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Hybrid genetic algorithm for undirected traveling salesman problems with profits 求解有利润无向旅行商问题的混合遗传算法
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-06-21 DOI: 10.1002/net.22167
P. He, Jin-Kao Hao, Qinghua Wu
The orienteering problem (OP) and prize‐collecting traveling salesman problem (PCTSP) are two typical TSPs with profits, in which each vertex has a profit and the goal is to visit several vertices to optimize the collected profit and travel costs. The OP aims to collect the maximum profit without exceeding the given travel cost. The PCTSP seeks to minimize the travel costs while ensuring a minimum profit threshold. This study introduces a hybrid genetic algorithm that addresses both the OP and PCTSP under a unified framework. The algorithm combines an extended edge‐assembly crossover operator to produce promising offspring solutions, and an effective local search to ameliorate each offspring solution. The algorithm is further enforced by diversification‐oriented mutation and population‐diversity management. Extensive experiments demonstrate that the method competes favorably with the best existing methods in terms of both the solution quality and computational efficiency. Additional experiments provide insights into the roles of the key components of the proposed method.
定向越野问题(OP)和奖品收集旅行推销员问题(PCTSP)是两个典型的有利润的TSP,其中每个顶点都有利润,目标是访问几个顶点以优化收集的利润和旅行成本。OP的目标是在不超过给定差旅成本的情况下获得最大利润。PCTSP旨在最大限度地降低差旅成本,同时确保最低利润阈值。本研究介绍了一种混合遗传算法,该算法在统一的框架下同时解决OP和PCTSP问题。该算法结合了一个扩展的边缘组装交叉算子来产生有前景的子代解决方案,以及一个有效的局部搜索来改进每一个子代解决方案。该算法通过面向多样化的突变和种群多样性管理得到进一步加强。大量实验表明,该方法在求解质量和计算效率方面都与现有的最佳方法相竞争。额外的实验提供了对所提出的方法的关键组成部分的作用的见解。
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引用次数: 1
A survey on exact algorithms for the maximum flow and minimum‐cost flow problems 最大流量和最小成本流量问题的精确算法综述
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-06-20 DOI: 10.1002/net.22169
O. Cruz-Mejía, A. Letchford
Network flow problems form an important and much‐studied family of combinatorial optimization problems, with a huge array of practical applications. Two network flow problems in particular have received a great deal of attention: the maximum flow and minimum‐cost flow problems. We review the progress that has been made on exact solution algorithms for these two problems, with an emphasis on worst‐case running times.
网络流问题是一类重要且研究较多的组合优化问题,具有大量的实际应用。特别是两个网络流量问题受到了极大的关注:最大流量和最小成本流量问题。我们回顾了这两个问题的精确求解算法的进展,重点是最坏情况下的运行时间。
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引用次数: 6
Achieving feasibility for clustered traveling salesman problems using PQ‐trees 利用PQ‐树实现聚类旅行推销员问题的可行性
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-06-15 DOI: 10.1002/net.22164
Nili Guttmann-Beck, Hadas Meshita‐Sayag, Michal Stern
Let H=⟨V,𝒮⟩ be a hypergraph, where V$$ V $$ is a set of vertices and 𝒮 is a set of clusters S1,…,Sm$$ {S}_1,dots, {S}_m $$ , Si⊆V$$ {S}_isubseteq V $$ , such that the clusters in 𝒮 are not necessarily disjoint. This article considers the feasibility clustered traveling salesman problem, denoted by FCTSP$$ FCTSP $$ . In the FCTSP$$ FCTSP $$ we aim to decide whether a simple path exists that visits each vertex exactly once, such that the vertices of each cluster are visited consecutively. We focus on hypergraphs with no feasible solution path and consider removing vertices from clusters, such that the hypergraph with the new clusters has a feasible solution path for FCTSP$$ FCTSP $$ . The algorithm uses a PQ‐tree data structure and runs in linear time.
设H=⟨V,𝒮⟩ 是超图,其中V$$V$$是一组顶点𝒮 是一组簇S1,…,Sm$${S}_1,点,{S}_m$$,Si⊆V$${S}_isubsteq V$$,使得𝒮 不一定是不相交的。本文考虑可行性聚类旅行推销员问题,用FCTSP$$FCTSP$$表示。在FCTSP$$FCTSP$$中,我们的目标是确定是否存在只访问每个顶点一次的简单路径,以便连续访问每个簇的顶点。我们关注没有可行解路径的超图,并考虑从簇中移除顶点,使得具有新簇的超图对于FCTSP$$FCTSP$$具有可行解路径。该算法使用PQ树数据结构,并在线性时间内运行。
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引用次数: 0
Exact solution approaches for the discrete α‐neighbor p‐center problem 离散α近邻p中心问题的精确解方法
4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-06-13 DOI: 10.1002/net.22162
Elisabeth Gaar, Markus Sinnl
The discrete ‐neighbor ‐center problem (d‐‐CP) is an emerging variant of the classical ‐center problem which recently got attention in literature. In this problem, we are given a discrete set of points and we need to locate facilities on these points in such a way that the maximum distance between each point where no facility is located and its ‐closest facility is minimized. The only existing algorithms in literature for solving the d‐‐CP are approximation algorithms and two recently proposed heuristics. In this work, we present two integer programming formulations for the d‐‐CP, together with lifting of inequalities, valid inequalities, inequalities that do not change the optimal objective function value and variable fixing procedures. We provide theoretical results on the strength of the formulations and convergence results for the lower bounds obtained after applying the lifting procedures or the variable fixing procedures in an iterative fashion. Based on our formulations and theoretical results, we develop branch‐and‐cut (B&C ) algorithms, which are further enhanced with a starting heuristic and a primal heuristic. We evaluate the effectiveness of our B&C algorithms using instances from literature. Our algorithms are able to solve 116 out of 194 instances from literature to proven optimality, with a runtime of under a minute for most of them. By doing so, we also provide improved solution values for 116 instances.
离散邻近中心问题(d - CP)是近年来在文献中引起关注的经典中心问题的一个新变体。在这个问题中,我们有一个离散的点集,我们需要在这些点上定位设施,使每个没有设施的点与其最近的设施之间的最大距离最小。文献中仅有的求解d‐‐CP的算法是近似算法和最近提出的两种启发式算法。在这项工作中,我们提出了d‐‐CP的两个整数规划公式,以及不等式的解除,有效不等式,不改变最优目标函数值的不等式和变量的固定过程。我们提供了关于公式强度的理论结果和在迭代方式下应用提升程序或变量固定程序后得到的下界的收敛结果。基于我们的公式和理论结果,我们开发了分支和切断(B&C)算法,该算法通过起始启发式和原始启发式进一步增强。我们使用文献中的实例来评估我们的B&C算法的有效性。我们的算法能够解决194个实例中的116个,从文献到已证明的最优性,其中大多数的运行时间不到一分钟。通过这样做,我们还为116个实例提供了改进的解决方案值。
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引用次数: 0
Node based compact formulations for the Hamiltonian p‐median problem 哈密顿p中值问题的基于节点的紧化公式
4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-06-09 DOI: 10.1002/net.22163
Michele Barbato, Francisco Canas, Luís Gouveia, Pierre Pesneau
Abstract In this paper, we introduce, study and analyze several classes of compact formulations for the symmetric Hamiltonian ‐median problem (HMP). Given a positive integer and a weighted complete undirected graph with weights on the edges, the HMP on is to find a minimum weight set of elementary cycles partitioning the vertices of . The advantage of developing compact formulations is that they can be readily used in combination with off‐the‐shelf optimization software, unlike other types of formulations possibly involving the use of exponentially sized sets of variables or constraints. The main part of the paper focuses on compact formulations for eliminating solutions with less than cycles. Such formulations are less well known and studied than formulations which prevent solutions with more than cycles. The proposed formulations are based on a common motivation, that is, the formulations contain variables that assign labels to nodes, and prevent less than cycles by stating that different depots must have different labels and that nodes in the same cycle must have the same label. We introduce and study aggregated formulations (which consider integer variables that represent the label of the node) and disaggregated formulations (which consider binary variables that assign each node to a given label). The aggregated models are new. The disaggregated formulations are not, although in all of them new enhancements have been included to make them more competitive with the aggregated models. The two main conclusions of this study are: (i) in the context of compact formulations, it is worth looking at the models with integer node variables, which have a smaller size. Despite their weaker LP relaxation bounds, the fewer variables and constraints lead to faster integer resolution, especially when solving instances with more than 50 nodes; (ii) the best of our compact models exhibit a performance that, overall, is comparable to that of the best methods known for the HMP (including branch‐and‐cut algorithms), solving to optimality instances with up to 226 nodes within 1 h. This corroborates our message that the knowledge of the inequalities for preventing less than cycles is much less well understood.
摘要本文引入、研究和分析了对称哈密顿中值问题(HMP)的几类紧化公式。给定一个正整数和一个边上有权的加权完全无向图,HMP的目的是找到一个最小权的初等环集来划分图的顶点。开发紧凑公式的优势在于,它们可以很容易地与现成的优化软件结合使用,而不像其他类型的公式可能涉及使用指数大小的变量或约束集。论文的主要部分着重于消除小于循环的解的紧化公式。这种配方比那些防止溶液循环次数多于循环的配方更不为人所知和研究。建议的公式基于一个共同的动机,即公式包含为节点分配标签的变量,并通过声明不同的仓库必须具有不同的标签,同一循环中的节点必须具有相同的标签来防止小于循环。我们引入并研究了聚合公式(考虑代表节点标签的整数变量)和分解公式(考虑将每个节点分配给给定标签的二进制变量)。聚合模型是新的。分解的公式不是,尽管在所有这些公式中都包含了新的增强功能,使它们与聚合模型更具竞争力。本研究的两个主要结论是:(i)在紧凑公式的背景下,值得研究具有较小尺寸的整数节点变量的模型。尽管它们的LP松弛界限较弱,但较少的变量和约束导致更快的整数分辨率,特别是在解决超过50个节点的实例时;(ii)我们最好的紧凑模型表现出的性能,总体而言,与已知的HMP最佳方法(包括分支和切断算法)相当,在1小时内求解最多226个节点的最优实例。这证实了我们的信息,即防止小于循环的不等式知识知之甚少。
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引用次数: 0
Issue Information 问题信息
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-06-09 DOI: 10.1002/net.22106
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引用次数: 0
On the split reliability of graphs 关于图的分裂可靠性
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-06-06 DOI: 10.1002/net.22166
Jason I. Brown, Isaac McMullin
A common model of robustness of a graph against random failures has all vertices operational, but the edges independently operational with probability p$$ p $$ . One can ask for the probability that all vertices can communicate (all‐terminal reliability) or that two specific vertices (or terminals) can communicate with each other (two‐terminal reliability). A relatively new measure is split reliability, where for two fixed vertices s$$ s $$ and t$$ t $$ , we consider the probability that every vertex communicates with one of s$$ s $$ or t$$ t $$ , but not both. In this article, we explore the existence for fixed numbers n≥2$$ nge 2 $$ and m≥n−1$$ mge n-1 $$ of an optimal connected (n,m)$$ left(n,mright) $$ ‐graph Gn,m$$ {G}_{n,m} $$ for split reliability, that is, a connected graph with n$$ n $$ vertices and m$$ m $$ edges for which for any other such graph H$$ H $$ , the split reliability of Gn,m$$ {G}_{n,m} $$ is at least as large as that of H$$ H $$ , for all values of p∈[0,1]$$ pin left[0,1right] $$ . Unlike the similar problems for all‐terminal and two‐terminal reliability, where only partial results are known, we completely solve the issue for split reliability, where we show that there is an optimal (n,m)$$ left(n,mright) $$ ‐graph for split reliability if and only if n≤3$$ nle 3 $$ , m=n−1$$ m=n-1 $$ , or n=m=4$$ n=m=4 $$ .
图对随机故障的鲁棒性的一个常见模型使所有顶点都可操作,但边以概率p$$p$$独立操作。可以询问所有顶点都可以通信的概率(全终端可靠性)或两个特定顶点(或终端)可以相互通信的可能性(双终端可靠性)。一个相对较新的度量是分裂可靠性,其中对于两个固定顶点s$$s$$和t$$t$$,我们考虑每个顶点与s$$s$$或t$$t$$中的一个通信的概率,但不是两者都通信。在这篇文章中,我们探讨了最优连通(n,m)$$left(n,mright)$$图Gn,m$$的不动点n≥2$$ge 2$$和m≥n-1$$ge n-1$$的存在性{G}_{n,m}$$的分裂可靠性,即具有n$$n$$顶点和m$$m$$边的连通图,对于任何其他这样的图H$$H$$,Gn,m$$的分割可靠性{G}_对于p∈[0,1]$pinleft[0,1right]$$的所有值,{n,m}$$至少与H$$H$$一样大。与只有部分结果已知的所有终端和两终端可靠性的类似问题不同,我们完全解决了分裂可靠性的问题,其中我们证明了分裂可靠性存在一个最优(n,m)$$left(n,mright)$$图当且仅当n≤3$$nle 3$$,m=n−1$$m=n-1$$,或n=m=4$$n=4$$。
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引用次数: 0
Solving the time capacitated arc routing problem under fuzzy and stochastic travel and service times 模糊随机行程和服务时间下的时间容量弧路由问题的求解
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-05-22 DOI: 10.1002/net.22159
Xabier A. Martin, Javier Panadero, David Peidro, E. Pérez-Bernabeu, A. Juan
Stochastic, as well as fuzzy uncertainty, can be found in most real‐world systems. Considering both types of uncertainties simultaneously makes optimization problems incredibly challenging. In this paper we propose a fuzzy simheuristic to solve the Time Capacitated Arc Routing Problem (TCARP) when the nature of the travel time can either be deterministic, stochastic or fuzzy. The main goal is to find a solution (vehicle routes) that minimizes the total time spent in servicing the required arcs. However, due to uncertainty, other characteristics of the solution are also considered. In particular, we illustrate how reliability concepts can enrich the probabilistic information given to decision‐makers. In order to solve the aforementioned optimization problem, we extend the concept of simheuristic framework so it can also include fuzzy elements. Hence, both stochastic and fuzzy uncertainty are simultaneously incorporated into the CARP. In order to test our approach, classical CARP instances have been adapted and extended so that customers' demands become either stochastic or fuzzy. The experimental results show the effectiveness of the proposed approach when compared with more traditional ones. In particular, our fuzzy simheuristic is capable of generating new best‐known solutions for the stochastic versions of some instances belonging to the tegl, tcarp, val, and rural benchmarks.
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引用次数: 1
Risk‐averse optimization and resilient network flows 风险规避优化和弹性网络流
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-05-13 DOI: 10.1002/net.22149
Masoud Eshghali, P. Krokhmal
We propose an approach to constructing metrics of network resilience, where resilience is understood as the network's amenability to restoring its optimal or near‐optimal operations subsequent to unforeseen (stochastic) disruptions of its topology or operational parameters, and illustrated it on the examples of the resilient maximum network flow problem and the resilient minimum cost network problem. Specifically, the network flows in these problems are designed for resilience against unpredictable losses of network carrying capacity, and the mechanism of attaining a degree of resilience is through preallocation of resources toward (at least partial) restoration of the capacities of the arcs. The obtained formulations of resilient network flow problems possess a number of useful properties, for example, similarly to the standard network flow problems, the network flow is integral if the arc capacities, costs, and so forth, are integral. It is also shown that the proposed formulations of resilient network flow problems can be viewed as “network measures of risk”, similar in properties and behavior to convex measures of risk. Efficient decomposition algorithms have been proposed for both the resilient maximum network flow problem and the resilient minimum cost network flow problem, and a study of the network flow resilience as a function of network's structure has been conducted on networks with three types of topology: that of uniform random graphs, scale‐free graphs, and grid graphs.
我们提出了一种构建网络弹性指标的方法,其中弹性被理解为网络在拓扑结构或操作参数发生意外(随机)中断后恢复其最优或接近最优操作的适应性,并以弹性最大网络流量问题和弹性最小代价网络问题为例进行了说明。具体而言,这些问题中的网络流是为抵御网络承载能力的不可预测损失而设计的,并且获得一定程度的弹性的机制是通过预先分配资源来(至少部分)恢复弧的容量。所获得的弹性网络流问题的公式具有许多有用的性质,例如,与标准网络流问题类似,如果电弧容量、成本等是积分的,则网络流是积分的。研究还表明,所提出的弹性网络流问题的公式可以被视为“风险的网络度量”,在性质和行为上类似于风险的凸度量。针对弹性最大网络流量问题和弹性最小成本网络流量问题,提出了有效的分解算法,并在具有三种拓扑类型的网络上研究了网络流量弹性作为网络结构的函数:均匀随机图、无标度图和网格图。
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引用次数: 1
Provision of maximum connectivity resiliency with minimum cost to telecommunication networks through third‐party networks 通过第三方网络,以最小的成本为电信网络提供最大的连接弹性
IF 2.1 4区 计算机科学 Q4 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE Pub Date : 2023-05-03 DOI: 10.1002/net.22148
Fábio Barbosa, A. D. de Sousa, A. Agra
In telecommunication networks, full connectivity resilience to multiple link failures is too costly as it requires a network topology with too many redundant links. Alternatively, the connectivity resilience of a telecommunications network can be improved by resorting to available third‐party networks for temporary additional connectivity until the failing links are restored. In this approach, some nodes of the network must be selected in advance to act as gateway nodes to the third‐party networks when a multiple link failure event occurs. For a given network topology and a cost associated with each node to turn it into a gateway node to each of the third‐party networks, the aim is to select the gateway nodes providing maximum connectivity resilience at minimum cost. The Gateway Node Selection is defined as a bi‐objective optimization problem such that its Pareto‐optimal solutions represent different trade‐offs between cost and connectivity resilience. In this work, the connectivity resilience is modeled by the Critical Link Detection optimization problem. An exact optimization algorithm is proposed, based on a row generation algorithm and on set cover cuts. The computational results demonstrate the effectiveness of the proposed algorithm on four well‐known telecommunication network topologies.
在电信网络中,对多链路故障的完全连接弹性需要具有过多冗余链路的网络拓扑结构,因此成本过高。另外,电信网络的连接弹性可以通过求助于可用的第三方网络来临时增加连接,直到故障链路恢复。在这种方法中,当发生多链路故障事件时,必须提前选择网络中的一些节点作为第三方网络的网关节点。对于给定的网络拓扑和与每个节点相关的成本,将其转换为每个第三方网络的网关节点,目标是选择以最小成本提供最大连接弹性的网关节点。网关节点选择被定义为一个双目标优化问题,其帕累托最优解决方案代表了成本和连接弹性之间的不同权衡。在这项工作中,连接弹性是由关键链路检测优化问题建模的。提出了一种基于行生成算法和集合覆盖切割的精确优化算法。计算结果证明了该算法在四种已知的电信网络拓扑结构上的有效性。
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引用次数: 0
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