrecy (Van Wagoner 1986, 1-69;Foster 1974).The sermons set in motion events that resulted in forty years of confrontation with the federal government and would threaten the Church's very existence.In spite of later national outrage, it was apparently not a crime in the early Utah Territory for a man to marry more than one woman at a time.
Abstract Since Botswana became independent in 1966 a steady process of decentralization has been undertaken by a Botswana Democratic Party (BDP) government confident in its own legitimacy and committed officially to a policy of rural development. In 1978 the President appointed a Local Government Structure Commission to test the suitability of the existing structure and to advise on the relationship between the four main institutions at district level–the District Administration, the District Council, the Land Board and the Tribal Administration. In its 1979 Report the Commission recommended that each institution should retain its separate identity, with its powers balanced by those of the others. This article reviews the working of each institution, and concludes that the Commission's recommendation was justified. It notes, however, that the balance between the four institutions has been tilted to an extent in favour of the District Administration. It shows that the District Councils have displayed an improved capacity for plan implementation, but need more skilled technical personnel and a better quality of elected councillor; that the Land Boards are no longer subordinate to the District Councils in administrative matters, but are hampered by a shortage of transport and finance; and that Tribal Administration staff still work under very poor conditions, though their salaries and pensionable status are much improved.
Suppose an associate handed you a 500 digit number N, and informed you, know the prime factorization of N. What would convince you of the truth of your associate's statement?
If your associate could be persuaded to reveal the factorization to you, a few simple tests would convince you of the statement's truth. Unfortunately the associate responds to this request by saying, factorization is a secret. In fact, I would like to convince you that I know the factorization of N without divulging any other useful information. How can you hope to be convinced that your associate is not deceiving you? Needless to say, a primality testing algorithm quickly reveals N to be composite, but your favorite factorization algorithms make no progress whatever.
These seemingly irreconcilable positions (the associate's unwillingness to reveal any knowledge, your unwillingness to accept your associate's statement without proof) are reconcilable through a protocol known as a zero interactive proof, introduced by Goldwasser, Micali, and Rackoff [15] in 1985. Informally, an interactive proof is a pair of protocols executed by two parties, called the and the whereby the prover attempts to convince the verifier of the validity of some proposition II. The prover, even by deviating from its protocol, should not be able to convince the verifier of the truth of II if, in fact, II is false. An interactive proof is zero knowledge if the verifier, even by deviating from its protocol, cannot gain any information from the prover (other than the validity of II) that it could not have derived efficiently itself. More specifically, for any verifier that outputs after interacting with the prover, there is an algorithm that, without benefit of interacting with the prover, produces outputs from a distribution indistinguishable from that of the verifier.
The interested reader can find careful definitions of these notions in [20]. The particular problem of of factorization will be left on the hook until the last section. The intervening sections contain some interesting historical digressions.