Pub Date : 2019-08-03DOI: 10.22456/2175-2745.86534
A. C. R. Costa
This paper formally characterizes the elementary economic systems of material agent societies, on the bases of the notions of (individual and group) elementary economic behavior, elementary economic exchange and elementary economic process. The equilibrium of an elementary economic system is defined in terms of the equilibrium of the set of group elementary economic processes that constitute such system. A case study illustrates the proposed concepts.
{"title":"Elementary Economic Systems in Material Agent Societies","authors":"A. C. R. Costa","doi":"10.22456/2175-2745.86534","DOIUrl":"https://doi.org/10.22456/2175-2745.86534","url":null,"abstract":"This paper formally characterizes the elementary economic systems of material agent societies, on the bases of the notions of (individual and group) elementary economic behavior, elementary economic exchange and elementary economic process. The equilibrium of an elementary economic system is defined in terms of the equilibrium of the set of group elementary economic processes that constitute such system. A case study illustrates the proposed concepts.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90356852","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}
Pub Date : 2019-04-14DOI: 10.22456/2175-2745.84814
L. Digiampietri, V. Pereira, Geraldo José Santos-Júnior, Giovani Sousa-Leite, Priscilla Koch Wagner, L. M. Moreira, C. Santiago
Most of the computational biology analysis is made comparing genomic features. The nucleotide and amino acid sequence alignments are frequently used in gene function identification and genome comparison. Despite its widespread use, there are limitations in their analysis capabilities that need to be considered but are often overlooked or unknown by many researchers. This paper presents a gene based whole genome comparison toolkit which can be used not only as an alternative and more robust way to compare a set of whole genomes, but, also, to understand the tradeoff of the use of sequence local alignment in this kind of comparison. A study case was performed considering fifteen whole genomes of the Xanthomonas genus. The results were compared with the 16S rRNA-processing protein RimM phylogeny and some thresholds for the use of sequence alignments in this kind of analysis were discussed.
{"title":"A gene based bacterial whole genome comparison toolkit","authors":"L. Digiampietri, V. Pereira, Geraldo José Santos-Júnior, Giovani Sousa-Leite, Priscilla Koch Wagner, L. M. Moreira, C. Santiago","doi":"10.22456/2175-2745.84814","DOIUrl":"https://doi.org/10.22456/2175-2745.84814","url":null,"abstract":"Most of the computational biology analysis is made comparing genomic features. The nucleotide and amino acid sequence alignments are frequently used in gene function identification and genome comparison. Despite its widespread use, there are limitations in their analysis capabilities that need to be considered but are often overlooked or unknown by many researchers. This paper presents a gene based whole genome comparison toolkit which can be used not only as an alternative and more robust way to compare a set of whole genomes, but, also, to understand the tradeoff of the use of sequence local alignment in this kind of comparison. A study case was performed considering fifteen whole genomes of the Xanthomonas genus. The results were compared with the 16S rRNA-processing protein RimM phylogeny and some thresholds for the use of sequence alignments in this kind of analysis were discussed.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83872823","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}
Pub Date : 2019-04-14DOI: 10.22456/2175-2745.84330
M. Spohn, Matheus Henrique Trichez
Better understanding mobility, being it from pedestrians or any other moving object, is practical and insightful. Practical due to its applications to the fundamentals of communication, with special attention to wireless communication. Insightful because it might pinpoint the pros and cons of how we are moving, or being moved, around. There are plenty of studies focused on mobility in mobile wireless networks, including the proposals of several synthetic mobility models. Getting real mobility traces is not an easy task, but there has been some efforts to provide traces to the public through repositories. Synthetic mobility models are usually analyzed through mobility metrics, which are designed to capture mobility subtleties. This work research on the applicability of some representative mobility metrics for real traces analysis. To achieve that goal, a case study is accomplished with a dataset of mobility traces of taxi cabs in the city of Rome/Italy. The results suggest that the mobility metrics under consideration are capable of capturing mobility properties which would otherwise require more sophisticated analytical approaches.
{"title":"An Analysis of a Real Mobility Trace Based on Standard Mobility Metrics","authors":"M. Spohn, Matheus Henrique Trichez","doi":"10.22456/2175-2745.84330","DOIUrl":"https://doi.org/10.22456/2175-2745.84330","url":null,"abstract":"Better understanding mobility, being it from pedestrians or any other moving object, is practical and insightful. Practical due to its applications to the fundamentals of communication, with special attention to wireless communication. Insightful because it might pinpoint the pros and cons of how we are moving, or being moved, around. There are plenty of studies focused on mobility in mobile wireless networks, including the proposals of several synthetic mobility models. Getting real mobility traces is not an easy task, but there has been some efforts to provide traces to the public through repositories. Synthetic mobility models are usually analyzed through mobility metrics, which are designed to capture mobility subtleties. This work research on the applicability of some representative mobility metrics for real traces analysis. To achieve that goal, a case study is accomplished with a dataset of mobility traces of taxi cabs in the city of Rome/Italy. The results suggest that the mobility metrics under consideration are capable of capturing mobility properties which would otherwise require more sophisticated analytical approaches.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89085639","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}
Pub Date : 2019-04-14DOI: 10.22456/2175-2745.86380
Diógenes Antonio Marques José, R. B. Neto, Vinícius Sebba-Patto, I. G. S. Júnior
The mobile ad-hoc networks (MANET) are those whose nodes have mobility, energy restriction and operate simultaneously as end systems and router. One of the main problems found in MANETs is the occurrence of selfish nodes, which are those that refuse to route packets for other nodes. To address the issue of selfish nodes in MANETs and improve the flow of traffic in these networks, this paper proposes an extension to the OLSR protocol, based on Fuzzy logic, called OLSR Fuzzy Cost (OLSR -FC). Using the NS-2 simulator, the OLSR-FC proposal was compared to other extensions of OLSR protocol (e.g., OLSR-ETX, OLSR-ML e OLSR-MD) concerning the performance metrics: packet loss, end-to-end delay, Jitter, power consumption, routing overhead and throughput. The results showed that OLSR-FC obtains better performance than the evaluated extensions, avoiding selfish nodes and selecting routes whose links have little packet losses.
{"title":"OLSR Fuzzy Cost (OLSR-FC): an extension to OLSR protocol based on fuzzy logic and applied to avoid selfish nodes","authors":"Diógenes Antonio Marques José, R. B. Neto, Vinícius Sebba-Patto, I. G. S. Júnior","doi":"10.22456/2175-2745.86380","DOIUrl":"https://doi.org/10.22456/2175-2745.86380","url":null,"abstract":"The mobile ad-hoc networks (MANET) are those whose nodes have mobility, energy restriction and operate simultaneously as end systems and router. One of the main problems found in MANETs is the occurrence of selfish nodes, which are those that refuse to route packets for other nodes. To address the issue of selfish nodes in MANETs and improve the flow of traffic in these networks, this paper proposes an extension to the OLSR protocol, based on Fuzzy logic, called OLSR Fuzzy Cost (OLSR -FC). Using the NS-2 simulator, the OLSR-FC proposal was compared to other extensions of OLSR protocol (e.g., OLSR-ETX, OLSR-ML e OLSR-MD) concerning the performance metrics: packet loss, end-to-end delay, Jitter, power consumption, routing overhead and throughput. The results showed that OLSR-FC obtains better performance than the evaluated extensions, avoiding selfish nodes and selecting routes whose links have little packet losses.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81443673","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}
Pub Date : 2019-04-14DOI: 10.22456/2175-2745.86196
Guilherme Panizzon, Joao Henrique Faes Battisti, G. Koslovski, M. A. Pillon, C. Miers
VirtualizationincloudcomputinghasbeenusedincombinationwithenvironmentsPlatformas a Service (PaaS) and Infrastructure as a Service (IaaS) in order to provide performance, isolation, and scalability. However, containers and virtual machines (VMs) are susceptible to the vulnerabilities present in the core of operating system as well as container solutions, which are a risk for information and service operation of all entities sharing a same host. The safety recommendation guides aims to mitigate the security in this scenario, but the selection of containerization solutions taking into account security requirements is a complex task. Thus, we propose a security taxonomy focused on containers to cloud computing in order to assist the classification and evaluation containers security mechanisms and solutions.
{"title":"A Taxonomy of container security on computational clouds: concerns and solutions","authors":"Guilherme Panizzon, Joao Henrique Faes Battisti, G. Koslovski, M. A. Pillon, C. Miers","doi":"10.22456/2175-2745.86196","DOIUrl":"https://doi.org/10.22456/2175-2745.86196","url":null,"abstract":"VirtualizationincloudcomputinghasbeenusedincombinationwithenvironmentsPlatformas a Service (PaaS) and Infrastructure as a Service (IaaS) in order to provide performance, isolation, and scalability. However, containers and virtual machines (VMs) are susceptible to the vulnerabilities present in the core of operating system as well as container solutions, which are a risk for information and service operation of all entities sharing a same host. The safety recommendation guides aims to mitigate the security in this scenario, but the selection of containerization solutions taking into account security requirements is a complex task. Thus, we propose a security taxonomy focused on containers to cloud computing in order to assist the classification and evaluation containers security mechanisms and solutions.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72538042","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}
Pub Date : 2019-04-14DOI: 10.22456/2175-2745.87511
R. Yadav, Gleidson A. S. Campos, E. Sousa, F. Lins
On-demand services and reduced costs made cloud computing a popular mechanism to provide scalable resources according to the user’s expectations. This paradigm is an important role in business and academic organizations, supporting applications and services deployed based on virtual machines and containers, two different technologies for virtualization. Cloud environments can support workloads generated by several numbers of users, that request the cloud environment to execute transactions and its performance should be evaluated and estimated in order to achieve clients satisfactions when cloud services are offered. This work proposes a performance evaluation strategy composed of a performance model and a methodology for evaluating the performance of services configured in virtual machines and containers in cloud infrastructures. The performance model for the evaluation of virtual machines and containers in cloud infrastructures is based on stochastic Petri nets. A case study in a real public cloud is presented to illustrate the feasibility of the performance evaluation strategy. The case study experiments were performed with virtual machines and containers supporting workloads related to social networks transactions.
{"title":"A Strategy for Performance Evaluation and Modeling of Cloud Computing Services","authors":"R. Yadav, Gleidson A. S. Campos, E. Sousa, F. Lins","doi":"10.22456/2175-2745.87511","DOIUrl":"https://doi.org/10.22456/2175-2745.87511","url":null,"abstract":"On-demand services and reduced costs made cloud computing a popular mechanism to provide scalable resources according to the user’s expectations. This paradigm is an important role in business and academic organizations, supporting applications and services deployed based on virtual machines and containers, two different technologies for virtualization. Cloud environments can support workloads generated by several numbers of users, that request the cloud environment to execute transactions and its performance should be evaluated and estimated in order to achieve clients satisfactions when cloud services are offered. This work proposes a performance evaluation strategy composed of a performance model and a methodology for evaluating the performance of services configured in virtual machines and containers in cloud infrastructures. The performance model for the evaluation of virtual machines and containers in cloud infrastructures is based on stochastic Petri nets. A case study in a real public cloud is presented to illustrate the feasibility of the performance evaluation strategy. The case study experiments were performed with virtual machines and containers supporting workloads related to social networks transactions.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73972335","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}
Pub Date : 2019-04-14DOI: 10.22456/2175-2745.82412
Bruno Well Dantas Morais, G. Oliveira, T. I. D. Carvalho
This work presents the development of a multipopulation genetic algorithm for the task schedulingproblem with communication costs, aiming to compare its performance with the serial genetic algorithm. For thispurpose, a set of instances was developed and different approaches for genetic operations were compared.Experiments were conducted varying the number of populations and the number of processors available forscheduling. Solution quality and execution time were analyzed, and results show that the AGMP with adjustedparameters generally produces better solutions while requiring less execution time.
{"title":"Evolutionary Models applied to Multiprocessor TaskScheduling: Serial and Multipopulation Genetic Algorithm","authors":"Bruno Well Dantas Morais, G. Oliveira, T. I. D. Carvalho","doi":"10.22456/2175-2745.82412","DOIUrl":"https://doi.org/10.22456/2175-2745.82412","url":null,"abstract":"This work presents the development of a multipopulation genetic algorithm for the task schedulingproblem with communication costs, aiming to compare its performance with the serial genetic algorithm. For thispurpose, a set of instances was developed and different approaches for genetic operations were compared.Experiments were conducted varying the number of populations and the number of processors available forscheduling. Solution quality and execution time were analyzed, and results show that the AGMP with adjustedparameters generally produces better solutions while requiring less execution time.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90491884","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}
Pub Date : 2018-11-19DOI: 10.22456/2175-2745.80702
C. M. Saporetti, G. R. Duarte, Tales L. Fonseca, L. G. Fonseca, E. Pereira
Lithology identification, obtained through the analysis of several geophysical properties, has an important role in the process of characterization of oil reservoirs. The identification can be accomplished by direct and indirect methods, but these methods are not always feasible because of the cost or imprecision of the results generated. Consequently, there is a need to automate the procedure of reservoir characterization and, in this context, computational intelligence techniques appear as an alternative to lithology identification. However, to acquire proper performance, usually some parameters should be adjusted and this can become a hard task depending on the complexity of the underlying problem. This paper aims to apply an Extreme Learning Machine (ELM) adjusted with a Differential Evolution (DE) to classify data from the South Provence Basin, using a previously published paper as a baseline reference. The paper contributions include the use of an evolutionary algorithm as a tool for search on the hyperparameters of the ELM. In addition, an activation function recently proposed in the literature is implemented and tested. The computational approach developed here has the potential to assist in petrographic data classification and helps to improve the process of reservoir characterization and the production development planning.
{"title":"Extreme Learning Machine combined with a Differential Evolution algorithm for lithology identification","authors":"C. M. Saporetti, G. R. Duarte, Tales L. Fonseca, L. G. Fonseca, E. Pereira","doi":"10.22456/2175-2745.80702","DOIUrl":"https://doi.org/10.22456/2175-2745.80702","url":null,"abstract":"Lithology identification, obtained through the analysis of several geophysical properties, has an important role in the process of characterization of oil reservoirs. The identification can be accomplished by direct and indirect methods, but these methods are not always feasible because of the cost or imprecision of the results generated. Consequently, there is a need to automate the procedure of reservoir characterization and, in this context, computational intelligence techniques appear as an alternative to lithology identification. However, to acquire proper performance, usually some parameters should be adjusted and this can become a hard task depending on the complexity of the underlying problem. This paper aims to apply an Extreme Learning Machine (ELM) adjusted with a Differential Evolution (DE) to classify data from the South Provence Basin, using a previously published paper as a baseline reference. The paper contributions include the use of an evolutionary algorithm as a tool for search on the hyperparameters of the ELM. In addition, an activation function recently proposed in the literature is implemented and tested. The computational approach developed here has the potential to assist in petrographic data classification and helps to improve the process of reservoir characterization and the production development planning.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79420175","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}
Pub Date : 2018-11-19DOI: 10.22456/2175-2745.80721
A. M. D. Lima, R. Carmo
The graph coloring problem is the problem of partitioning the vertices of a graph into the smallest possible set of independent sets. Since it is a well-known NP-Hard problem, it is of great interest of the computer science finding results over exact algorithms that solve it. The main algorithms of this kind, though, are scattered through the literature. In this paper, we group and contextualize some of these algorithms, which are based in Dynamic Programming, Branch-and-Bound and Integer Linear Programming. The algorithms for the first group are based in the work of Lawler, which searches maximal independent sets on each subset of vertices of a graph as the base of his algorithm. In the second group, the algorithms are based in the work of Brelaz, which adapted the DSATUR procedure to an exact version, and in the work of Zykov, which introduced the definition of Zykov trees. The third group contains the algorithms based in the work of Mehrotra and Trick, which uses the Column Generation method.
{"title":"Exact Algorithms for the Graph Coloring Problem","authors":"A. M. D. Lima, R. Carmo","doi":"10.22456/2175-2745.80721","DOIUrl":"https://doi.org/10.22456/2175-2745.80721","url":null,"abstract":"The graph coloring problem is the problem of partitioning the vertices of a graph into the smallest possible set of independent sets. Since it is a well-known NP-Hard problem, it is of great interest of the computer science finding results over exact algorithms that solve it. The main algorithms of this kind, though, are scattered through the literature. In this paper, we group and contextualize some of these algorithms, which are based in Dynamic Programming, Branch-and-Bound and Integer Linear Programming. The algorithms for the first group are based in the work of Lawler, which searches maximal independent sets on each subset of vertices of a graph as the base of his algorithm. In the second group, the algorithms are based in the work of Brelaz, which adapted the DSATUR procedure to an exact version, and in the work of Zykov, which introduced the definition of Zykov trees. The third group contains the algorithms based in the work of Mehrotra and Trick, which uses the Column Generation method.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81500438","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}
Pub Date : 2018-11-19DOI: 10.22456/2175-2745.80525
C. Burt, Alysson M. Costa, C. Ras
We study the problem of constructing minimum power-$p$ Euclidean $k$-Steiner trees in the plane. The problem is to find a tree of minimum cost spanning a set of given terminals where, as opposed to the minimum spanning tree problem, at most $k$ additional nodes (Steiner points) may be introduced anywhere in the plane. The cost of an edge is its length to the power of $p$ (where $pgeq 1$), and the cost of a network is the sum of all edge costs. We propose two heuristics: a ``beaded" minimum spanning tree heuristic; and a heuristic which alternates between minimum spanning tree construction and a local fixed topology minimisation procedure for locating the Steiner points. We show that the performance ratio $kappa$ of the beaded-MST heuristic satisfies $sqrt{3}^{p-1}(1+2^{1-p})leq kappaleq 3(2^{p-1})$. We then provide two mixed-integer nonlinear programming formulations for the problem, and extend several important geometric properties into valid inequalities. Finally, we combine the valid inequalities with warm-starting and preprocessing to obtain computational improvements for the $p=2$ case.
{"title":"Algorithms for the power-p Steiner tree problem in the Euclidean plane","authors":"C. Burt, Alysson M. Costa, C. Ras","doi":"10.22456/2175-2745.80525","DOIUrl":"https://doi.org/10.22456/2175-2745.80525","url":null,"abstract":"We study the problem of constructing minimum power-$p$ Euclidean $k$-Steiner trees in the plane. The problem is to find a tree of minimum cost spanning a set of given terminals where, as opposed to the minimum spanning tree problem, at most $k$ additional nodes (Steiner points) may be introduced anywhere in the plane. The cost of an edge is its length to the power of $p$ (where $pgeq 1$), and the cost of a network is the sum of all edge costs. We propose two heuristics: a ``beaded\" minimum spanning tree heuristic; and a heuristic which alternates between minimum spanning tree construction and a local fixed topology minimisation procedure for locating the Steiner points. We show that the performance ratio $kappa$ of the beaded-MST heuristic satisfies $sqrt{3}^{p-1}(1+2^{1-p})leq kappaleq 3(2^{p-1})$. We then provide two mixed-integer nonlinear programming formulations for the problem, and extend several important geometric properties into valid inequalities. Finally, we combine the valid inequalities with warm-starting and preprocessing to obtain computational improvements for the $p=2$ case.","PeriodicalId":82472,"journal":{"name":"Research initiative, treatment action : RITA","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74649234","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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