From a societal point of view, it is difficult to determine whether a centralized or decentralized health system is superior. A normative statement of that kind entails substantial value judgments and trade-offs. No two health care systems are identical, although many share characteristics that allow us to develop typologies which are useful in analysis of any particular system. Third parties make the health care system much more complex because the source of third-party financing and the method of reimbursement must be worked into the model. The Socialized Health Insurance Program (SI) in Germany is based on government mandated financing by employers and employees. The essential features of the Canadian health care system are national insurance, free choice of health care provider, private production of medical services, and regulated global budgets and fees for health care providers. The United States health care system is the expensive in the world but under-performs relative to many peer countries on most dimensions of performance.
Abstract Disease surveillance, especially for infectious diseases, is a complex and inefficient process. Here we propose an optimized, blockchain-based monitoring and reporting process which can achieve all the desired features of an ideal surveillance system while maintaining costs down and being transparent and robust. We describe the technical specifications of such a solution and discuss possibilities for its implementation. Finally, the impact of the adoption of distributed ledger technology for disease surveillance is discussed.
This article suggests that the worldwide relevance of blockchain technology is motivated by the changes that it is expected to cause in: (i) the way that business is organised and (ii) regulated, as well as (iii) by the way that it changes the role of individuals within a society. The article presents an overview of the features of blockchain technology. It then takes a closer look into the developments within the energy sector across the world to gain a preliminary indication of whether the stated expectations are coming to reality. As a result of this review, we remain cautiously optimistic that blockchain technology could deliver the expected impact.
We empirically verify that the market capitalizations of coins and tokens in the cryptocurrency universe follow power-law distributions with significantly different values for the tail exponent falling between 0.5 and 0.7 for coins, and between 1.0 and 1.3 for tokens. We provide a rationale for this, based on a simple proportional growth with birth and death model previously employed to describe the size distribution of firms, cities, webpages, etc. We empirically validate the model and its main predictions, in terms of proportional growth (Gibrat's Law) of the coins and tokens. Estimating the main parameters of the model, the theoretical predictions for the power-law exponents of coin and token distributions are in remarkable agreement with the empirical estimations, given the simplicity of the model. Our results clearly characterize coins as being 'entrenched incumbents' and tokens as an 'explosive immature ecosystem', largely due to massive and exuberant Initial Coin Offering activity in the token space. The theory predicts that the exponent for tokens should converge to 1 in the future, reflecting a more reasonable rate of new entrants associated with genuine technological innovations.
We empirically verify that the market capitalisations of coins and tokens in the cryptocurrency universe follow power-law distributions with significantly different values, with the tail exponent falling between 0.5 and 0.7 for coins, and between 1.0 and 1.3 for tokens. We provide a rationale for this, based on a simple proportional growth with birth & death model previously employed to describe the size distribution of firms, cities, webpages, etc. We empirically validate the model and its main predictions, in terms of proportional growth (Gibrat's law) of the coins and tokens. Estimating the main parameters of the model, the theoretical predictions for the power-law exponents of coin and token distributions are in remarkable agreement with the empirical estimations, given the simplicity of the model. Our results clearly characterize coins as being "entrenched incumbents" and tokens as an "explosive immature ecosystem", largely due to massive and exuberant Initial Coin Offering activity in the token space. The theory predicts that the exponent for tokens should converge to 1 in the future, reflecting a more reasonable rate of new entrants associated with genuine technological innovations.
Shuqing Bian, Zhenpeng Deng, Fei Li, Will Monroe · 12 authors
Cryptocurrencies (or digital tokens, digital currencies, e.g., BTC, ETH, XRP, NEO) have been rapidly gaining ground in use, value, and understanding among the public, bringing astonishing profits to investors. Unlike other money and banking systems, most digital tokens do not require central authorities. Being decentralized poses significant challenges for credit rating. Most ICOs are currently not subject to government regulations, which makes a reliable credit rating system for ICO projects necessary and urgent. In this paper, we introduce IcoRating, the first learning--based cryptocurrency rating system. We exploit natural-language processing techniques to analyze various aspects of 2,251 digital currencies to date, such as white paper content, founding teams, Github repositories, websites, etc. Supervised learning models are used to correlate the life span and the price change of cryptocurrencies with these features. For the best setting, the proposed system is able to identify scam ICO projects with 0.83 precision. We hope this work will help investors identify scam ICOs and attract more efforts in automatically evaluating and analyzing ICO projects.
Decentralization reforms and rapid urbanization place increasing pressure on African urban authorities. In response, land-based finance has been gaining popularity within development discourses as a method of increasing local autonomy and financing local government infrastructure provision. This paper discusses the conceptual basis for land-based finance, the instruments that form part of this approach, and the actual application in several African cities. Drawing on three case studies (Addis Ababa, Harare and Nairobi) and a high-level scan of 29 developments in various African cities, we show how land-based finance is being implemented in practice and discuss the potential for wider uptake. We conclude that African city governments are using land-based financing, albeit in inconsistent ways. We argue that urban authorities should consider the more extensive and progressive use of land-based financing instruments, despite the constraints imposed by both technical and political conditions. A progressive agenda for local government finance in African cities should take land-based finance seriously, as well as the local practices and institutional arrangements through which it operates.
Over the last few years, research on Bitcoin and other cryptocurrencies has snowballed across many disciplines: technical fields, economics, law, public policy, finance, accounting, and others. As the uses of blockchain technology behind Bitcoin expand, more disciplines will be drawn to its study and the research will greatly expand. This paper provides an assessment of the current state of the literature. From a comprehensive search of the literature that resulted in an original sample of 13,507 results, a final sample of 1,206 papers on Bitcoin are categorised and mapped across six disciplines.
Shayan Eskandari, Andreas Leoutsarakos, Troy Mursch, Jeremy Clark
In this paper, we examine the recent trend towards in-browser mining of cryptocurrencies; in particular, the mining of Monero through Coinhive and similar code- bases. In this model, a user visiting a website will download a JavaScript code that executes client-side in her browser, mines a cryptocurrency, typically without her consent or knowledge, and pays out the seigniorage to the website. Websites may consciously employ this as an alternative or to supplement advertisement revenue, may offer premium content in exchange for mining, or may be unwittingly serving the code as a result of a breach (in which case the seigniorage is collected by the attacker). The cryptocurrency Monero is preferred seemingly for its unfriendliness to large-scale ASIC mining that would drive browser-based efforts out of the market, as well as for its purported privacy features. In this paper, we survey this landscape, conduct some measurements to establish its prevalence and profitability, outline an ethical framework for considering whether it should be classified as an attack or business opportunity, and make suggestions for the detection, mitigation and/or prevention of browser-based mining for non- consenting users.
Blockchain serving as an unalterable ledger, has received widespread attentions recently, which allows carrying out transactions with a decentralized matter. Applications with blockchain technology are springing up. However, financial applications especially in bank liquidation system are still facing big challenges. This paper first presents a consensus combined delegated-proof-of-stake protocol and BFT algorithm together. At the same time, using parallel idea and redesigned blockchain structure make the system more efficiency.
In the Indonesian constitutional Autonomous Region is an elaboration of territorial decentralization. Realization in the form of the rights, powers and obligations of the region to regulate and manage its own internal affairs are based on the aspirations of the people in accordance with the legislation in force. One of the objectives scrolling regional autonomy policy in Indonesia is Democratization, empowerment and public participation. To achieve this, then the government has a policy of decentralization in stages, namely the provinces given limited autonomy, greater autonomy to the district / city and country are given genuine autonomy. Community participation is a process activities performed by individuals or in groups or communities. To unify their interest or relevance to the organization or people who join in order to achieve the objectives of society itself. This study uses descriptive qualitative research methods From the results of this study, researchers found that community participation in Jatimulya village influenced by the leadership, communication and education. The result showed that the head of the village has been carrying out its role as the leader of a well, the village government communication with the public is well established and low education affects people’s participation in development planning in the Jatimulya Villa. Dalam ketatanegaraan Indonesia Otonomi Daerah merupakan penjabaran dari desentralisasi teritorial. Realisasinya dalam bentuk hak, wewenang dan kewajiban daerah untuk mengatur dan mengurus urusan rumah tangga sendiri yang berdasarkan atas aspirasi masyarakat sesuai dengan peraturan perundang-undangan yang berlaku. Salah satu tujuan pengguliran kebijakan Otonomi Daerah di Indonesia adalah Demokratisasi, Pemberdayaan dan Partisipasi publik. Untuk mencapai hal tersebut maka pemerintah menggulirkan kebijakan desentralisasi secara bertingkat, yakni kepada provinsi diberikan otonomi terbatas, otonomi luas kepada daerah kabupaten/kota dan Desa diberikan otonomi asli. Partisipasi masyarakat merupakan suatu proses kegiatan yang dilakukan oleh perorangan maupun secara berkelompok atau masyarakat. Untuk menyatukan kepentingan atau keterkaitan mereka terhadap organisasi atau masyarakat yang bergabung dalam rangka pencapaian tujuan masyarakat itu sendiri. Penelitian ini menggunakan metode penelitian deskriptif kualitatif. Dari hasil penelitian di dapatkan bahwa partisipasi masyarakat di Desa Jatimulya di pengaruhi oleh kepemimpinan, komunikasi dan pendidikan. Dari hasil penelitian diperoleh bahwa kepala Desa telah melaksanakan perannya sebagai pemimpin dengan baik, komunikasi pemerintah Desa dengan masyarakat terjalin dengan baik dan rendahnya pendidikan masyarakat mempengaruhi partisipasi dalam perencanaan pembangunan di Desa Jatimulya
Rolf van Wegberg, J.J. Oerlemans, Oskar van Deventer
Purpose -This paper aims to shed light into money laundering using bitcoin. Digital payment methods are increasingly used by criminals to launder money obtained through cybercrime. As many forms of cybercrime are motivated by profit, a solid cash-out strategy is required to ensure that crime proceeds end up with the criminals themselves without an incriminating money trail. The authors examine how cybercrime proceeds can be laundered using services that are offered on the Dark Web.
A cycle of elliptic curves is a list of elliptic curves over finite fields such that the number of points on one curve is equal to the size of the field of definition of the next, in a cyclic way. We study cycles of elliptic curves in which every curve is pairing-friendly. These have recently found notable applications in pairing-based cryptography, for instance in improving the scalability of distributed ledger technologies. We construct a new cycle of length 4 consisting of MNT curves, and characterize all the possibilities for cycles consisting of MNT curves. We rule out cycles of length 2 for particular choices of small embedding degrees. We show that long cycles cannot be constructed from families of curves with the same complex multiplication discriminant, and that cycles of composite order elliptic curves cannot exist. We show that there are no cycles consisting of curves from only the Freeman or Barreto--Naehrig families.
BOU Council feels that the continued existence of national groups, each understandably feeling an obligation to retain control of the taxonomy used for their own national lists, is not in the best interests of ornithology and is a barrier preventing the establishment of a unified European taxonomy (https://www.bou.org.uk/british-list/taxonomy/). the scientific community's failure to govern taxonomy threatens the effectiveness of global efforts to halt biodiversity loss, damages the credibility of science and is expensive to society (Garnett & Christidis 2017). It is hard not to sympathize: surely nobody welcomes or benefits from mismatches between taxonomies (taxonomy being the phylogenetic classification of living organisms; mismatches can also occur as a problem of nomenclature – the rules-based system of assigning names in phylogenetic classifications – but this is not the issue under consideration here). Uniformity and agreement – harmony and homogeneity – on regional and indeed global taxonomic scales are sensible, desirable and perhaps even achievable goals, and ostensibly it follows that we should take or support all reasonable measures to reach them. In ornithology, four world lists are now, in Garnett & Christidis's view, ‘competing for legitimacy’: two long-established and constantly evolving works which take their names from their founders, ‘Howard & Moore’ (Dickinson & Remsen 2013, Dickinson & Christidis 2014) and ‘Clements’ (Clements et al. 2017), and two more recent offerings, the online-only International Ornithological Congress (IOC) list (Gill & Donsker 2017) and the HBW-BirdLife illustrated checklist (del Hoyo & Collar 2014, 2016). Each has its legitimacy already. ‘Howard & Moore’ enjoys universal respect for its pioneering attention to matters of nomenclatural priority. ‘Clements’, twinned with eBird, serves an ever-expanding community of birdwatchers. IOC enjoys the cachet of the foremost global ornithological institution. Finally, HBW-BirdLife forms the basis for the IUCN Red List and the ‘HBW Alive’ online resource. Garnett and Christidis illustrate their argument with a graph labelled ‘Mix ‘n’ Match’ which shows the widely discrepant totals of species that these four lists recognize, ‘mostly because they use different definitions for what constitutes a species’. I think this last point is largely mistaken. What unites the lists is far greater than what divides them; and what divides them may perhaps be less to do with fundamental disagreements over species definitions than with working schedules and systems. The HBW-BirdLife list, which in Garnett & Christidis's graph shows a sudden sharp leap in species recognized in 2016 (from under 10 500 to over 11 000, including extinct forms), is merely the product of a proactive application of a set of criteria to the global avifauna in a way which the other lists have not sought to emulate. In due course, however, some at least of the HBW-BirdLife changes may well be adopted by the others, particularly if validated by independent study, as in the cases of (among others) Lesser Crescent-chested Puffbird Malacoptila minor (Ferreira et al. 2017), Lesser Sri Lanka Flameback Dinopium psarodes (Fernando et al. 2016), Turquoise-winged Parrotlet Forpus spengeli (Bocalini & Silveira 2015) and Peruvian Pipit Anthus peruvianus (van Els & Norambuena 2018). But there is something else that divides them, of course: pride, the first and worst of the seven deadly sins (I display it simply in rolling out the list of confirmed splits above). The pride people take in their work is the best of it, but this seemingly irreproachable quality links directly to that irrational loyalty and partisanship we all show to the various institutions – family and faith, country and college, football teams and fashion-houses – in which we human beings have a deep emotional stake. In science this tribal mindset is kept in check by the demand for evidence and proof, the scrutiny of peer-review and the expectation of replicability. Taxonomy, however, is at the looser end of science, where facts need the ample mediation of human judgement, belief and opinion to become meaningful. Consequently, if you question someone's taxonomy, you question their authority, even their identity; and everything suddenly becomes rather tense and personal. Simply therefore for reasons of professional pride – why make all that effort only to let someone else overrule your considered decisions? – authors/editors of the four lists will naturally, inevitably, want theirs to prevail. Even so, one thing that largely unites the four lists (although IOC is unique in remaining silent on the conceptual framework of its species-rank decision-making) is their discomfort with the phylogenetic species concept (PSC), perhaps the greatest difficulty with which concerns the constant potential for subdivision of taxa as their populations are found to exhibit smaller and smaller diagnosable differences (Mace et al. 2003). Recent research has postulated the existence of 1.97 phylogenetic species per biological species of bird, thereby increasing the global total of ‘species’ under that concept to 18 043, with a confidence interval of 15 845–20 470 (Barrowclough et al. 2016). It is perhaps the width of that confidence interval, reflecting so much uncertainty and indicating the need for so many years of work to reduce it, that most entitles the authors/editors of world lists to confine the PSC to the sidelines of avian taxonomy; and for the most part they exclude species defined solely under that concept from consideration. Yet is this not to replace individual tribalist loyalties with a form of collective tyranny? It is hardly as if we want to deny the existence of the kinds of variation that PSC-driven analyses identify, or set them aside as inconveniences. The Barrowclough study is an important reminder of the biological diversity that exists within what we currently label species and it is wholly legitimate to seek to enumerate and recognize it. In fact, one of the most exhilarating and simultaneously depressing aspects of the modern surge in molecular phylogenetic studies is the way new and unexpected characterizations of species keep emerging (exhilarating for obvious reasons, depressing because it so often adds new burdens on the shoulders of conservationists already staggering under the weight of their responsibilities). We are increasingly discovering that avian populations, from boreal waders and oceanic seabirds to passerine migrants and tropical residents, are subtly adapted to local conditions – the Hawaiian Petrel Pterodroma sandwichensis differs morphometrically on each breeding island (Judge et al. 2014), Red-necked Nightjars Caprimulgus ruficollis are larger in one breeding habitat than another (Camacho et al. 2016) – and the ‘implications for conservation’ (a subheading that is becoming standard at the ends of modern taxonomic papers) are, collectively, enormous. In truth, it is not just conservationists who are staggering under the strain of all these new insights: the sheer volume of research into variation within bird species published in the course of the present century has also overwhelmed the authors/editors of the world checklists. The Introduction in del Hoyo and Collar (2016) records that publications on passerine taxonomy alone appeared at the rate of 0.5 per working day for the 6½ years between the start and the end of the HBW-BirdLife publication project. This level of pressure is in my view far too great to permit dependable or stable decisions (which are likely to be made either too quickly or not quickly enough) and consequently no-one and no cause is well served. If there are reasons to lament the passing of the BOU Taxonomic Sub-committee, this is one of the best: to act as a point of reference on the content and import of some of these publications, helping to ensure they are not overlooked and to clarify their worth. Sifting through myriad papers to assess the taxonomically transformative outcomes their authors claim they produce is a long and lonely business. Being able to cross-refer to other reviews, irrespective of their standpoint or conclusions, as a means of discovering and shaping one's own thought and position, was and remains hugely helpful. … vagueness is not compatible with conservation. To protect biodiversity, laws need to compartmentalize it, and those compartments must have legally defensible boundaries. Having myself sought to create such boundaries (Tobias et al. 2010) and ended essays on the same point about law (Collar 1997, 2013), I naturally warm to Garnett & Christidis for their unflinching forthrightness, but I suspect that many members of the avian taxonomic community – see Raposo et al. (2017) for early evidence – will sense the spectre of tyranny (‘restrict the freedom of taxonomic action’!) animating so revolutionary an idea as a single global authority to pass judgement on their work. Moreover, ‘legally defensible boundaries’ for species may take some time to be acknowledged as a necessity, and much longer to be agreed. Beyond the class Aves it is entirely normal for species to be delineated by molecular means only, although not without scepticism (e.g. Monaghan & Sartori 2009). Within ornithology, the BOU Taxonomic Sub-committee laudably sought to make progress in this area 15 years ago, but the resulting ‘guidelines’ (Helbig et al. 2002), involving a set of uninterpretable ambiguities and partial definitions, could not be made to work when applied to uncontentious European taxa (Collar 2013). This failure was in fact the spur to the development of the criteria in Tobias et al. (2010), which were used as the basis for the taxonomic decision-making in del Hoyo and Collar (2014, 2016). It would seem that Garnett & Christidis's requirement almost inevitably predicates very similar criteria, involving multiple phenotypic characters and yielding accountable transparent results. Laws take time to draw up, pass and train people to enforce – this is a crucial circumstance that the zoological community must grasp – so one might expect real resistance to the use of weaker criteria or lower thresholds than those in Tobias et al. if they risk producing outcomes more open to challenge and reversal. However, lower thresholds will still be needed for ‘other taxonomic units’. Infraspecific variation urgently needs a standardized system of classification, precisely in order to capture the biological diversity to which Barrowclough et al. (2016) draw attention; the eBird-Clements, Howard & Moore and HBW-BirdLife lists all make informal gestures in this direction by identifying ‘subspecies groups’, but much more work is required to bring rigour and coherence to the issue (although here again the Tobias criteria could perhaps make a useful contribution). At present, definitions of subspecies are far from fixed; and even molecular scientists cannot always agree over process and evidence (e.g. Zink et al. 2013, 2016, McCormack & Maley 2015, Patten 2015). There is, however, little point in establishing any of these ‘boundaries’ unless they can then be used on the global avifauna with sufficient speed for conservation – which is Garnett and Christidis's (2017) guiding consideration – to benefit. On the other hand, the manpower required to reassess the global avifauna – let alone all the other faunas of the planet – and keep pace with the relentless march of new publications cannot come without a significant cost. At present, the four world checklists fund themselves, and their work is undertaken on budgets that are dwarfed by the investments in molecular research around the world which produce most of the studies the checklists have to deal with. Garnett and Christidis mention that the International Commission on Zoological Nomenclature (ICZN), on which we all depend for final arbitration on the scientific names of animals, is a branch of IUBS, the body to which they propose to transfer all taxonomic authority, but they do not mention that ICZN recently had to be rescued from major financial difficulties by the National University of Singapore (Normile 2013). If it is true that the scientific community's failure to govern taxonomy is ‘expensive to society’, someone needs to muster the evidence to convince ‘society’ to cut its losses in one area by investing wisely in another. The final and most important issue is, of course, how a new commission could be created that will possess the internal resilience – impartiality, scholarship, industry, capacity, finance – to function efficiently as the ultimate taxonomic arbiter of the measurement of biological diversity. Given the almost inconceivable spectrum of that diversity, it is hard not to think that the commission's first action would be to collapse under the weight of its own remit; the spectre of tyranny might yet be banished, but the distinction between inertia and intolerance is not obvious when answers are urgently needed. At any rate, barring some remarkable generosity by a host government or major foundation, it seems wholly improbable that progress will be made any time soon. Still, if Garnett & Christidis's idea has traction, could the birds perhaps lead the way? Should the ornithological community attempt to build a cut-price prototype, whether under the aegis of IUBS or not? The four world checklists are, as noted, buckling under the burden and, if nothing more, well out of sync and half out of pocket. Could it be time for them to disband and pool their pride in a new venture to approach their task afresh and work towards the goal Garnett & Christidis have set? The editors/authors of the four checklists have already, without external prompting, held friendly talks to explore the issue. The most obvious challenges are to agree what might constitute ‘legally defensible boundaries’, to develop a process that is consistent, fair and robust, and to address the fact that none of the persons involved has a mandate from the ornithological community to undertake the work in question. If I can see the benefits of a unified list, I cannot forget my debt to the BOU Taxonomic Sub-committee and other such bodies: it will be crucial to the enterprise that it is understood to be driven by a spirit of goodwill that acknowledges – and even draws strength from – the diversity of taxonomic standpoints, and not by delusions of global hegemony. This needs some thought. Learned ornithological societies might provide neutral ground, independent advice and intellectual input that would help decide the framework, the constitution and the schedule (a 4-year cycle geared to the IOC perhaps) under which such a collaboration could flourish. The financial resources of the four checklists might be combined and, if possible, supplemented. Some or all of the editors/authors might need to recuse themselves or at least seek the approval of authorities representing ‘the best interests of ornithology’; and they, too, would surely need to be supplemented. Above all, to give this initiative to synthesize a single world list of birds the chance of lasting long enough to confer any recognizable benefit to society, the resulting taxonomy will have to be widely and rightly perceived as the offering of a scrupulously observant democracy and not the imposition of a heedless and self-serving tyranny. Stuart Butchart, Lincoln Fishpool, Josep del Hoyo, Guy Kirwan and Robert Prys-Jones very helpfully commented on the first draft of this note.
The study aims to determine the opinions of school principals on decentralization in education. Phenomenological research design was used in the study. The purposive sampling methods of convenience and criterion samplings were used together. The study group was composed of six volunteer principals. The data were collected through individual face-to-face interviews using a semi-structured form. Descriptive analysis and inductive content analysis were used. In conclusion, from a holistic perspective, most of the participants found the concept of decentralization to be close to full autonomy which is usually perceived as dangerous in terms of the unitary state structure. Therefore, they have more centralized attitudes towards educational processes other than financing and infrastructure support regarding decentralization in education. This is indeed an indication that concerns regarding decentralization in education are high. The participants think that decentralization will not harm our national identity and the national education structure is beneficial.
Regional autonomy is being discussed in Latin America as one of several proposals for resolving the indigenous issue. As a political collectivity, an autonomous community or region is established as a component of the corresponding nation-state. Autonomy seeks not only to satisfy the interests and aspirations of partial communities but to ensure a more adequate integration of the national society. The regime of regional autonomy is a response to the need to ensure democratic representation of the country&s;s sociocultural regions within the state&s;s political and administrative organization in a way compatible with the plural ethnic-national makeup of the society. In these terms, regional autonomy implies a certain political and administrative decentralization of the state. The decentralization brought about by autonomy is juridical-political rather than simply administrative. It depends on the law rather than on the assignment or transfer of functions by a higher administrative organ that can also revoke them.
Alessandro Chiesa, Michael A. Forbes, Tom Gur, Nicholas Spooner
Zero knowledge plays a central role in cryptography and complexity. The seminal work of Ben-Or et al. (STOC 1988) shows that zero knowledge can be achieved unconditionally for any language in NEXP , as long as one is willing to make a suitable physical assumption : if the provers are spatially isolated, then they can be assumed to be playing independent strategies. Quantum mechanics, however, tells us that this assumption is unrealistic, because spatially-isolated provers could share a quantum entangled state and realize a non-local correlated strategy. The MIP * model captures this setting. In this work, we study the following question: Does spatial isolation still suffice to unconditionally achieve zero knowledge even in the presence of quantum entanglement? We answer this question in the affirmative: we prove that every language in NEXP has a 2-prover zero knowledge interactive proof that is sound against entangled provers; that is, NEXP ⊆ ZK-MIP * . Our proof consists of constructing a zero knowledge interactive probabilistically checkable proof with a strong algebraic structure, and then lifting it to the MIP * model. This lifting relies on a new framework that builds on recent advances in low-degree testing against entangled strategies, and clearly separates classical and quantum tools. Our main technical contribution is the development of new algebraic techniques for obtaining unconditional zero knowledge; this includes a zero knowledge variant of the celebrated sumcheck protocol, a key building block in many probabilistic proof systems. A core component of our sumcheck protocol is a new algebraic commitment scheme, whose analysis relies on algebraic complexity theory.
Online portals include an increasing amount of user feedback in form of ratings and reviews. Recent research highlighted the importance of this feedback and confirmed that positive feedback improves product sales figures and thus its success. However, online portals' operators act as central authorities throughout the overall review process. In the worst case, operators can exclude users from submitting reviews, modify existing reviews, and introduce fake reviews by fictional consumers. This paper presents ReviewChain, a decentralized review approach. Our approach avoids central authorities by using blockchain technologies, decentralized apps and storage. Thereby, we enable users to submit and retrieve untampered reviews. We highlight the implementation challenges encountered when realizing our approach on the public Ethereum blockchain. For each implementation challange, we discuss possible design alternatives and their trade-offs regarding costs, security, and trustworthiness. Finally, we analyze which design decision should be chosen to support specific trade-offs and present resulting combinations of decentralized blockchain technologies, also with conventional centralized technologies.