We propose DIPS (Difficulty-based Incentives for Problem Solving), a simple modification of the Bitcoin proof-of-work algorithm that rewards blockchain miners for solving optimization problems of scientific interest. The result is a blockchain which redirects some of the computational resources invested in hash-based mining towards scientific computation, effectively reducing the amount of energy ‘wasted’ on mining. DIPS builds the solving incentive directly in the proof-of-work by providing a reduction in block hashing difficulty when optimization improvements are found. A key advantage of this scheme is that decentralization is not greatly compromised while maintaining a simple blockchain design. We study two incentivization schemes and provide simulation results showing that DIPS is able to reduce the amount of hash-power used in the network while generating solutions to optimization problems.
{"title":"Difficulty Scaling in Proof of Work for Decentralized Problem Solving","authors":"P. Philippopoulos, A. Ricottone, Carlos G. Oliver","doi":"10.5195/ledger.2020.194","DOIUrl":"https://doi.org/10.5195/ledger.2020.194","url":null,"abstract":"We propose DIPS (Difficulty-based Incentives for Problem Solving), a simple modification of the Bitcoin proof-of-work algorithm that rewards blockchain miners for solving optimization problems of scientific interest. The result is a blockchain which redirects some of the computational resources invested in hash-based mining towards scientific computation, effectively reducing the amount of energy ‘wasted’ on mining. DIPS builds the solving incentive directly in the proof-of-work by providing a reduction in block hashing difficulty when optimization improvements are found. A key advantage of this scheme is that decentralization is not greatly compromised while maintaining a simple blockchain design. We study two incentivization schemes and provide simulation results showing that DIPS is able to reduce the amount of hash-power used in the network while generating solutions to optimization problems.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":"5 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48434406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using Bitcoin trading data in Venezuelan bolivars from the LocalBitcoins peer-to-peer market place and using the theory of Purchasing Power Parity (PPP), Bitcoin, as a single universal asset, is substituted for the ‘basket of goods’ normally used in the PPP, allowing the estimation of the relationship between the Venezuelan bolivar and the United States dollar. In this analysis Bitcoin is used as a tool to enable the calculation of the bolivars to dollars unofficial exchange rate and consequently the implied inflation rate. Using Bitcoin’s publicly available prices in this way enables a government’s economic mismanagement to be identified more quickly than the typical approach of measuring changes in the Consumer Price Index. Venezuela is currently in crisis, which this approach identifies as a problem as far back as 2014, as official and unofficial exchange rates diverge and inflation rates increase yearly reaching an unbelievable 70,000% in 2018 alone.
{"title":"Bitcoin and Venezuela's Unofficial Exchange Rate","authors":"Jackie Johnson","doi":"10.5195/LEDGER.2019.170","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.170","url":null,"abstract":"Using Bitcoin trading data in Venezuelan bolivars from the LocalBitcoins peer-to-peer market place and using the theory of Purchasing Power Parity (PPP), Bitcoin, as a single universal asset, is substituted for the ‘basket of goods’ normally used in the PPP, allowing the estimation of the relationship between the Venezuelan bolivar and the United States dollar. In this analysis Bitcoin is used as a tool to enable the calculation of the bolivars to dollars unofficial exchange rate and consequently the implied inflation rate. Using Bitcoin’s publicly available prices in this way enables a government’s economic mismanagement to be identified more quickly than the typical approach of measuring changes in the Consumer Price Index. Venezuela is currently in crisis, which this approach identifies as a problem as far back as 2014, as official and unofficial exchange rates diverge and inflation rates increase yearly reaching an unbelievable 70,000% in 2018 alone.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43628149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Confirmation of Bitcoin transactions is executed in blocks, which are then stored in the Blockchain. As compared to the number of transactions in the mempool, the set of transactions which are verified but not yet confirmed, available space for inclusion in a block is typically limited. For this reason, successful miners can only process a subset of such transactions, and users compete with each other to enter the next block by offering confirmation fees. Assuming that successful miners pursue revenue maximization, they will include in the block those mempool transactions that maximize earnings from related fees. In the paper we model transaction fees as a Nash Equilibrium outcome of an auction game with complete information. In the game the successful miner acts as an auctioneer selling block space, and users bid for shares of such space to confirm their transactions. Moreover, based on expected fees we also discuss what the optimal, revenue maximizing, block size limit should be for the successful miner. Consistently with the intuition, the optimal block size limit resolves the trade-off between including additional transactions (which possibly lower the unit fees collected) and keeping the block capacity limited (with, however, higher unit fees).
{"title":"Transaction Fees, Block Size Limit, and Auctions in Bitcoin","authors":"N. Dimitri","doi":"10.5195/LEDGER.2019.145","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.145","url":null,"abstract":"Confirmation of Bitcoin transactions is executed in blocks, which are then stored in the Blockchain. As compared to the number of transactions in the mempool, the set of transactions which are verified but not yet confirmed, available space for inclusion in a block is typically limited. For this reason, successful miners can only process a subset of such transactions, and users compete with each other to enter the next block by offering confirmation fees. Assuming that successful miners pursue revenue maximization, they will include in the block those mempool transactions that maximize earnings from related fees. In the paper we model transaction fees as a Nash Equilibrium outcome of an auction game with complete information. In the game the successful miner acts as an auctioneer selling block space, and users bid for shares of such space to confirm their transactions. Moreover, based on expected fees we also discuss what the optimal, revenue maximizing, block size limit should be for the successful miner. Consistently with the intuition, the optimal block size limit resolves the trade-off between including additional transactions (which possibly lower the unit fees collected) and keeping the block capacity limited (with, however, higher unit fees).","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45912683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we aim to incorporate the expertise of anonymous curators into a token-curated registry (TCR), a decentralized recommender system for collecting a list of high-quality content. This registry is important, because previous studies on TCRs have not specifically focused on technical content, such as academic papers and patents, whose effective curation requires expertise in relevant fields. To measure expertise, curation in our model focuses on both the content and its citation relationships, for which curator assignment uses the Personalized PageRank (PPR) algorithm while reward computation uses a multi-task peer-prediction mechanism. Our proposed CitedTCR bridges the literature on network-based and token-based recommender systems and contributes to the autonomous development of an evolving citation graph for high-quality content. Moreover, we experimentally confirm the incentive for registration and curation in CitedTCR using the simplification of a one-to-one correspondence between users and content (nodes).
{"title":"Token-Curated Registry with Citation Graph","authors":"Kensuke Ito, Hideyuki Tanaka","doi":"10.5195/ledger.2019.182","DOIUrl":"https://doi.org/10.5195/ledger.2019.182","url":null,"abstract":"In this study, we aim to incorporate the expertise of anonymous curators into a token-curated registry (TCR), a decentralized recommender system for collecting a list of high-quality content. This registry is important, because previous studies on TCRs have not specifically focused on technical content, such as academic papers and patents, whose effective curation requires expertise in relevant fields. To measure expertise, curation in our model focuses on both the content and its citation relationships, for which curator assignment uses the Personalized PageRank (PPR) algorithm while reward computation uses a multi-task peer-prediction mechanism. Our proposed CitedTCR bridges the literature on network-based and token-based recommender systems and contributes to the autonomous development of an evolving citation graph for high-quality content. Moreover, we experimentally confirm the incentive for registration and curation in CitedTCR using the simplification of a one-to-one correspondence between users and content (nodes).","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43852625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper I discuss how blockchains potentially could affect the way credit risk is modeled, and how the improved trust and timing associated with blockchain-enabled real-time accounting could improve default prediction. To demonstrate the (quite substantial) effect the change would have on well-known credit risk measures, a simple case-study compares Z-scores and Merton distances to default computed using typical accounting data of today to the same risk measures computed under a hypothetical future blockchain regime.
{"title":"Blockchains, Real-time Accounting, and the Future of Credit Risk Modeling","authors":"H. Byström","doi":"10.5195/LEDGER.2019.100","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.100","url":null,"abstract":"In this paper I discuss how blockchains potentially could affect the way credit risk is modeled, and how the improved trust and timing associated with blockchain-enabled real-time accounting could improve default prediction. To demonstrate the (quite substantial) effect the change would have on well-known credit risk measures, a simple case-study compares Z-scores and Merton distances to default computed using typical accounting data of today to the same risk measures computed under a hypothetical future blockchain regime.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43010043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Social networking sites have given users unprecedented opportunities for the generation and dissemination of content. A variety of social networking sites exist for different purposes, to afford users a range of anonymous and non-anonymous options for self-expression, and the ability to be a part of a virtual community. These “affordances” enable users to create and share content; however, the ability to partially or wholly detach user identity from the content has resulted in unique challenges for content access and content attribution. This paper proposes a framework for secure, trustworthy social networking that also creates value for user-generated content by using a blockchain-enhanced framework for social networking. This work explains the application of such a framework for collocated spaces of robots and IoT devices and identifies key challenges that result as a consequence of merging social networking sites and blockchain technology.
{"title":"A Blockchain Enhanced Framework for Social Networking","authors":"R. Murimi","doi":"10.5195/LEDGER.2019.178","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.178","url":null,"abstract":"Social networking sites have given users unprecedented opportunities for the generation and dissemination of content. A variety of social networking sites exist for different purposes, to afford users a range of anonymous and non-anonymous options for self-expression, and the ability to be a part of a virtual community. These “affordances” enable users to create and share content; however, the ability to partially or wholly detach user identity from the content has resulted in unique challenges for content access and content attribution. This paper proposes a framework for secure, trustworthy social networking that also creates value for user-generated content by using a blockchain-enhanced framework for social networking. This work explains the application of such a framework for collocated spaces of robots and IoT devices and identifies key challenges that result as a consequence of merging social networking sites and blockchain technology.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45986961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jason A. Tran, G. Ramachandran, Palash M Shah, C. Danilov, Rodolfo A. Santiago, B. Krishnamachari
Blockchain technology has the potential to disrupt applications beyond cryptocurrencies. This work applies the concepts of blockchain technology to swarm robotics applications. Swarm robots typically operate in a distributed fashion, wherein the collaboration and coordination between the robots are essential to accomplishing the application goals. However, robot swarms may experience network partitions either due to navigational and communication challenges or in order to perform certain tasks efficiently. We propose a novel protocol, SwarmDAG, that enables the maintenance of a distributed ledger based on the concept of extended virtual synchrony while managing and tolerating network partitions.
{"title":"SwarmDAG: A Partition Tolerant Distributed Ledger Protocol for Swarm Robotics","authors":"Jason A. Tran, G. Ramachandran, Palash M Shah, C. Danilov, Rodolfo A. Santiago, B. Krishnamachari","doi":"10.5195/LEDGER.2019.174","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.174","url":null,"abstract":"Blockchain technology has the potential to disrupt applications beyond cryptocurrencies. This work applies the concepts of blockchain technology to swarm robotics applications. Swarm robots typically operate in a distributed fashion, wherein the collaboration and coordination between the robots are essential to accomplishing the application goals. However, robot swarms may experience network partitions either due to navigational and communication challenges or in order to perform certain tasks efficiently. We propose a novel protocol, SwarmDAG, that enables the maintenance of a distributed ledger based on the concept of extended virtual synchrony while managing and tolerating network partitions.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43708344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Kapitonov, Sergey Lonshakov, Ivan Berman, Eduardo Castelló Ferrer, F. Bonsignorio, Vitaly Bulatov, A. Svistov
This article describes different methods of organizing robotic services for smart cities using secure encrypted decentralized technologies and market mechanisms—as opposed to models based on centralized solutions based (or not) on using cloud services and stripping citizens of the control of their own data. The basis of the proposed methods is the Ethereum decentralized computer with the mechanism of smart contracts. In this work, special attention is paid to the integration of technical and economic information into one network of transactions, which allows creating a unified way of interaction between robots—the robot economy. Three possible scenarios of robotic services for smart cities based on the economy of robots are presented: unmanned aerial vehicles (UAVs), environmental monitoring, and smart factories. In order to demonstrate the feasibility of the proposed scenarios, three experiments are presented and discussed. Our work shows that the Ethereum network can provide, through smart contracts and their ability to activate programs to interact with the physical world, an effective and practical way to manage robot services for smart cities.
{"title":"Robotic Services for New Paradigm Smart Cities Based on Decentralized Technologies","authors":"A. Kapitonov, Sergey Lonshakov, Ivan Berman, Eduardo Castelló Ferrer, F. Bonsignorio, Vitaly Bulatov, A. Svistov","doi":"10.5195/LEDGER.2019.177","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.177","url":null,"abstract":"This article describes different methods of organizing robotic services for smart cities using secure encrypted decentralized technologies and market mechanisms—as opposed to models based on centralized solutions based (or not) on using cloud services and stripping citizens of the control of their own data. The basis of the proposed methods is the Ethereum decentralized computer with the mechanism of smart contracts. In this work, special attention is paid to the integration of technical and economic information into one network of transactions, which allows creating a unified way of interaction between robots—the robot economy. Three possible scenarios of robotic services for smart cities based on the economy of robots are presented: unmanned aerial vehicles (UAVs), environmental monitoring, and smart factories. In order to demonstrate the feasibility of the proposed scenarios, three experiments are presented and discussed. Our work shows that the Ethereum network can provide, through smart contracts and their ability to activate programs to interact with the physical world, an effective and practical way to manage robot services for smart cities.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41886874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aswin Karthik Ramachandran Venkatapathy, M. T. Hompel
A context broker is a reliable message-relaying service used to connect devices by integrating all device protocols and communication methods, and reliably transporting messages while isolating data from other application service layers and networking complexities. A highly scalable decentralized context broker stack is composed of three layers—starting with a peer-to-peer network connecting a byzantine fault-tolerant (i.e., blockchain-based) consensus protocol—and it manages the communication using a web-socket streaming protocol as interface to other applications. This paper presents such a concept for a decentralized context broker stack for intercommunication between heterogeneous materials handling systems, and deploys the stack as proof-of-concept using ROS-based robots in a logistics scenario.
{"title":"A Decentralized Context Broker Using Byzantine Fault Tolerant Consensus","authors":"Aswin Karthik Ramachandran Venkatapathy, M. T. Hompel","doi":"10.5195/LEDGER.2019.173","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.173","url":null,"abstract":"A context broker is a reliable message-relaying service used to connect devices by integrating all device protocols and communication methods, and reliably transporting messages while isolating data from other application service layers and networking complexities. A highly scalable decentralized context broker stack is composed of three layers—starting with a peer-to-peer network connecting a byzantine fault-tolerant (i.e., blockchain-based) consensus protocol—and it manages the communication using a web-socket streaming protocol as interface to other applications. This paper presents such a concept for a decentralized context broker stack for intercommunication between heterogeneous materials handling systems, and deploys the stack as proof-of-concept using ROS-based robots in a logistics scenario.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41810725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Robots are important equipment in the modern day factory environment. To maintain and improve factory productivity, ledgers containing robotic actions may be used to identify possible bottleneck points in an assembly line or to serve as a record of in unintentional behaviours, be it of a malicious nature or not. In this paper we present Robotchain, a possible solution using blockchain technology, that prevents unwanted changes in a robotic action ledger and provides a way to use the said ledger in order to aid in production efficiency or other management requirements. This paper also presents an initial experimental study of the Tezos blockchain in order to understand the challenges related to using its advanced blockchain technology for the Robotchain implementation.
{"title":"Robotchain: Using Tezos Technology for Robot Event Management","authors":"Miguel Fernandes, Luís A. Alexandre","doi":"10.5195/LEDGER.2019.175","DOIUrl":"https://doi.org/10.5195/LEDGER.2019.175","url":null,"abstract":"Robots are important equipment in the modern day factory environment. To maintain and improve factory productivity, ledgers containing robotic actions may be used to identify possible bottleneck points in an assembly line or to serve as a record of in unintentional behaviours, be it of a malicious nature or not. In this paper we present Robotchain, a possible solution using blockchain technology, that prevents unwanted changes in a robotic action ledger and provides a way to use the said ledger in order to aid in production efficiency or other management requirements. This paper also presents an initial experimental study of the Tezos blockchain in order to understand the challenges related to using its advanced blockchain technology for the Robotchain implementation.","PeriodicalId":36240,"journal":{"name":"Ledger","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2019-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48334521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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