Journal of Combinatorial Optimization最新文献

{"title":"A branch-and-cut algorithm for the balanced traveling salesman problem","authors":"Thi Quynh Trang Vo, Mourad Baiou, Viet Hung Nguyen","doi":"10.1007/s10878-023-01097-4","DOIUrl":"https://doi.org/10.1007/s10878-023-01097-4","url":null,"abstract":"<p>The balanced traveling salesman problem (BTSP) is a variant of the traveling salesman problem, in which one seeks a tour that minimizes the difference between the largest and smallest edge costs in the tour. The BTSP, which is obviously NP-hard, was first investigated by Larusic and Punnen (Comput Oper Res 38(5):868–875, 2011). They proposed several heuristics based on the double-threshold framework, which converge to good-quality solutions though not always optimal. In this paper, we design a special-purpose branch-and-cut algorithm for exactly solving the BTSP. In contrast with the classical TSP, due to the BTSP’s objective function, the efficiency of algorithms for solving the BTSP depends heavily on determining correctly the largest and smallest edge costs in the tour. In the proposed branch-and-cut algorithm, we develop several mechanisms based on local cutting planes, edge elimination, and variable fixing to locate those edge costs more precisely. Other critical ingredients in our method are algorithms for initializing lower and upper bounds on the optimal value of the BTSP, which serve as warm starts for the branch-and-cut algorithm. Experiments on the same testbed of TSPLIB instances show that our algorithm can solve 63 out of 65 instances to proven optimality.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139573914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The prediction model of water level in front of the check gate of the LSTM neural network based on AIW-CLPSO","authors":"Linqing Gao, Dengzhe Ha, Litao Ma, Jiqiang Chen","doi":"10.1007/s10878-023-01101-x","DOIUrl":"https://doi.org/10.1007/s10878-023-01101-x","url":null,"abstract":"<p>To solve the problem of predicting water level in front of check gate under different time scales, a different time scale prediction model with a long short term memory (LSTM) neural network based on adaptive inertia weight comprehensive learning particle swarm optimization (AIW-CLPSO) is proposed. The AIW and CLPSO are adopted to improve the global optimization ability and convergence velocity of particle swarm optimization in the proposed model. The model was applied to the water level prediction in front of the Chaohu Lake check gate. The example of the water level prediction in front of the Chaohu Lake check gate shows that the proposed model predicts the trend of water level fluctuation better than LSTM with high accuracy of Nash coefficient up to 0.9851 and root mean square error up to 0.0273 m. The optimized algorithm can obtain the optimal parameters of the LSTM neural network, overcome the limitations of the traditional LSTM neural network in parameter selection and inaccurate prediction, and maintain good prediction results in the predicting water level in front of the check gate at different time scales.This study can provide important reference for water level prediction, scheduling warning, water resources scheduling decision and intelligent gate control in long distance water transfer projects.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139573909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrating supplier selection decisions into an inventory location problem for designing the supply chain network","authors":"","doi":"10.1007/s10878-023-01100-y","DOIUrl":"https://doi.org/10.1007/s10878-023-01100-y","url":null,"abstract":"<h3>Abstract</h3> <p>This paper proposes a novel Inventory-Location problem that integrates supplier selection decisions to design a three-echelon supply chain network, under a continuous (<em>s</em>,<em>Q</em>) inventory control policy at the warehouses. In this problem, a set of warehouses must be selected within a set of potential locations to serve several customers or demand zones, additionally involving the selection of the suppliers for fulfilling incoming orders from the located warehouses. The optimal solution must be determined while minimizing total system costs including supplier selection, transportation (i.e., suppliers-warehouses and warehouses-customers), inventory (i.e., cycle and safety stock), and warehouse location costs. A key element of the problem is the consideration of variable lead-times for the warehouses, which are dependent on the selection of the supplier that serve them, thus increasing model complexity. Accordingly, an efficient algorithm based on the Generalized Benders Decomposition is developed and implemented to solve the proposed Mixed Integer, Nonlinear, Nonconvex, Programming Model. The proposed solution approach relies on a convenient model formulation and decomposition that yields a Mixed Integer Linear master problem and a continuous, convex subproblem. A wide set of medium-sized synthetic instances are optimally solved in affordable times, denoting the efficiency and effectiveness of the proposed model along with the proposed solution approach. Significant scientific and managerial insights are provided and discussed.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139544068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Concentration behavior: 50 percent of h-extra edge connectivity of pentanary n-cube with exponential faulty edges","authors":"Tengteng Liang, Mingzu Zhang, Sufang Liu","doi":"10.1007/s10878-023-01098-3","DOIUrl":"https://doi.org/10.1007/s10878-023-01098-3","url":null,"abstract":"<p>Edge disjoint paths have a closed relationship with edge connectivity and are anticipated to garner increased attention in the study of the reliability and edge fault tolerance of a readily scalable interconnection network. Note that this interconnection network is always modeled as a connected graph <i>G</i>. The minimum of some of modified edge-cuts of a connected graph <i>G</i>, also known as the <i>h</i>-extra edge-connectivity of a graph <i>G</i> (<span>(lambda _{h}(G))</span>), is defined as the maximum number of the edge disjoint paths connecting any two disjoint connected subgraphs with <i>h</i> vertices in the graph <i>G</i>. From the perspective of edge-cut, the smallest cardinality of a collection of edges, whose removal divides the whole network into several connected subnetworks having at least <i>h</i> vertices, is the <i>h</i>-extra edge-connectivity of the underlying topological architecture of an interconnection network <i>G</i>. This paper demonstrates that the <i>h</i>-extra edge-connectivity of the pentanary <i>n</i>-cube (<span>(lambda _{h}(K_{5}^{n}))</span>) appears a concentration behavior for around 50 percent of <span>(hle lfloor 5^{n}/2rfloor )</span> as <i>n</i> approaches infinity. Let <span>(e=1)</span> for <i>n</i> is even and <span>(e=0)</span> for <i>n</i> is odd. It mainly concentrates on the value <span>([4g(lceil frac{n}{2}rceil -r)-g(g-1)]5^{lfloor frac{n}{2}rfloor +r})</span> for <span>(g5^{lfloor frac{n}{2}rfloor +r}-lfloor frac{[(g-1)^{2}+1]5^{2r+e}}{3}rfloor le hle g5^{lfloor frac{n}{2}rfloor +r})</span>, where <span>(r=1, 2,cdots , lceil frac{n}{2}rceil -2)</span>, <span>(gin {1, 2,3,4})</span>; <span>(r=lceil frac{n}{2}rceil -1)</span>, <span>(gin {1,2})</span>. Furthermore, it is shown that the above upper bound and lower bound of <i>h</i> are sharp.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139544063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Alon–Tarsi number of semi-strong product of graphs","authors":"Lin Niu, Xiangwen Li","doi":"10.1007/s10878-023-01099-2","DOIUrl":"https://doi.org/10.1007/s10878-023-01099-2","url":null,"abstract":"<p>The Alon–Tarsi number was defined by Jensen and Toft (Graph coloring problems, Wiley, New York, 1995). The <i>Alon–Tarsi</i> number <i>AT</i>(<i>G</i>) of a graph <i>G</i> is the smallest integer <i>k</i> such that <i>G</i> has an orientation <i>D</i> with maximum outdegree <span>(k-1)</span> and the number of even circulation is not equal to that of odd circulations in <i>D</i>. It is known that <span>(chi (G)le chi _l(G)le AT(G))</span> for any graph <i>G</i>, where <span>(chi (G))</span> and <span>(chi _l(G))</span> are the chromatic number and the list chromatic number of <i>G</i>. Denote by <span>(H_1 square H_2)</span> and <span>(H_1bowtie H_2)</span> the Cartesian product and the semi-strong product of two graphs <span>(H_1)</span> and <span>(H_2)</span>, respectively. Kaul and Mudrock (Electron J Combin 26(1):P1.3, 2019) proved that <span>(AT(C_{2k+1}square P_n)=3)</span>. Li, Shao, Petrov and Gordeev (Eur J Combin 103697, 2023) proved that <span>(AT(C_nsquare C_{2k})=3)</span> and <span>(AT(C_{2m+1}square C_{2n+1})=4)</span>. Petrov and Gordeev (Mosc. J. Comb. Number Theory 10(4):271–279, 2022) proved that <span>(AT(K_nsquare C_{2k})=n)</span>. Note that the semi-strong product is noncommutative. In this paper, we determine <span>(AT(P_m bowtie P_n))</span>, <span>(AT(C_m bowtie C_{2n}))</span>, <span>(AT(C_m bowtie P_n))</span> and <span>(AT(P_m bowtie C_{n}))</span>. We also prove that <span>(5le AT(C_m bowtie C_{2n+1})le 6)</span>.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139101348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal investment decision for photovoltaic projects in China: a real options method","authors":"Xing Zhu, Baoyu Liao","doi":"10.1007/s10878-023-01096-5","DOIUrl":"https://doi.org/10.1007/s10878-023-01096-5","url":null,"abstract":"<p>In an uncertain environment, it is important to investigate whether to postpone, abandon or immediately invest in photovoltaic (PV) projects. This paper applies a real options model to explore the optimal investment decision for investors and the government’s optimal incentive strategy in China’s distributed PV market. The uncertainties of feed-in tariffs (FIT) and investment costs are included in this study as critical factors affecting the options value of PV projects. Multiple scenarios are designed from different dimensions, including various subsidy durations, different resource areas, and distinct regulatory policies. The results show that not only the current FIT and investment cost affect the investment choice, but also the potential change trend of FIT and investment cost affect the investor’s preference. The results also reveal that appropriate FIT regulation can effectively induce investors who abandon investment to choose to delay investment, and significantly shorten the delay time. These conclusions can provide valuable insights for investors to optimize investment decisions.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Capacity decisions and revenue sharing in a telemedicine healthcare system","authors":"Liangliang Sun, Miao Yu, Fenghao Wang","doi":"10.1007/s10878-023-01095-6","DOIUrl":"https://doi.org/10.1007/s10878-023-01095-6","url":null,"abstract":"<p>This paper studies the operations of a telemedicine service system consisting of independent hospitals [general hospital (GH) and telemedicine firm (TF)]. Through the healthcare alliance, the GH and the TF collaborate in capacity decisions and revenue sharing, and establish a green channel to refer patients. We adopt a two-stage game model to study a revenue sharing scheme of the telemedicine healthcare alliance. In the first-stage the game, the GH and the TF negotiate a revenue-sharing ratio to distribute the revenue of the referred patients. In the second stage game, given the profit-sharing ratio, GH makes capacity allocation decisions, and TF determines its own price to maximize its own revenue. Results show that the revenue sharing scheme can increase profits and promote collaboration between GH and TF. When a large number of mild patients arrive at the GH, the GH tends to participate in the alliance. For the TF, high prices do not always yield high profit under the comprehensive influence of the alliance.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methods for determining cycles of a specific length in undirected graphs with edge weights","authors":"R. Lewis, P. Corcoran, A. Gagarin","doi":"10.1007/s10878-023-01091-w","DOIUrl":"https://doi.org/10.1007/s10878-023-01091-w","url":null,"abstract":"<p>In this paper, we consider the <span>({{mathcal{N}mathcal{P}}})</span>-hard problem of determining fixed-length cycles in undirected edge-weighted graphs. Two solution methods are proposed, one based on integer programming (IP) and one that uses bespoke local search operators. These methods are executed under a common algorithmic framework that seeks to partition problem instances into a series of smaller sub-problems. Large-scale empirical tests indicate that the local search algorithm is generally preferable to IP, even with short run times. However, it can still produce suboptimal solutions, even with relatively small graphs.\u0000</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138085647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Algorithmic and complexity aspects of problems related to total restrained domination for graphs","authors":"Yu Yang, Cai-Xia Wang, Shou-Jun Xu","doi":"10.1007/s10878-023-01090-x","DOIUrl":"https://doi.org/10.1007/s10878-023-01090-x","url":null,"abstract":"<p>Let <i>G</i> be a graph with vertex set <i>V</i> and a subset <span>(Dsubseteq V)</span>. <i>D</i> is a <i>total dominating set</i> of <i>G</i> if every vertex in <i>V</i> is adjacent to a vertex in <i>D</i>. <i>D</i> is a <i>restrained dominating set</i> of <i>G</i> if every vertex in <span>(Vsetminus D)</span> is adjacent to a vertex in <i>D</i> and another vertex in <span>(Vsetminus D)</span>. <i>D</i> is a <i>total restrained dominating set</i> if <i>D</i> is both a total dominating set and a restrained dominating set. The minimum cardinality of total dominating sets (resp. restrained dominating sets, total restrained dominating sets) of <i>G</i> is called the <i>total domination number</i> (resp. <i>restrained domination number</i>, <i>total restrained domination number</i>) of <i>G</i>, denoted by <span>(gamma _{t}(G))</span> (resp. <span>(gamma _{r}(G))</span>, <span>(gamma _{tr}(G))</span>). The MINIMUM TOTAL RESTRAINED DOMINATION (MTRD) problem for a graph <i>G</i> is to find a total restrained dominating set of minimum cardinality of <i>G</i>. The TOTAL RESTRAINED DOMINATION DECISION (TRDD) problem is the decision version of the MTRD problem. In this paper, firstly, we show that the TRDD problem is NP-complete for undirected path graphs, circle graphs, S-CB graphs and C-CB graphs, respectively, and that, for a S-CB graph or C-CB graph with <i>n</i> vertices, the MTRD problem cannot be approximated within a factor of <span>((1-epsilon )textrm{ln} n)</span> for any <span>(epsilon &gt;0)</span> unless <span>(NPsubseteq DTIME(n^{O(textrm{loglog}n)}))</span>. Secondly, for a graph <i>G</i>, we prove that the problem of deciding whether <span>(gamma _{r}(G) =gamma _{tr}(G))</span> is NP-hard even when <i>G</i> is restricted to planar graphs with maximum degree at most 4, and that the problem of deciding whether <span>(gamma _{t}(G) =gamma _{tr}(G))</span> is NP-hard even when <i>G</i> is restricted to planar bipartite graphs with maximum degree at most 5. Thirdly, we show that the MTRD problem is APX-complete for bipartite graphs with maximum degree at most 4. Finally, we design a linear-time algorithm for solving the MTRD problem for generalized series–parallel graphs.</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138293508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bounding the total forcing number of graphs","authors":"Shengjin Ji, Mengya He, Guang Li, Yingui Pan, Wenqian Zhang","doi":"10.1007/s10878-023-01089-4","DOIUrl":"https://doi.org/10.1007/s10878-023-01089-4","url":null,"abstract":"<p>In recent years, a dynamic coloring, named as zero forcing, of the vertices in a graph have attracted many researchers. For a given <i>G</i> and a vertex subset <i>S</i>, assigning each vertex of <i>S</i> black and each vertex of <span>(Vsetminus S)</span> no color, if one vertex <span>(uin S)</span> has a unique neighbor <i>v</i> in <span>(Vsetminus S)</span>, then <i>u</i> forces <i>v</i> to color black. <i>S</i> is called a zero forcing set if <i>S</i> can be expanded to the entire vertex set <i>V</i> by repeating the above forcing process. <i>S</i> is regarded as a total forcing set if the subgraph <i>G</i>[<i>S</i>] satisfies <span>(delta (G[S])ge 1)</span>. The minimum cardinality of a total forcing set in <i>G</i>, denoted by <span>(F_t(G))</span>, is named the total forcing number of <i>G</i>. For a graph <i>G</i>, <i>p</i>(<i>G</i>), <i>q</i>(<i>G</i>) and <span>(phi (G))</span> denote the number of pendant vertices, the number of vertices with degree at least 3 meanwhile having one pendant path and the cyclomatic number of <i>G</i>, respectively. In the paper, by means of the total forcing set of a spanning tree regarding a graph <i>G</i>, we verify that <span>(F_t(G)le p(G)+q(G)+2phi (G))</span>. Furthermore, all graphs achieving the equality are determined.\u0000</p>","PeriodicalId":50231,"journal":{"name":"Journal of Combinatorial Optimization","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138293161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}