Price stability has often been cited as a key reason that cryptocurrencies have not gained widespread adoption as a medium of exchange and continue to prove incapable of powering the economy of decentralized applications (DApps) efficiently. Exeum proposes a novel method to provide price stable digital tokens whose values are pegged to real world assets, serving as a bridge between the real world and the decentralized economy. Pegged tokens issued by Exeum - for example, USDE refers to a stable token issued by the system whose value is pegged to USD - are backed by virtual assets in a virtual asset exchange where users can deposit the base token of the system and take long or short positions. Guaranteeing the stability of the pegged tokens boils down to the problem of maintaining the peg of the virtual assets to real world assets, and the main mechanism used by Exeum is controlling the swap rate of assets. If the swap rate is fully controlled by the system, arbitrageurs can be incentivized enough to restore a broken peg; Exeum distributes statistical arbitrage trading software to decentralize this type of market making activity. The last major component of the system is a central bank equivalent that determines the long term interest rate of the base token, pays interest on the deposit by inflating the supply if necessary, and removes the need for stability fees on pegged tokens, improving their usability. To the best of our knowledge, Exeum is the first to propose a truly decentralized method for developing a stablecoin that enables 1:1 value conversion between the base token and pegged assets, completely removing the mismatch between supply and demand. In this paper, we will also discuss its applications, such as improving staking based DApp token models, price stable gas fees, pegging to an index of DApp tokens, and performing cross-chain asset transfer of legacy crypto assets.
Price stability has often been cited as a key reason that cryptocurrencies\nhave not gained widespread adoption as a medium of exchange and continue to\nprove incapable of powering the economy of decentralized applications (DApps)\nefficiently. Exeum proposes a novel method to provide price stable digital\ntokens whose values are pegged to real world assets, serving as a bridge\nbetween the real world and the decentralized economy.\n Pegged tokens issued by Exeum - for example, USDE refers to a stable token\nissued by the system whose value is pegged to USD - are backed by virtual\nassets in a virtual asset exchange where users can deposit the base token of\nthe system and take long or short positions. Guaranteeing the stability of the\npegged tokens boils down to the problem of maintaining the peg of the virtual\nassets to real world assets, and the main mechanism used by Exeum is\ncontrolling the swap rate of assets. If the swap rate is fully controlled by\nthe system, arbitrageurs can be incentivized enough to restore a broken peg;\nExeum distributes statistical arbitrage trading software to decentralize this\ntype of market making activity. The last major component of the system is a\ncentral bank equivalent that determines the long term interest rate of the base\ntoken, pays interest on the deposit by inflating the supply if necessary, and\nremoves the need for stability fees on pegged tokens, improving their\nusability.\n To the best of our knowledge, Exeum is the first to propose a truly\ndecentralized method for developing a stablecoin that enables 1:1 value\nconversion between the base token and pegged assets, completely removing the\nmismatch between supply and demand. In this paper, we will also discuss its\napplications, such as improving staking based DApp token models, price stable\ngas fees, pegging to an index of DApp tokens, and performing cross-chain asset\ntransfer of legacy crypto assets.\n
In proof-of-stake based consortium blockchain networks, pre-selected miners compete to solve a crypto-puzzle with a successfully mining probability proportional to the amount of their stakes. When the puzzle is solved, the miners are encouraged to take part in mined block propagation for verification to win a transaction fee from the blockchain user. The mined block should be propagated over wired or wireless networks, and be verified as quickly as possible to decrease consensus propagation delay. In this letter, we study incentivizing the consensus propagation considering the tradeoff between the network delay of block propagation process and offered transaction fee from the blockchain user. A Stackelberg game is then formulated to jointly maximize utility of the blockchain user and individual profit of the miners. The blockchain user acting as the leader sets the transaction fee for block verification. The miners acting as the followers decide on the number of recruited verifiers over wired or wireless networks. We apply the backward induction to analyze the existence and uniqueness of the Stackelberg equilibrium. Performance evaluation validates the feasibility and efficiency of the proposed game model in consensus propagation.
Most cryptocurrency systems or systems based on blockchain technology are currently using the elliptic curves digital signature algorithm (ECDSA) on the secp256k1 curve, which is susceptible to backdoors implemented by the curve creator (secp256k1). The paper proposes a multiple elliptic curves digi-tal signature algorithm (MECDSA), which allows not only for setting the number of elliptic curves according to practical security requirements, but also for editing the parameters of each elliptic curve. The performance analy-sis proves that the scheme is secure and efficient, and can avoid any back-doors implemented by curve creators. We suggest that the systems based on blockchain should operate in two elliptic curves considering the contradic-tion between security and efficiency.
This thesis focuses on aspects related to the functioning of the gossip\nnetworks underlying three relatively popular cryptocurrencies: Ethereum, Nano\nand IOTA.\n We look at topics such as automatic discovery of peers when a new node joins\nthe network, bandwidth usage of a node, message passing protocols and storage\nschemas and optimizations for the shared ledger. We believe this is a topic\nthat is often overlooked in works about blockchains and cryptocurrencies.\nVulnerabilities and inefficiencies attain a higher significance than ones in a\nregular open source project because of the rather direct financial implications\nof these projects. Barring Bitcoin, a network that has been around for nearly\n10 years, no other project has substantial documentation for its operational\ndetails other than scattered and sparse pages in the source code repositories.\nAlmost all of the content described here has been extracted by studying the\nsource code of the reference implementations of these projects.\n We evaluate the use of Invertible Bloom Lookup Tables and the Graphene\nprotocol to decrease block propagation times and bandwidth usage of certain\nmessages. We perform realistic simulations that show significant improvements.\nWe provide a complete implementation of Graphene in Geth, Ethereum's main node\nsoftware and test this implementation against the main Ethereum blockchain.\n We also crawled the chosen cryptocurrency networks for publicly visible nodes\nand provide an Autonomous System-level breakdown of these nodes with the end\ngoal of estimating the ease of performing attacks such as BGP hijacks and their\nimpact.\n Code written for implementing Graphene in Geth, performing various\nsimulations and for other miscellaneous tasks has been uploaded to Github at\nhttps://github.com/sunfinite/masters-thesis.\n
We test the presence of regime changes in the GARCH volatility dynamics of Bitcoin log–returns using Markov–switching GARCH (MSGARCH) models. We also compare MSGARCH to traditional single–regime GARCH specifications in predicting one–day ahead Value–at–Risk (VaR). The Bayesian approach is used to estimate the model parameters and to compute the VaR forecasts. We find strong evidence of regime changes in the GARCH process and show that MSGARCH models outperform single–regime specifications when predicting the VaR.
We provide enhanced security against insider attacks in services that manage extremely sensitive data. One example is a #MeToo use case where sexual harassment complaints are reported but only revealed when another complaint is filed against the same perpetrator. Such a service places tremendous trust on service operators which our work aims to relieve. To this end we introduce a new autonomous data management concept which transfers responsibility for the sensitive data from administrators to secure and verifiable hardware. The main idea is to manage all data access via a cluster of autonomous computation agents running inside Intel SGX enclaves. These EConfidante agents share a secret data key which is unknown to any external entity, including the data service administrators, thus eliminating many opportunities for data exposure. In this paper we describe a detailed design of the EConfidante system, its flow and how it is managed and implemented. Our #MeToo design also uses an immutable distributed ledger which is built using components from a Blockchain framework. We implemented a proof of concept of our system for the #MeToo use case and analyze its security properties and implementation details.
Chinese power grid enterprises are in need for development of digital asset management system. The characteristics of decentralization, self-trust and self-confidence, pave a promising technical path for power grid digital assess management and Big Data applications. This article firstly introduces the state-of-the-art of power grid Big Data and digital asset management, and the related issues in power grid enterprises. The solution of blockchain based digital asset management technology and its implementation are presented in details, followed by a discussion of their future developmental directions.
Existing permissioned blockchain systems designate a fixed and explicit group of committee nodes to run a consensus protocol that confirms the same sequence of blocks among all nodes. Unfortunately, when such a permissioned blockchain runs in a large scale on the Internet, these explicit committee nodes can be easily turned down by denial-of-service (DoS) or network partition attacks. Although work proposes scalable BFT protocols that run on a larger number of committee nodes, their efficiency drops dramatically when only a small number of nodes are attacked. In this paper, our EGES protocol leverages Intel SGX to develop a new abstraction called "stealth committee", which effectively hides the committee nodes into a large pool of fake committee nodes. EGES selects a distinct group of stealth committee for each block and confirms the same sequence of blocks among all nodes with overwhelming probability. Evaluation on typical geo-distributed settings shows that: (1)EGES is the first permissioned blockchain's consensus protocol that can tolerate tough DoS and network partition attacks; and (2) EGES achieves comparable throughput and latency as existing permissioned blockchains' protocols
In recent years, the Darknet has become one of the most discussed topics in cyber security circles. Current academic studies and media reports tend to highlight how the anonymous nature of the Darknet is used to facilitate criminal activities. This paper reports on a recent research in four Darknet forums that reveals a different aspect of the Darknet. Drawing on our qualitative findings, we suggest that many users of the Darknet might not perceive it as intrinsically criminogenic, despite their acknowledgement of various kinds of criminal activity in this network. Further, our research participants emphasised on the achievement of constructive socio-political values through the use of the Darknet. This achievement is enabled by various characteristics that are rooted in the Darknet’s technological structure, such as anonymity, privacy, and the use of cryptocurrencies. These characteristics provide a wide range of opportunities for good as well as for evil.
As CKD progresses, the capacity of the kidneys to eliminate metabolic waste is gradually lost, resulting in the retention of a host of compounds. Many of these solutes affect biologic functions and are likely contributing to the uremic syndrome, affecting not only morbidity and mortality but also patient-centered outcomes (fatigue, pruritus, sleep disorders) and quality of life (1). Our knowledge on the nature and action of the uremic compounds is still expanding—a progress at least partly attributable to the acquisitions of metabolomic analysis, which allows the blinded search for previously unknown molecules (2). The intensive exploration of the role of the intestine in the generation of uremic toxins was set in motion only during the past decade (3). The chain of events at play generally begins with dietary protein degradation followed by the metabolic transformation (fermentation) of amino acids by the gut microbiota and their conjugation (mostly sulfatation and glucuronidation) in the intestinal wall or liver by phase 1 and phase 2 metabolizing enzymes. Conjugation is, essentially, intended to increase solubility and neutralize toxicity, but the latter effect may remain incomplete, as several end-products still exert toxicity (4). In the search for intestinally generated uremic solutes, some proof-of-concept metabolomic studies identified a number of discriminators by comparing plasma or urine from either germfree rodents with control animals (5) or human subjects with and without a colon (6). Several identified molecules appeared to be known protein-bound uremic toxins, such as indoxyl sulfate, p-cresyl sulfate, and phenyl sulfate. In this issue of the Clinical Journal of the American Society of Nephrology, Mair et al., in their study on patients on dialysis with and without a colon, used a slightly different approach than in their previous study (6), resulting in a considerable extension of our knowledge on uremic solutes of intestinal origin (7). A sophisticated analytic platform comparing urine of patients with normal kidney function with or without colon yielded 91 colon-derived molecules. This selection was then narrowed by comparing the plasma of controls with that of patients on maintenance hemodialysis, resulting in a definite list of 60 intestinally generated uremic solutes. By using a chemical reference library, Mair et al. (7) could then define the structure of 34 of these substances, among which 22 were classified as newly detected intestinally generated retention products. Many (but not all) of these solutes were protein bound and/or sulfates, glucuronides (as demonstrated by sample sulfatase treatment), or metabolites of phenyl acetic acid. For the majority of compounds of which it was possible to calculate kidney clearance, this parameter exceeded creatinine clearance. As the latter can be considered a proxy of GFR, this suggests substantial active kidney tubular secretion, and may cast some doubts on the value of GFR as an all-inclusive measure of kidney function. The question is how this considerable extension of knowledge can be applied for the better to improve the quality and sustainability of the treatment and life quality of patients with kidney failure. One point is certain: the idea that the uremic syndrome is a simple condition, resulting from the activity of one or a few retention solutes, is further away than ever. It seems tempting to embark upon a large experimental effort to unravel the toxicity of the newly detected solutes, but such an endeavor should not be underestimated. Next to the identification of the solutes per se, the uremic concentration needs to be determined which necessitates the availability of the pure compound (either purchased or synthesized) before the biochemical impact can be tested, preferably in several appropriate organ or cell systems (4). Such approach may be extremely time-consuming unless well designed, high-throughput systems can be applied. The number of solutes to be tested could, however, be reduced on the basis of data from large sample collections and big data analysis, taking into consideration hard outcomes as well as patient-centered end points. In addition, systems biology could be used to unravel interactions among metabolites, the most important pathways involved and the most important metabolites. Another option could be the selection of solutes with the most outspoken characteristics, e.g., the largest concentration gap between normal and hemodialysis or between those with and without a colon, or those solutes with the highest tubular secretion. Perhaps more importantly, the reported data may help guiding the development of novel therapeutic procedures. As the study by Mair et al. detected large clusters with common characteristics (sulfates and glucuronides; phenols, cresols, and indoles), these could be approached by specific sorption methods aimed at capturing these structures. If such methods can be developed, they could also help to offer proof of concept regarding whether removing those solutes improves outcomes. Another option suggested by this study is correction of the intestinal dysbiosis by modifying intestinal bacterial metabolism, for which several proof-of-concept studies are already available, applying different diets, probiotics, prebiotics, synbiotics, or antibiotics (8). However, it might be dangerous to jump to conclusions. When Mair et al. considered the urinary excretion ratio of patients without a colon versus controls per individual molecule, it almost always exceeded zero (7), suggesting extraintestinal sources. Likewise, even if one does not account for the five patients with an ileal pouch, which appears to preserve some intestinal microbial activity, more than 20 intestinally generated uremic solutes were found in the urine of some patients and seven were found in all patients without a colon. Also for other reasons, targeting the colon as an isolated effort may offer an insufficient response to the uremic problem. A recent classification on the basis of preset criteria summing up 24 uremic solutes with the most important biochemical and clinical impact (9) contained only four of the solutes retrieved in the analysis of Mair et al. (7) (indoxyl sulfate, p-cresyl sulfate, trimethylamine-N-oxide, and indole acetic acid). This does not exclude yet unproven toxicity of some of the newly retrieved solutes by this study (7), but does suggest that a large number of solutes with toxic potential may not be entirely of intestinal origin. Of note, the aggregated results of the study by Mair et al. (7) also point to the role of an axis comprising the intestine, liver, plasma protein binding, and tubular excretion, rather than one of the intestine alone. All these observations might translate into difficulties to sufficiently reduce concentration of the concerned solutes by applying intestinal methods only. Tackling the intestine may be one of the solutions, but it is not the only solution. Subsequently, research efforts should be continued and strengthened to develop also other alternative ways to enhance toxin removal, such as decreasing protein binding, sorption, preservation of kidney function, increasing tubular secretion, and applying various acquisitions at the intersection of kidney replacement therapy and regenerative medicine (bioartificial kidney) or regenerative medicine per se (stem cells, organoids, bioengineered kidneys). Stimulating research in these areas is an important task for the nephrological community and all those involved in health policy, as patients, their families, and health professionals are in need of innovations in a field that has stagnated for too long and has too high amounts of health expenditures in its current form. In this context, targeting the intestinal microbiome remains a cheap and noninvasive therapeutic option, with a potential outreach to a large number of patients. In spite of the impressive efforts to accomplish this analysis and the vast amount of information offered, the study by Mair et al. (7) unavoidably raises some questions and concerns. Regardless of the comforting double-check of the reliability of the data provided for the most familiar uremic solutes, mass spectrometric analysis as used here remains semiquantitative, which may be a source of error, especially for calculated values such as clearances, ratios, or free fractions. Also, the use of spot urines sometimes necessitating drastic dilution is a potential source of error. Some seemingly obvious colon-derived candidate molecules, such as indoxyl glucuronide, hippuric acid, or phenyl acetic acid, that were traced by other metabolomic studies, sometimes by the same group (6), were absent in this analysis, which makes one suspect that either analytical bias or individual differences in nutritional status, metabolism, or genetics, may affect the findings. Other potentially skewing factors may be the overwhelming majority of patients with CKD and those on hemodialysis suffering from diabetes versus none in the control and colectomy groups, or the presence in the colectomy group of patients on immunosuppressive agents, as both may modify the intestinal microbiome (10,11). In conclusion, this study contains convincing but not entirely unexpected evidence that colonic generation of uremic toxins concerns even more molecules than previously demonstrated. GFR is, in many cases, not representative of kidney clearance. The study also supports the concept of molecule families and the existence of a gut/liver/plasma protein binding/kidney tubular axis, the disruption of which by one or more therapeutic measures could bring down the concentration of those solutes. Research in these areas should be able to modify the current paradigm of kidney treatment to make it more sustainable. This includes the exploration of previously underexploited areas such as manipulation of intestinal function, and alternative extracorporeal removal strategies such as adsorption and regenerative medicine. Disclosures R.V. has received travel support and speakers fees from Nikisho and BBraun, and is a consultant for Debiotech, the Dutch Kidney Foundation, and Astra-Zeneca. G.G. reports no conflict.
Envisioned 5G use cases arise challenges around the realization of inter-domain relationships beyond traditional Border Gateway Protocol (BGP) peering, e.g. end-to-end service deployments tailored to specific business needs (a.k.a. slices). Blockchain technologies bring consensus among decentralized non-trusting counterparts as a shared ledger, offering potential approaches for multi-administrative domain networking seeking agile, transparent end-to-end sliceable Service Level Agreements (SLAs). This demo showcases an experimental prototype based on best of breed open source components (e.g., Ethereum, OVS, Neo4j, Ryu/OpenFlowv1.3, ARIA/TOSCA) illustrating blockchain Decentralized Application (DApp) functionalities for life cycle management of multi-administrative domain network services.
Purpose The purpose of this paper is to investigate meat traceability by outlining the different perspectives and opinions of meat supply chain stakeholders (SCSs); it also evaluates potential of acceptance of blockchain technology (BCT) as a viable transparency and traceability system (TTS). Design/methodology/approach A questionnaire survey of 141 consumers reveals their opinions about TTSs. In addition, semi-structured interviews with seven retail managers, four government officials and one blockchain service provider (Project Provenance Ltd) provide expert insights. Findings The results demonstrate that consumers are overwhelmed by the amount and complexity of certification labels. As a TTS, BCT implementation appears to have significant positive influences on consumers’ purchasing decisions, mediated by consumers’ quality perceptions. This study reveals the discordant perspectives of different stakeholders with regard to the importance of a BCT-based TTS. Originality/value This study investigates current TTSs and certification labels, and probes customer perception of a potential BCT-based solution for meat traceability. Changes to supply chains’ mentality and the active establishment of trust in BCT applications are needed. Firms should take both holistic and altruistic views to deal with the challenges of TTSs in the meat supply chain. The adoption of BCT, in combination with DNA coding, seems promising as a solution to many of the issues that currently plague TTSs.
This article surveys blockchain-based approaches for several security services. These services include authentication, confidentiality, privacy, and access control list (ACL), data and resource provenance, and integrity assurance. All these services are critical for the current distributed applications, especially due to the large amount of data being processed over the networks and the use of cloud computing. Authentication ensures that the user is who he/she claims to be. Confidentiality guarantees that data cannot be read by unauthorized users. Privacy provides the users the ability to control who can access their data. Provenance allows an efficient tracking of the data and resources along with their ownership and utilization over the network. Integrity helps in verifying that the data has not been modified or altered. These services are currently managed by centralized controllers, for example, a certificate authority. Therefore, the services are prone to attacks on the centralized controller. On the other hand, blockchain is a secured and distributed ledger that can help resolve many of the problems with centralization. The objectives of this paper are to give insights on the use of security services for current applications, to highlight the state of the art techniques that are currently used to provide these services, to describe their challenges, and to discuss how the blockchain technology can resolve these challenges. Further, several blockchain-based approaches providing such security services are compared thoroughly. Challenges associated with using blockchain-based security services are also discussed to spur further research in this area.
With the successful application of Bitcoin, the underlying blockchain technology has been attracted the attention by more and more scholars, financial institutions and commercial companies. Blockchain technology integrates some key technologies such as finance, cryptography, computer science, and game theory, and builds a distributed record system that is decentralized, mutually trusted, and tamper-proof. This paper demonstrates the basic principles and features of blockchain, then analyzes the key technologies and characteristics of blockchain technology including asymmetric encryption, P2P, consensus mechanisms, smart contracts. In the last part of the paper, the author summarizes the potential application scenarios to blockchain and focuses on applications of the blockchain technology in the power industry.
Новая технология и форма управления организацией, ставшие возможными благодаря развитию криптографии, - децентрализованная автономная организация (ДАО). В статье приведено описание архитектуры и эволюции ДАО в рамках теоретико-игровой модели. Проанализированы существующие организации, носящие статус ДАО, и описаны основные регулирующие их механизмы в терминах контрактов. В результате выделены основные проблемные области ДАО. Предложен ряд подходов, в перспективе частично или полностью решающих проблемы развития ДАО. The new technology as well as the new way to manage the organization are available due to the development of cryptography - decentralized autonomous organization (DAO). The article describes the architecture and evolution of DAO within the game-theoretic model. The existing organizations bearing the status of DAO are analyzed and the main regulatory mechanisms in terms of contracts are described. As a result, the main problem areas of DAO are identified. A number of approaches are proposed with these approaches partially or completely solving the problems of DAO development in the long run.
Blockchain has many benefits including decentralization, availability, persistency, consistency, anonymity, auditability and accountability, and it also covers a wide spectrum of applications ranging from cryptocurrency, financial services, reputation system, Internet of Things, sharing economy to public and social services. Not only may blockchain be regarded as a by-product of Bitcoin cryptocurrency systems, but also it is a type of distributed ledger technology through using a trustworthy, decentralized log of totally ordered transactions. By summarizing the literature of blockchain, it is found that more papers focus on engineering implementation and realization, while little work has been done on basic theory, for example, mathematical models (Markov processes, queueing theory and game models), performance analysis and optimization of blockchain systems. In this paper, we develop queueing theory of blockchain systems and provide system performance evaluation. To do this, we design a Markovian batch-service queueing system with two different service stages, while the two stages are suitable to well express the mining process in the miners pool and the building of a new blockchain. By using the matrix-geometric solution, we obtain a system stable condition and express three key performance measures: (a) The number of transactions in the queue, (b) the number of transactions in a block, and (c) the transaction-confirmation time. Finally, We use numerical examples to verify computability of our theoretical results. Although our queueing model is simple under exponential or Poisson assumptions, our analytic method will open a series of potentially promising research in queueing theory of blockchain systems.
Alfonso Panarello, Nachiket Tapas, Giovanni Merlino, Francesco Longo · 5 authors
The Internet of Things (IoT) refers to the interconnection of smart devices to collect data and make intelligent decisions. However, a lack of intrinsic security measures makes IoT vulnerable to privacy and security threats. With its "security by design," Blockchain (BC) can help in addressing major security requirements in IoT. BC capabilities like immutability, transparency, auditability, data encryption and operational resilience can help solve most architectural shortcomings of IoT. This article presents a comprehensive survey on BC and IoT integration. The objective of this paper is to analyze the current research trends on the usage of BC-related approaches and technologies in an IoT context. This paper presents the following novelties, with respect to related work: (i) it covers different application domains, organizing the available literature according to this categorization, (ii) it introduces two usage patterns, i.e., device manipulation and data management (open marketplace solution), and (iii) it reports on the development level of some of the presented solutions. We also analyze the main challenges faced by the research community in the smooth integration of BC and IoT, and point out the main open issues and future research directions. Last but not least, we also present a survey about novel uses of BC in the machine economy.
Changting Lin, Ning Ma, Xun Wang, Zhenguang Liu · 6 authors
Bitcoin blockchain faces the bitcoin scalability problem, for which bitcoin's blocks contain the transactions on the bitcoin network. The on-chain transaction processing capacity of the bitcoin network is limited by the average block creation time of 10 minutes and the block size limit. These jointly constrain the network's throughput. The transaction processing capacity maximum is estimated between 3.3 and 7 transactions per second (TPS). A Layer2 Network, named Lightning Network, is proposed and activated solutions to address this problem. LN operates on top of the bitcoin network as a cache to allow payments to be affected that are not immediately put on the blockchain. However, it also brings some drawbacks. In this paper, we observe a specific payment issue among current LN, which requires additional claims to blockchain and is time-consuming. We call the issue as shares issue. Therefore, we propose Rapido to explicitly address the shares issue. Furthermore, a new smart contract, D-HTLC, is equipped with Rapido as the payment protocol. We finally provide a proof of concept implementation and simulation for both Rapido and LN, in which Rapdio not only mitigates the shares issue but also mitigates the skewness issue thus is proved to be more applicable for various transactions than LN.
Sequences of random objects arise from many real applications, including high throughput omic data and functional imaging data. Those sequences are usually dependent, non-linear, or even Non-Euclidean, and an important problem is change-point detection in such dependent sequences in Banach spaces or metric spaces. The problem usually requires the accurate inference for not only whether changes might have occurred but also the locations of the changes when they did occur. To this end, we first introduce a Ball detection function and show that it reaches its maximum at the change-point if a sequence has only one change point. Furthermore, we propose a consistent estimator of Ball detection function based on which we develop a hierarchical algorithm to detect all possible change points. We prove that the estimated change-point locations are consistent. Our procedure can estimate the number of change-points and detect their locations without assuming any particular types of change-points as a change can occur in a sequence in different ways. Extensive simulation studies and analyses of two interesting real datasets wind direction and Bitcoin price demonstrate that our method has considerable advantages over existing competitors, especially when data are non-Euclidean or when there are distributional changes in the variance.
We present an example where a distributed coordinated protocol supported by a blockchain-enabled monetary mechanism leads to achieving optimal information theoretic degrees of freedom gains. The considered setting is that of a linear interference network, where cooperative transmission is allowed, but at no cost in terms of the overall backhaul load. In other words, the average number of messages assigned to a transmitter is one. We show that a simple monetary mechanism that consists only of one coin type can enable the achievability of the optimal centralized solution. The proposed greedy distributed algorithm relies on incentivizing the users to share their resources in one channel use, in return of credit they receive for maximizing their rate gains in future channel uses. This example is the first in its class and it opens the door for constructing a unified framework for blockchain-enabled monetary mechanisms for optimal interference management and spectrum sharing.
Miha E. Habič, Joel David Hamkins, Lukas Daniel Klausner, Jonathan L. Verner · 5 authors
Given a countable model of set theory, we study the structure of its generic multiverse, the collection of its forcing extensions and ground models, ordered by inclusion. Mostowski showed that any finite poset embeds into the generic multiverse while preserving the nonexistence of upper bounds. We obtain several improvements of his result, using what we call the blockchain construction to build generic objects with varying degrees of mutual genericity. The method accommodates certain infinite posets, and we can realize these embeddings via a wide variety of forcing notions, while providing control over lower bounds as well. We also give a generalization to class forcing in the context of second-order set theory, and exhibit some further structure in the generic multiverse, such as the existence of exact pairs.