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Este artigo apresenta a plataforma NeoCompiler Eco, com foco em desenvolvimento e experimentação para contratos inteligentes, bem como sistemas de consenso para blockchain. O NeoCompiler é um projeto livre iniciado em 2017, já estabelecido online (em produção) e com usuários em escala global. Ele consiste em diversos módulos, dentre eles: suporte a compilação de contratos inteligentes Turing-completos escritos em linguagens populares para o bytecode da blockchain; testes e implantação de contratos em uma rede pública compartilhada temporária e de alcance global; ferramentas didáticas auxiliares para conversões de tipos e blockchain explorer interno para visualização de transações e blocos; chat interativo para dúvidas entre participantes (globais); interação e visualização gráfica do processo de consenso. Dentre as realizações da plataforma, ressaltamos: apoio a disciplinas no tópico de blockchain, realização de hackathons no Brasil, América Latina e mundiais; apoio à rede experimental "Nosso DLT'' e desenvolvimento de algoritmos de consenso inovadores, como o dBFT 2.0 lançado em 2019.
Igor M. Coelho; Vitor N. Coelho. NeoCompiler Eco: experimentação de consenso em blockchain e contratos inteligentes. Anais do VI Workshop do Testbed FIBRE (WFIBRE 2021) 2021, 57 -67.
AMA StyleIgor M. Coelho, Vitor N. Coelho. NeoCompiler Eco: experimentação de consenso em blockchain e contratos inteligentes. Anais do VI Workshop do Testbed FIBRE (WFIBRE 2021). 2021; ():57-67.
Chicago/Turabian StyleIgor M. Coelho; Vitor N. Coelho. 2021. "NeoCompiler Eco: experimentação de consenso em blockchain e contratos inteligentes." Anais do VI Workshop do Testbed FIBRE (WFIBRE 2021) , no. : 57-67.
In critical systems, failures or errors can cause catastrophes, such as deaths or considerably losses of money. Model checking provides an automated way to prove the correctness of programs' requirements. It is a convenient technique to use in systems that need reliability. Propositional Dynamic Logic (PDL) is a formal system designed to reason about programs. This work presents a compiler implementation from a subset of the C language and also for the Smacco model, both to the PDL language, and after that to the language of the nuXmv model checker. This implementation is linked with a Blockchain model generation system to model and reason about smart contracts.
Allan Patrick; Igor Machado Coelho; Bruno Lopes. Automatic program verification in Dynamic Logic with applications to smart contracts. Anais do II Workshop Brasileiro de Lógica (WBL 2021) 2021, 1 -8.
AMA StyleAllan Patrick, Igor Machado Coelho, Bruno Lopes. Automatic program verification in Dynamic Logic with applications to smart contracts. Anais do II Workshop Brasileiro de Lógica (WBL 2021). 2021; ():1-8.
Chicago/Turabian StyleAllan Patrick; Igor Machado Coelho; Bruno Lopes. 2021. "Automatic program verification in Dynamic Logic with applications to smart contracts." Anais do II Workshop Brasileiro de Lógica (WBL 2021) , no. : 1-8.
This paper introduces state-of-the-art possibilities for using smart contracts capabilities for governance. Assisted by blockchain, the use of these tools can provide a transition that society currently needs due the huge amount of information that reaches citizens. The core mechanism of this study lies within the scope of smart accounts and digital identities. These topics enclose smart cities trends that seek to increase citizens’ participation in the social decision making process, in a transparent way that is usually managed throughout decentralized systems. We define a set of available features that can automatically guide the flow of resources, after the conclusions of voting processes also conducted on trusted environments of distributed ledgers. By presenting innovative ideas and didactically describing the possibilities, we aim to promote awareness of blockchain capabilities among readers, students, decisions makers and, mainly, the younger generation.
Vitor Coelho; Thays Oliveira; Wellington Tavares; Igor Coelho. Smart Accounts for Decentralized Governance on Smart Cities. Smart Cities 2021, 4, 881 -893.
AMA StyleVitor Coelho, Thays Oliveira, Wellington Tavares, Igor Coelho. Smart Accounts for Decentralized Governance on Smart Cities. Smart Cities. 2021; 4 (2):881-893.
Chicago/Turabian StyleVitor Coelho; Thays Oliveira; Wellington Tavares; Igor Coelho. 2021. "Smart Accounts for Decentralized Governance on Smart Cities." Smart Cities 4, no. 2: 881-893.
Heuristics denote a powerful concept, covering a wide range of computational, economic, and psychological sciences, as the ability to handle challenging problems with minimal resources. From a computational perspective, heuristics are commonly used in decision making - when vast amounts of information are available in complex environments - or even when dealing with intractable problems. Through shortcuts and tricks, they can produce acceptable solutions even with few resources compared to exhaustive approaches. Although found on many practical applications, their rich interdisciplinary history is not commonly explored in literature. This paper presents a recent and comprehensive literature review on the topic of heuristics. We present historical data that emphasizing the growth of this concept in several research fields, since the 1950s, and the authors' perspective on future directions. This history is told with a timeline as background, highlighting from the bounded rationality to computational intractability.
Gustavo Silva Semaan; Jose Andre De Moura Brito; Igor Machado Coelho; Edelberto Franco Silva; Augusto Cesar Fadel; Luiz Satoru Ochi; Nelson Maculan. A Brief History of Heuristics: from Bounded Rationality to Intractability. IEEE Latin America Transactions 2020, 18, 1975 -1986.
AMA StyleGustavo Silva Semaan, Jose Andre De Moura Brito, Igor Machado Coelho, Edelberto Franco Silva, Augusto Cesar Fadel, Luiz Satoru Ochi, Nelson Maculan. A Brief History of Heuristics: from Bounded Rationality to Intractability. IEEE Latin America Transactions. 2020; 18 (11):1975-1986.
Chicago/Turabian StyleGustavo Silva Semaan; Jose Andre De Moura Brito; Igor Machado Coelho; Edelberto Franco Silva; Augusto Cesar Fadel; Luiz Satoru Ochi; Nelson Maculan. 2020. "A Brief History of Heuristics: from Bounded Rationality to Intractability." IEEE Latin America Transactions 18, no. 11: 1975-1986.
Mixed-integer mathematical programming has been widely used to model and solve challenging optimization problems. One interesting feature of this technique is the ability to prove the optimality of the achieved solution, for many practical scenarios where a linear programming model can be devised. This paper explores its use to model very strong Byzantine adversaries, in the context of distributed consensus systems. In particular, we apply the proposed technique to find challenging adversarial conditions on a state-of-the-art blockchain consensus: the Neo dBFT. Neo Blockchain has been using the dBFT algorithm since its foundation, but, due to the complexity of the algorithm, it is challenging to devise definitive algebraic proofs that guarantee safety/liveness of the system (and adjust for every change proposed by the community). Core developers have to manually devise and explore possible adversarial attacks scenarios as an exhaustive task. The proposed multi-objective model is intended to assist the search of possible faulty scenario, which includes three objective functions that can be combined as a maximization problem for testing one-block finality or a minimization problem for ensuring liveness. Automated graphics help developers to visually observe attack conditions and to quickly find a solution. This paper proposes an exact adversarial model that explores current limits for practical blockchain consensus applications such as dBFT, with ideas that can also be extended to other decentralized ledger technologies.
Vitor Nazário Coelho; Rodolfo Pereira Araújo; Haroldo Gambini Santos; Wang Yong Qiang; Igor Machado Coelho. A MILP Model for a Byzantine Fault Tolerant Blockchain Consensus. Future Internet 2020, 12, 185 .
AMA StyleVitor Nazário Coelho, Rodolfo Pereira Araújo, Haroldo Gambini Santos, Wang Yong Qiang, Igor Machado Coelho. A MILP Model for a Byzantine Fault Tolerant Blockchain Consensus. Future Internet. 2020; 12 (11):185.
Chicago/Turabian StyleVitor Nazário Coelho; Rodolfo Pereira Araújo; Haroldo Gambini Santos; Wang Yong Qiang; Igor Machado Coelho. 2020. "A MILP Model for a Byzantine Fault Tolerant Blockchain Consensus." Future Internet 12, no. 11: 185.
Consensus mechanisms are a core feature for handling negotiation and agreements. Blockchain technology has seen the introduction of different sorts of consensus mechanism, ranging from tasks of heavy computation to the subtle mathematical proofs of Byzantine agreements. This paper presents the pioneer Delegated Byzantine Fault Tolerance (dBFT) protocol of Neo Blockchain, which was inspired by the Practical Byzantine Fault Tolerance (PBFT). Besides introducing its history, this study describes proofs and didactic examples, as well as novel design and extensions for Neo dBFT with multiple block proposals. Finally, we discuss challenges when dealing with strong Byzantine adversaries, and propose solutions inspired on PBFT for current weak-synchrony problems and increasing system robustness against attacks.
Igor M. Coelho; Vitor N. Coelho; Rodolfo P. Araujo; Wang Yong Qiang; Brett D. Rhodes. Challenges of PBFT-Inspired Consensus for Blockchain and Enhancements over Neo dBFT. Future Internet 2020, 12, 129 .
AMA StyleIgor M. Coelho, Vitor N. Coelho, Rodolfo P. Araujo, Wang Yong Qiang, Brett D. Rhodes. Challenges of PBFT-Inspired Consensus for Blockchain and Enhancements over Neo dBFT. Future Internet. 2020; 12 (8):129.
Chicago/Turabian StyleIgor M. Coelho; Vitor N. Coelho; Rodolfo P. Araujo; Wang Yong Qiang; Brett D. Rhodes. 2020. "Challenges of PBFT-Inspired Consensus for Blockchain and Enhancements over Neo dBFT." Future Internet 12, no. 8: 129.
Cities are constantly transforming and, consequently, attracting efforts from researchers and opportunities to the industry. New transportation systems are being built in order to meet sustainability and efficiency criteria, as well as being adapted to the current possibilities. Moreover, citizens are becoming aware about the power and possibilities provided by the current generation of autonomous devices. In this sense, this paper presents and discusses state-of-the-art transportation technologies and systems, highlighting the advances that the concepts of Internet of Things and Value are providing. Decentralized technologies, such as blockchain, are been extensively investigated by the industry, however, its widespread adoption in cities is still desirable. Aligned with operations research opportunities, this paper identifies different points in which cities’ services could move to. This also study comments about different combinatorial optimization problems that might be useful and important for an efficient evolution of our cities. By considering different perspectives, didactic examples are presented with a main focus on motivating decision makers to balance citizens, investors and industry goals and wishes.
Thays A. Oliveira; Yuri B. Gabrich; Helena Ramalhinho; Miquel Oliver; Miri W. Cohen; Luiz S. Ochi; Serigne Gueye; Fábio Protti; Alysson A. Pinto; Diógenes V. M. Ferreira; Igor M. Coelho; Vitor N. Coelho. Mobility, Citizens, Innovation and Technology in Digital and Smart Cities. Future Internet 2020, 12, 22 .
AMA StyleThays A. Oliveira, Yuri B. Gabrich, Helena Ramalhinho, Miquel Oliver, Miri W. Cohen, Luiz S. Ochi, Serigne Gueye, Fábio Protti, Alysson A. Pinto, Diógenes V. M. Ferreira, Igor M. Coelho, Vitor N. Coelho. Mobility, Citizens, Innovation and Technology in Digital and Smart Cities. Future Internet. 2020; 12 (2):22.
Chicago/Turabian StyleThays A. Oliveira; Yuri B. Gabrich; Helena Ramalhinho; Miquel Oliver; Miri W. Cohen; Luiz S. Ochi; Serigne Gueye; Fábio Protti; Alysson A. Pinto; Diógenes V. M. Ferreira; Igor M. Coelho; Vitor N. Coelho. 2020. "Mobility, Citizens, Innovation and Technology in Digital and Smart Cities." Future Internet 12, no. 2: 22.
Eyder Rios; Luiz Satoru Ochi; Cristina Boeres; Vitor N. Coelho; Igor M. Coelho; Ricardo Farias. Exploring parallel multi-GPU local search strategies in a metaheuristic framework. Journal of Parallel and Distributed Computing 2018, 111, 39 -55.
AMA StyleEyder Rios, Luiz Satoru Ochi, Cristina Boeres, Vitor N. Coelho, Igor M. Coelho, Ricardo Farias. Exploring parallel multi-GPU local search strategies in a metaheuristic framework. Journal of Parallel and Distributed Computing. 2018; 111 ():39-55.
Chicago/Turabian StyleEyder Rios; Luiz Satoru Ochi; Cristina Boeres; Vitor N. Coelho; Igor M. Coelho; Ricardo Farias. 2018. "Exploring parallel multi-GPU local search strategies in a metaheuristic framework." Journal of Parallel and Distributed Computing 111, no. : 39-55.
V.N. Coelho; I.M. Coelho; Marcone Souza; Frederico Guimarães; Eduardo Luz; A.C. Barbosa; G.G. Netto; R.C. Costa; A.A. Pinto; A. De P. Figueiredo; M.E.V. Elias; D.C.O.G. Filho; T.A. Oliveira. EEG time series learning and classification using a hybrid forecasting model calibrated with GVNS. Electronic Notes in Discrete Mathematics 2017, 58, 79 -86.
AMA StyleV.N. Coelho, I.M. Coelho, Marcone Souza, Frederico Guimarães, Eduardo Luz, A.C. Barbosa, G.G. Netto, R.C. Costa, A.A. Pinto, A. De P. Figueiredo, M.E.V. Elias, D.C.O.G. Filho, T.A. Oliveira. EEG time series learning and classification using a hybrid forecasting model calibrated with GVNS. Electronic Notes in Discrete Mathematics. 2017; 58 ():79-86.
Chicago/Turabian StyleV.N. Coelho; I.M. Coelho; Marcone Souza; Frederico Guimarães; Eduardo Luz; A.C. Barbosa; G.G. Netto; R.C. Costa; A.A. Pinto; A. De P. Figueiredo; M.E.V. Elias; D.C.O.G. Filho; T.A. Oliveira. 2017. "EEG time series learning and classification using a hybrid forecasting model calibrated with GVNS." Electronic Notes in Discrete Mathematics 58, no. : 79-86.
Environmental issues have become increasingly important to industry and business in recent days. This trend forces the companies to take responsibility for product recovery, and proper recycling and disposal, moving towards the design of sustainable green supply chains. This paper addresses the backward stream in transportation of products, by means of reverse logistics applied to vehicle routing. This problem, called single vehicle routing problem with deliveries and selective pickups, consists in finding a route that starts from the depot and visits all delivery customers. Some pickup customers may also be visited, since the capacity of the truck is not exceeded, and there is also a revenue associated with each pickup. We develop an algorithm inspired on the variable neighbourhood search metaheuristic that explores the power of modern graphics processing unit (GPU) to provide routes in reasonable computational time. The proposed algorithm called four-neighbourhood variable neighbourhood search (FN-VNS) includes a novel high-quality initial solution generator, a CPU–GPU integrated perturbation strategy and four different neighbourhood searches implemented purely in GPU for the local search phase. Our experimental results show that FN-VNS is able to improve the quality of the solution for 51 instances out of 68 instances taken from the literature. Finally, we obtained speedups up to 14.49 times, varying from 17.42 up to 76.84 for each local search, measured over a set of new large-size instances.
I.M. Coelho; P.L.A. Munhoz; L.S. Ochi; M.J.F. Souza; C. Bentes; R. Farias. An integrated CPU–GPU heuristic inspired on variable neighbourhood search for the single vehicle routing problem with deliveries and selective pickups. International Journal of Production Research 2015, 54, 945 -962.
AMA StyleI.M. Coelho, P.L.A. Munhoz, L.S. Ochi, M.J.F. Souza, C. Bentes, R. Farias. An integrated CPU–GPU heuristic inspired on variable neighbourhood search for the single vehicle routing problem with deliveries and selective pickups. International Journal of Production Research. 2015; 54 (4):945-962.
Chicago/Turabian StyleI.M. Coelho; P.L.A. Munhoz; L.S. Ochi; M.J.F. Souza; C. Bentes; R. Farias. 2015. "An integrated CPU–GPU heuristic inspired on variable neighbourhood search for the single vehicle routing problem with deliveries and selective pickups." International Journal of Production Research 54, no. 4: 945-962.
T.A. Oliveira; V.N. Coelho; Marcone Souza; D.L.T. Boava; F. Boava; I.M. Coelho. A hybrid variable neighborhood search algorithm for targeted offers in direct marketing. Electronic Notes in Discrete Mathematics 2015, 47, 205 -212.
AMA StyleT.A. Oliveira, V.N. Coelho, Marcone Souza, D.L.T. Boava, F. Boava, I.M. Coelho. A hybrid variable neighborhood search algorithm for targeted offers in direct marketing. Electronic Notes in Discrete Mathematics. 2015; 47 ():205-212.
Chicago/Turabian StyleT.A. Oliveira; V.N. Coelho; Marcone Souza; D.L.T. Boava; F. Boava; I.M. Coelho. 2015. "A hybrid variable neighborhood search algorithm for targeted offers in direct marketing." Electronic Notes in Discrete Mathematics 47, no. : 205-212.
This work treats the single machine scheduling problem in which the setup time depends on the sequence and the job family. The objective is to minimize the makespan and the total weighted tardiness. In order to solve the problem two multi-objective algorithms are analyzed: one based on Multi-objective Variable Neighborhood Search (MOVNS) and another on Pareto Iterated Local Search (PILS). Two literature algorithms based on MOVNS are adapted to solve the problem, resulting in the MOVNS_Ottoni and MOVNS_Arroyo variants. Also, a new perturbation procedure for the PILS is proposed, yielding the PILS1 variant. Computational experiments done over randomly generated instances show that PILS1 is statistically better than all other algorithms in relation to the cardinality, average distance, maximum distance, difference of hypervolume and epsilon metrics.
Marcelo Ferreira Rego; Marcone Jamilson Freitas Souza; Igor Machado Coelho; José Elias Claudio Arroyo. Multi-objective Algorithms for the Single Machine Scheduling Problem with Sequence-dependent Family Setups. Advances in Intelligent Systems and Computing 2013, 117 -127.
AMA StyleMarcelo Ferreira Rego, Marcone Jamilson Freitas Souza, Igor Machado Coelho, José Elias Claudio Arroyo. Multi-objective Algorithms for the Single Machine Scheduling Problem with Sequence-dependent Family Setups. Advances in Intelligent Systems and Computing. 2013; ():117-127.
Chicago/Turabian StyleMarcelo Ferreira Rego; Marcone Jamilson Freitas Souza; Igor Machado Coelho; José Elias Claudio Arroyo. 2013. "Multi-objective Algorithms for the Single Machine Scheduling Problem with Sequence-dependent Family Setups." Advances in Intelligent Systems and Computing , no. : 117-127.
In the Single Vehicle Routing Problem with Deliveries and Selective Pickups (SVRP-DSP) deliveries have to be made to a set of customers and there are also pickup goods to be collected. Although pickups are not obligatory, there is a revenue associated with them. Practical applications of this optimization problem arise in reverse logistics, in which customers return goods back to the depot such as in postal logistics. The SVRPDSP is a NP-hard problem, once it can be reduced to the Traveling Salesman Problem when there aren't any pickups to be made. To solve the problem at hand we propose a hybrid heuristic algorithm, named HGVNS, inspired on the metaheuristic General Variable Neighborhood Search combined with an initial solution generation by means of exact methods. The results show that HGVNS is able to find near optimal solutions and, on average, it performs better than the best known algorithm in literature.
I.M. Coelho; P.L.A. Munhoz; M.N. Haddad; M.J.F. Souza; L.S. Ochi. A hybrid heuristic based on General Variable Neighborhood Search for the Single Vehicle Routing Problem with Deliveries and Selective Pickups. Electronic Notes in Discrete Mathematics 2012, 39, 99 -106.
AMA StyleI.M. Coelho, P.L.A. Munhoz, M.N. Haddad, M.J.F. Souza, L.S. Ochi. A hybrid heuristic based on General Variable Neighborhood Search for the Single Vehicle Routing Problem with Deliveries and Selective Pickups. Electronic Notes in Discrete Mathematics. 2012; 39 ():99-106.
Chicago/Turabian StyleI.M. Coelho; P.L.A. Munhoz; M.N. Haddad; M.J.F. Souza; L.S. Ochi. 2012. "A hybrid heuristic based on General Variable Neighborhood Search for the Single Vehicle Routing Problem with Deliveries and Selective Pickups." Electronic Notes in Discrete Mathematics 39, no. : 99-106.
Marcone Souza; I.M. Coelho; S. Ribas; H.G. Santos; L.H.C. Merschmann. A hybrid heuristic algorithm for the open-pit-mining operational planning problem. European Journal of Operational Research 2010, 207, 1041 -1051.
AMA StyleMarcone Souza, I.M. Coelho, S. Ribas, H.G. Santos, L.H.C. Merschmann. A hybrid heuristic algorithm for the open-pit-mining operational planning problem. European Journal of Operational Research. 2010; 207 (2):1041-1051.
Chicago/Turabian StyleMarcone Souza; I.M. Coelho; S. Ribas; H.G. Santos; L.H.C. Merschmann. 2010. "A hybrid heuristic algorithm for the open-pit-mining operational planning problem." European Journal of Operational Research 207, no. 2: 1041-1051.
S. Ribas; M. H. P. Perché; I. M. Coelho; P. L. A. Munhoz; M. J. F. Souza; A. L. L. Aquino. MaPI: Um Framework para Paralelização de Algoritmos. Learning and Nonlinear Models 2010, 8, 163 -173.
AMA StyleS. Ribas, M. H. P. Perché, I. M. Coelho, P. L. A. Munhoz, M. J. F. Souza, A. L. L. Aquino. MaPI: Um Framework para Paralelização de Algoritmos. Learning and Nonlinear Models. 2010; 8 (3):163-173.
Chicago/Turabian StyleS. Ribas; M. H. P. Perché; I. M. Coelho; P. L. A. Munhoz; M. J. F. Souza; A. L. L. Aquino. 2010. "MaPI: Um Framework para Paralelização de Algoritmos." Learning and Nonlinear Models 8, no. 3: 163-173.
S. Ribas; M.H. De P. Perché; I.M. Coelho; P.L. Araújo Munhoz; Marcone Souza; A.L.L. Aquino. A Framework for Developing Parallel Optimization Algorithms. Informatics 2010, 1 .
AMA StyleS. Ribas, M.H. De P. Perché, I.M. Coelho, P.L. Araújo Munhoz, Marcone Souza, A.L.L. Aquino. A Framework for Developing Parallel Optimization Algorithms. Informatics. 2010; ():1.
Chicago/Turabian StyleS. Ribas; M.H. De P. Perché; I.M. Coelho; P.L. Araújo Munhoz; Marcone Souza; A.L.L. Aquino. 2010. "A Framework for Developing Parallel Optimization Algorithms." Informatics , no. : 1.