A modified ant colony system for solving the travelling salesman problem with time windows Chi-Bin Cheng, Chun-Pin Mao Mathematical and Computer Modelling, accepted 29 November 2006 Table 1 Applications of ant colonyoptimization (ACO) Problem domain Traveling salesman problem Quadratic assignment problem Scheduling Vehicle routing problem Literature Algorithm year Colorni et al. [1] Dorigo et al. [14] AS AS 1991 1996 Gambardella and Dorigo [15] Ant-Q 1995 Dorigo and Gambardella [16] ACS 1997 Bullnheimer et al. [17] ASrank 1999 St¨utzle and Hoos [18] MMAS 2000 Gambardella et al. [3] AS-QAP 1999 Maniezzo [4] ANTS-QAP 1999 St¨utzle and Hoos [18] MMAS-QAP 2000 Talbi et al. [19] Parallel Ant Colonies 2001 Solimanpur et al. [20] ACO 2004 Colorni et al. [9] St¨utzle [21] AS-JSP AS-FSP 1994 1998 McMullen [10] ACO 2001 T’kindt et al. [11] ACO 2002 Gravel et al. [12] ACO 2002 Ying and Liao [13] ACS 2004 Shyu et al. [22] ACO 2004 Blum [23] Beam-ACO 2005 Bullnheimer et al. [5] Gambardella et al. [24] AS-VRP MACS-VRPTW 1999 1999 Bell and McMullen [25] ACO 2004 Schoonderwoerd et al. [7] Di Caro and Dorigo [8] ABC AntNet 1996 1998 Gambardella and Dorigo [26] HAS-SOP 2000 Costa and Hertz [6] ANTCOL 1997 Solnon [27] Ant-P-solver 2000 Classification Shelokar et al. [28] ACO classifier system 2004 Clustering Shelokar et al. [29] Kuo et al. [30] ACO Ant k-means 2004 2005 Yang and Kamel [31] Multi-ant colonies 2006 Network routing Sequential ordering Graph colouring Constraint satisfaction References [1] A. Colorni, M. Dorigo, V. Maniezzo, Distributed optimization by ant colonies, in: Proceedings of ECAL91 — European Conference on Artificial Life, Paris, France, 1991, pp. 134–142. [2] W. Gutjahr, A graph-based ant system and its convergence, Future Generation Computer Systems 16 (2000) 873– 888. [3] L.M. Gambardella, E. Taillard, M. Dorigo, Ant colonies for the quadratic assignment problem, Journal of Operational Research Society 50 (1999) 167–176. [4] V. Maniezzo, A. Colorni, The ant system applied to the quadratic assignment problem, IEEE Transactions on Knowledge and Data Engineering 11 (1999) 769–784. [5] B. Bullnheimer, R.F. Hartl, C. Strauss, An improved ant system algorithm for the vehicle routing problem, Annals of Operations Research 89 (1999) 319–334. [6] D. Costa, A. Hertz, Ants can colour graphs, Journal of Operational Research Society 48 (1997) 295–305. [7] R. Schoonderwoerd, O. Holland, J. Bruten, L. Rothkrantz, Ant-based load balancing in telecommunications networks, Adaptive Behavior (1997) 169–207. [8] G. Di Caro, M. Dorigo, AntNet: Distributed stigmergetic control for communications networks, Journal of Artificial Intelligence Research 9 (1998) 317–365. [9] A. Colorni, M. Dorigo, V. Maniezzo, M. Trubian, Ant system for job-shop scheduling, Belgian Journal of Operations Research 34 (1994) 39–53. [10] P.R. McMullen, An ant colony optimization approach to addressing a JIT sequencing problem with multiple objectives, Artificial Intelligence in Engineering 15 (2001) 309–317. [11] V. T’kindt, N. Monmarche, F. Tercinet, D. Laugt, An ant colony optimization algorithm to solve a 2-machine bicriteria flowshop scheduling problem, European Journal of Operational Research 142 (2002) 250–257. [12] M. Gravel, W.L. Price, C. Gagne, Scheduling continuous casting of aluminum using a multiple objective ant colony optimization metaheuristic, European Journal of Operational Research 143 (2002) 218–229. [13] K.-C. Ying, C.-J. Liao, An ant colony system for permutation flow-shop sequencing, Computers and Operations Research 31 (2004) 791–801. [14] M. Dorigo, V. Maniezzo, A. Colorni, The ant system: Optimization by a colony of cooperating agents, IEEE Transactions on Systems, Man and Cybernetics 26 (1996) 29–41. [15] L.M. Gambardella, M. Dorigo, Ant-Q: A reinforcement learning approach to the traveling salesman problem, in: Proceedings of the 12th International Conference on Machine Learning, ML-95, Tahoe City, CA, 9–12 July 1995, pp. 252–260. [16] M. Dorigo, L.M. Gambardella, Ant colony system: A cooperative learning approach to the traveling salesman problem, IEEE Transactions on Evolutionary Computation 1 (1) (1997) 53–66. [17] B. Bullnheimer, R.F. Hartl, C. Strauss, A new rank-based version of the ant system: A computational study, Central European Journal for Operations Research and Economics 7 (1) (1999) 25–38. [18] T. St¨utzle, H.H. Hoos, MAX–MIN ant system, Future Generation Computer Systems 16 (8) (2000) 889–914. [19] E.-G. Talbi, O. Roux, C. Fonlupt, D. Robillard, Parallel ant colonies for the quadratic assignment problem, Future Generation Computer Systems 17 (2001) 441–449. [20] M. Solimanpur, P. Vrat, R. Shankar, Ant colony optimization algorithm to the inter-cell layout problem in cellular manufacturing, European Journal of Operational Research 157 (2004) 592–606. [21] T. St¨utzle, An ant approach to the flow shop problem, in: Proceedings of the 6th European Congress on Intelligent Techniques & Soft Computing, EUFIT’98, Aachen, Germany, 7–10 September 1998, pp. 1560–1564. [22] S.J. Shyu, B.M.T. Lin, P.Y. Lin, Application of ant colony optimization for no-wait flowshop scheduling problem to minimize the total completion time, Computers and Industrial Engineering 47 (2004) 181–193. [23] C. Blum, Beam-ACO — Hybridizing ant colony optimization with beam search: An application to open shop scheduling, Computers and Operations Research 32 (6) (2005) 1565–1591. [24] L.M. Gambardella, ´ E.D. Taillard, G. Agazzi, MACS-VRPTW: A multiple ant colony system for vehicle routing problems with time windows, in: D. Corne, M. Dorigo, F. Glover (Eds.), New Ideas in Optimization, McGraw Hill, London, UK, 1999, pp. 63–76. [25] J.E. Bell, P.R. McMullen, Ant colony optimization techniques for the vehicle routing problem, Advanced Engineering Informatics 18 (2004) 41–48. [26] L.M. Gambardella, M. Dorigo, Ant colony system hybridized with a new local search for the sequential ordering problem, INFORMS Journal on Computing 13 (3) (2000) 237–255. [27] C. Solnon, Solving permutation constraint satisfaction problems with artificial ants, in: Proceedings of the 14th European Conference on Artificial Intelligence, Berlin, Germany, 20–25 August 2000, pp. 118–122. [28] P.S. Shelokar, V.K. Jayaraman, B.D. Kulkarni, An ant colony classifier system: Application to some process engineering problems, Computer and Chemical Engineering 28 (2004) 1577–1584. [29] P.S. Shelokar, V.K. Jayaraman, B.D. Kulkarni, An ant colony approach for clustering, Analytica Chimica ACTA 509 (2004) 187–195. [30] R.J. Kuo, H.S.Wang, T.-L. Hu, S.H. Chou, Application of ant k-means on clustering analysis, Computers and Mathematics with Applications 50 (2005) 1709–1724. [31] Y. Yang, M.S. Kamel, An aggregated clustering approach using multi-ant colonies algorithms, Pattern Recognition 39 (2006) 1278–1289. [32] M. Dorigo, G. Di Caro, L.M. Gambardella, Ant algorithms for discrete optimization, Artificial Life 5 (1999) 137–172. [33] M. Gendreau, A. Hertz, G. Laporte, M. Stan, A generalized insertion heuristic for the traveling salesman problem with time windows, Operations Research 43 (3) (1998) 330–335. [34] M.M. Solomon, Algorithms for the vehicle routing and scheduling problems with time windows constraints, Operations Research 35 (2) (1987) 254–265. [35] D.J. Rosenkrantz, R.E. Stearns, P.M. Lewis, An analysis of several heuristics for the traveling salesman problem, SIAM Journal on Computing 6 (1977) 563–581. [36] J.-Y. Potvin, S. Bengio, The vehicle routing problem with time windows—Part II: Genetic search, INFORMS Journal on Computing 8 (1996) 165–172. A hybrid approach for feature subset selection using neural networks and ant colony optimization Rahul Karthik Sivagaminathan, Sreeram Ramakrishnan Expert Systems with Applications 33 (2007) 49–60 براي. استNP-hard يافتن زيرمجموعه بهينه اي ازويژگيها يك مساله ارزيابي همه وضعيتها از لحاظ محاسباتي،تعداد زيادي ويژگي ممكن نيست بنابراين به روشهاي جستجوي اكتشافي مثل روشهاي روش نمايي شامل روشهايي مثل. ترتيبي و تصادفي نياز است،نمايي شاخه و قيد است كه از يك مجموعه كامل شروع كرده و با استفاده روش ديگر در اين.ويژگيها را حذف مي كند،از استراتژي اول عمق جستجوي پرتوي است كه در آن ويژگيها براساس كيفيت به،مقوله جستجوي پرتوي در هر مرحله.طور نزولي در صف قرار مي گيرند تمام وضعيتهاي ممكن حاصل از افزودن يك زيرمجموعه از ويژگيها .را ارزيابي مي كند 1 ( كه روشهاي مرحله اي همSSA) الگوريتم هاي جستجوي ترتيبي پيچيدگي نسبتا كمتري دارند و از استراتژي تپه،ناميده مي شوند به دليل نقاط.نوردي براي يافتن راه حل بهينه بهره مي برند با شروع از2 به دو دسته انتخاب پيشروي ترتيبيSSA ،شروع مختلف با شروع از مجموعه كامل3يك مجموعه تهي و انتخاب پسروي ترتيبي به طور كلي روشهاي فرااكتشافي به عنوان.ويژگيها تقسيم مي شود .روشهاي جستجوي تصادفي شناخته مي شوند بعدها محققين آن. مطرح شدQAP وTSP اولين بار براي مسايلACO اين.را براي مسايل بهينه سازي گسسته زيادي به كار بردند مختلف مانند بهينه سازي تركيبيNP-hard فرااكتشاف براي مسايل مسايل بهينه سازي تركيبي گسسته.پويا به كار برده شد/ايستا شامل 1 Sequential Search Algorithms Sequential forward selection 3 Sequential backward selection 2 Job shop scheduling (Blum & Sampels, 2002; Colorine, Dorigo, & Maniezzo, 1994) flow shop scheduling (Stu¨ tzle, 1998) open shop scheduling (Blum, 2003) group shop scheduling (Sampels, Blum, Mastrolilli, & Rossi-Doria, 2002) vehicle routing problem (Bullnheimer, Hartl, & Strauss, 1998) sequential ordering (Gambardilla & Dorigo,1997) graph coloring (Costa & Hentz, 1997) shortest common super sequences (Micheal & Middendorf,1999) مسايل بهينه سازي تركيبي پويا شامل مسيريابي در شبكه هاي و بدون (Schoonderwoerd, Holland, Bruten, & Rothkrantz ,1996) اتصال گرا .( استSim & Sun, 2001) اتصال References Almuallim, H., & Dietterich, T. G. (1991). Learning with many irrelevant features. In Proceedings of the ninth national conference on artificial intelligence (AAAI-91) (Vol. 2, pp. 547–552). Anaheim, CA: AAAI Press. Ani, A. Al. (in press). An ant algorithm based approach for feature subset selection. In International Conference on Artificial Intelligence and Machine Learning. Ani, A. Al. (2005). Feature subset selection using ant colony optimization. International Journal of Computational Intelligence, 2(1), 53–58. Blum, C. (2003). An ant-colony optimization algorithm to tackle shop scheduling problems. Tech. report, TR/IRDIA/ 2003-01, IRDIA, Universite’ Libre de Bruxelles, Belgium. Blum, A. L., & Langley, P. (1997). Selection of relevant features and examples in machine learning. Artificial Intelligence, 245–271. Blum, C., & Sampels, M. (2002). Ant colony optimization for fop shop scheduling: A case study on different pheromone representations. In Proceedings of the 2002 congress on evolutionary computing (CEC’02) (pp. 1558). New York: IEEE Press. Bonabeau, E., Dorigo, M., & Theraulaz, G. (1999). From nature to artificial swarm intelligence. New York: Oxford University Press. Boz, O. (2002). Feature subset selection using sorted feature relevance. In The proceedings of ICMLA, international conference of machine learning and applications, Los Angeles, USA (pp. 147–153). Bullnheimer, B., Hartl, R. F., & Strauss, G. (1998). Applying the ant system for the vehicle routing problem. In Meta-heuristics: Advances and trends in local search paradigms for optimizations(pp. 109–120). Cardie, C. (1993). Using decision trees to improve case-based learning. In Proceedings of the tenth international conference on machine learning (pp. 25–32). Los Altos, CA: Morgan Kaufmann Publishers. Caruana, R., & Freitag, D. (1994). Greedy attribute selection. In Proceedings of the eleventh international conference on machine learning (pp. 180– 189). Los Altos, CA: Morgan Kaufmann Publishers. Colorine, A., Dorigo, M., &Maniezzo, V. (1994). Ant system for job shop scheduling. Belgium Journal of Operations Research, Statistics and Computer Science (JORBEL), 34, 39–53. Corne, D., Dorigo, M., & Glover, F. (1999). New ideas in optimization. Maidenhead: McGraw Hill. Costa, D., & Hentz, A. (1997). Ants can color graph. Journal of the Operational Research Society, 48, 295–305. Debuse, J. C. W., &Smith, V. J. R. (1997). Feature subset selection within a simulated annealing data mining algorithm. Journal of Intelligent Information Systems, 9, 57–81. Desai, R., Lin, F. C., & Desai, G. R. (2001). Medical diagnosis with a Kohonen LVQ2 neural network. In Proceedings of the 8th interna- tional conference on neural information processing, Cd-ROM, Shanghai. Devijver, P. A., & Kittler, J. (1982). Pattern recognition: A statistical approach. Englewood Cliffs, NJ: Prentice Hall International. Doak, J. (1992). Intrusion detection: The application offeature selection – A comparison of algorithms, and the application of a wide area network analyzer. Master’s thesis, Department of Computer Science, University of California, Davis. Dorigo, M., Caro, G. D., &Gambardella, L. M. (1999). Ant algorithm for discrete optimization. Artificial Life, 5(2), 137–172. Dorigo, M., & Gambardella, L. M. (1997). Ant colony system: A cooperative learning approach to the traveling salesman problem. IEEE Transaction on Evolutionary Computation, 1(1), 53–66. Gambardilla, L. M., & Dorigo, M. (1997). HAS-SOP: An hybrid ant system for the sequential ordering problem. Tech. report 11-97, Lugano, Switzerland: IDSIA. Gorunescu, F., Gorunescu, M., Darzi, E. El., & Gorunescu, S. (2005). An evolutionary computational approach to probabilistic neural network with application to hepatic cancer diagnosis. In 18th IEEE symposium on computer-based medical systems (CBMS-05) (pp. 461–466). Jensen, R., & Shen, Q. (2003). Finding rough set reducts with ant colony optimization. In Proceedings of the 2003 UK workshop on computational intelligence (pp. 15–22). John, G., Kohavi, R., & Pfleger, K. (1994). Irrelevant features and the subset selection problem. In Machine learning: Proceedings of the eleventh international conference (pp. 121–129). Los Altos, CA: Morgan Kaufmann Publishers. Kira, K., & Rendell, L. A. (1992). The feature selection problem: Traditional methods and a new algorithm. In Proceedings of the 10th national conference on artificial intelligence (pp. 129–134). San Jose, CA: MIT Press. Kulkarni, R. S., Lugosi, G., & Santosh, V. S. (1998). Learning pattern classification – A survey. IEEE Transaction on Information Theory, 44(6), 2178–2206. Kulkarni, R. S., & Vidyasagar, M. (1997). Learning decision rules for pattern classification under a family of probability measures. IEEE Transactions on Information Theory, 43(1), 154–166. Lanzarini, L., & Giusti, D. A. (2000). Pattern recognition in medical images using neural networks. IEEE Transaction on Image and Signal Processing Analysis. Leardi, R., Boggia, R., & Terrile, M. (1992). Genetic algorithms as a strategy for feature selection. Journal of Chemo-metrics, 6, 267–281. Merz, C. J., &Murphy, P. M. (1996). UCI Repository of machine learning databases. Irvine, CA: Department of Information and Computer Science, University of California. Available from http://www.ics.uci.edu/~mlearn/MLRepository.html. Micheal, R., & Middendorf, M. (1999). An ACO algorithm for the shortest common super sequence problem. New ideas in optimization. Maidenhead: McGraw Hill. Narendra, P., & Fukunaga, K. (1977). A branch and bound algorithm for feature subset se lection. IEEE Transactions on Computing, 77(26), 917–922. Pudil, P., Novovicova, J., & Kittler, J. (1994). Floating search methods in feature selection. Pattern Recognition Letters Archive, 15(11), 1119–1125. Punch, W. F., Goodman, E. D., Pei, M., Chia-shun, L., Hovland, P., & Enbody, R. (1993). Further research on feature selection and classification using genetic algorithms. In The proceedings of 5th international conference on genetic algorithm (pp. 557–564). Ripley, B. D., & Hjort, N. L. (1996). Pattern recognition and neural networks. New York: Cambridge University Press. Sampels, M., Blum, C., Mastrolilli, M., & Rossi-Doria, O. (2002). Metaheuristics for group shop scheduling. In The proceedings of seventh international conference on parallel problem solving from nature, PPSN-VII. Lecture notes in computer science, Berlin, Germany (Vol. 2439, pp. 631–640). Schoonderwoerd, R., Holland, O., Bruten, J., & Rothkrantz, L. (1996). Ant-based load balancing in telecommunications networks. Adaptive Behavior, 5(2), 169–207. Schreyer, M., & Raidl, G. R. (2002). Letting ants labeling point features. In Proceedings of the 2002 IEEE congress on evolutionary computation at the IEEE world congress on computational intelligence (pp. 1564– 1569). (2002-11) State of the Ant - Overview of ANTS2002 (SIT Seminar 20-11-2002): Descrete Optimization Group shop scheduling Protein folding Vehicle routing Assembly line balancing Dynamic TSP and QAP Network design Set partitioning Dynamic task allocation Continuous optimization Simulation Robotics Theoretical models of ACO Theoretical ant programming Variations of ACO Anti-pheromone Candidate set Combined GA ant algorithms Others: Web document classification ACOinapplication بيشتر از پوشه Maximum Independent Set Problems Classification Rule Discovery Feature Selection Multi-Label Classification(D:\project\thesis\gecco-2006-chan) Network Routing and Load-Balancing Complex Multi-stage Decision Problems Resource-Constrained Project Scheduling Path Planning for Mobile Robots Generalized Assignment Problem Spatial Cluster Scheduling Problem Mine Detection Application Best Path Planning Constructing Load-Balanced Clusters Loss Minimization in Distribution Networks vehicle routing problem Multiple Travelling Salesman Problem Ship Pipe Route Design in 3D Space )Multicast Routing (IEEE3\article1 )Multiple Knapsack Problem (MKP )Job Shop Scheduling Problem (JSP )Generalized Assignment Problem (GAP )Open shop Scheduling Problem (OSP Car sequencing problem Multiple TSP )Probabilistic TSP (each customer has a given probability of requiring a visit )Set Covering Problem(IEEE3\article9 تعاريف کلي مسايل کالسيک بهينه سازي :QAPانتساب nوسيله 4به nمکان مختلف به نحوي که هزينه هاي جريان کاالها (اجناس) بين وسيله ها کمينه شود. :JSPتعيين ترتيب پردازش تعادي عمليات (که به کارهاي مختلف تقسيم شده اند) روي چند ماشين که ترتيب پردازش عمليات در هر کار ،ثابت است. :MKPانتخاب زيرمجموعه اي از آيتمها با مقدار ماگزيمم (هر آيتم داراي يک مقدار و ميزان نيازمندي هاي آن به منبع است) از يک مجموعه به نحوي که محدوديتهاي بهره وري منابع ،لحاظ گردد. :GAPانتساب هر وظيفه از nوظيفه به دقيقا يکي از mعامل که به هر عامل مي تواند هيچ يا چند وظيفه منتسب شود ،متناسب با قابليتهاي نسبي عاملها. :CSPدر آن هدف قرار دادن ماشينهاي با مدلهاي مختلف در دنباله توليد است به نحوي که جريمه جداسازي ماشينهاي يک مدل ،کمينه شود. :SCPهدف يافتن مجموعه اي از تسهيالت با كمترين هزينه از ميان مجموعه متناهيي از تسهيالت است كه هر گره تقاضا حداقل با يك وسيله پوشش داده شود. D:\project\thesis\aco2004 Facility 4 چاپ كردم 5.3 Significant problems In the following of this section we will present applications of ACO algorithms to some significant combinatorial optimization problems. This is to give the reader an idea of what is involved by the use of an ACO algorithm for a problem: even though the last subsection presents an overview of recent application the list is by no means exhaustive, as it becomes readily evident by searching the web under the keywords “ant colony optimization”. 5.3.1 Sequential ordering problem The first ACO applications were devoted to solve the symmetric and the asymmetric traveling salesman problem. Given a set of cities V = {v1, ... , vn}, a set of 10 edges A = {(i,j) : i,j V} and a cost dij = dji associated with edge (i,j) A, the TSP is the problem of finding a minimal length closed tour that visits each city once. In case dij ? dji for at least one edge (i,j) than the TSP becomes an Asymmetric TSP (ATSP). The first algorithm that applies an ACO based algorithm to a more general version of the ATSP problem is Hybrid Ant System for the Sequential Ordering Problem (HAS-SOP, [34]). HAS-SOP was intended to solve the sequential ordering problem with precedence constraints (SOP). The SOP in an NP-hard combinatorial optimization problem first formulated by Escudero [29] to design heuristics for a production planning system. The SOP mo dels real-world problems like production planning [29], single -vehicle routing problems with pick-up and delivery constraints [64], and transportation problems in flexible manufacturing systems [2]. The SOP can be seen as a general case of both the ATSP and the pick-up and delivery problem [47]. It differs from ATSP because the first and the last nodes are fixed, and in the additional set of precedence constraints on the order in which nodes must be visited. It differs from the pick-up and delivery problem because this is usually based on symmetric TSPs, and because the pick-up and delivery problem includes a set of constraints between nodes with a unique predecessor defined for each node, in contrast to the SOP where multiple precedences can be defined. HAS-SOP combines a constructive phase (ACS-SOP) based on the ACS algorithm [36] with a new local search procedure called SOP-3-exchange. SOP-3exchange is based on a lexicographic search heuristic due to [64], on a new labeling procedure and on a new data structure called don’t push stack inspired by the don’t look bit [5] both introduced by the authors. SOP-3-exchange is the first local search able to handle multiple precedence constraints in constant time. ACS-SOP implements the constructive phase of HAS-SOP but differs from ACS in the way the set of feasible nodes is computed and in the setting of one of the algorithm’s parameters that is made dependent on the problem dimensions. ACS-SOP generates feasible solutions that does not violate the precedence constraints with a computational cost of order O(n2) like the traditional ACS heuristic. A set of experiments based on the TSPLIB data shows that HAS-SOP algorithm is more effective than other existing methods for the SOP. HAS-SOP was compared against the two previous most effective algorithms: a branch-and-cut algorithm [2] that proposed a new class of valid inequalities and Maximum Partial Order/Arbitrary Insertion (MPO/AI), a genetic algorithm by Chen and Smith [17]. To better understand the role of the constructive ACS-SOP phase and the role of the SOP-3-exchange local search MPO/AI was also coupled with the SOP-3exchange local search. Experimental results shows that MPO/AI alone is better than ACS-SOP due to the use of a simple local search embedded in its crossover operator. On the contrary, the combination between constructive phase and local search shows that HAS-SOP is better than both MPO/AI alone and MPO/AI + SOP-3-exchange. This is probably due to the fact that MPO/AI generates solutions that are already optimized and therefore the SOP-3-exchange procedure quickly gets stuck. On the contrary, ACS-SOP solution is a very effective starting point for the SOP-3-exchange local search therefore the HAS-SOP hybridization is very 11 effective. Currently HAS-SOP is the best known method to solve the SOP and was able to improve 14 over 22 best known results in the TSPLIB data set. 5.3.2 Vehicle routing problems A direct extension of the TSP, the first problem AS was applied to, are Vehicle routing problems (VRPs). These are problems where a set of vehicles stationed at a depot has to serve a set of customers before returning to the depot, and the objective is to minimize the number of vehicles used and the total distance traveled by the vehicles. Capacity constraints are imposed on vehicle trips, as well as possibly a number of other constraints deriving from real-world applications, such as time windows, backhauling, rear loading, vehicle objections, maximum tour length, etc. The basic VRP problem is the Capacitated VRP (CVRP): ASrank, the rank-based version of AS, was applied to this problem by Bullnheimer, Hartl and Strauss [7, 8] with good results. These authors used various standard heuristics to improve the quality of VRP solutions and modified the construction of the tabu list considering constraints on the maximum total tour length of a vehicle and on its capacity. Following these results, and the excellent ones obtained by ACS with TSP, SOP and QAP problems, ACS was applied to a VRP version more close to actual logistic practice, called VRPTW. VRPTW is defined as the problem of minimizing time and costs in case a fleet of vehicles has to distribute goods from a depot to a set of customers. The VRPTW minimizes a multiple, hierarchical objective function: the first objective is to minimize the number of tours (or vehicles) and the second objective is to minimize the total travel time. A solution with a lower number of tours is always preferred to a solution with a higher number of tours even if the travel time is higher. This hierarchical objectives VRPTW is very common in the literature and in case problem constraints are very tight (for exa mple when the total capacity of the minimum number of vehicles is very close to the total volume to deliver or when customers time windows are narrow), both objectives can be antagonistic: the minimum travel time solution can include a number of vehicles higher than the solution with minimum number of vehicles (see e.g. Kohl et al., [45]). To adapt ACS to a multiple objectives the Multiple Ant Colony System for the VRPTW (MACS-VRPTW [38]) has been defined. MACS-VRPTW is organized with a hierarchy of artificial ACS colonies designed to hierarchically optimize a multiple objective function: the first ACS colony (ACS-VEI) minimizes the number of vehicles while the second ACS colony (ACS-TIME) minimizes the traveled distances. Both colonies use independent pheromone trails but they collaborate by exchanging information through mutual pheromone updating. In the MACSVRPTW algorithm both objective functions are optimized simultaneously: ACSVEI tries to diminish the number of vehicles searching for a feasible solution with always one vehicle less than the previous feasible solution. 12 0. MACS-VRPTW algorithm 1. {Initialization} Initialize ialize gb the best feasible solution: lowest number of vehicles and shortest travel time. 2. {Main loop} Repeat 2.1 Vehicles #active_vehicles( gb )/* The actual number of used vehicles is computed */ 2.3 Activate ACS-VEI(Vehicles - 1) /* ACS-VEI searches for a feasible solution with always one vehicle less by maximising the num. of visited customers */ 2.4 Activate ACS-TIME(Vehicles) /* ACS-TIME is a traditional ACS colony that minimises the travel time */ While ACS-VEI and ACS-TIME are active Wait for an improved solution y from ACS-VEI or ACSTIME 2.5 gb y if #active_vehicles( gb ) < Vehicles then 2.6 kill ACS-TIME and ACS-VEI End While until a stopping criterion is met ACS-VEI is therefore different from the traditional ACS applied to the TSP. In ACS-VEI the current best solution is the solution (usually unfeasible) with the highest number of visited customers, while in ACS the current best solution is the shortest one. On the contrary, ACS-TIME is a more traditional ACS colony: ACSTIME, optimizes the travel time of the feasible solutions found by ACS-VEI. As in HAS-SOP, ACS-TIME is coupled with a local search procedure that improves the quality of the computed solutions. The local search uses data structure similar to the data structure implemented in HAS-SOP [36] and is based on the exchange of two sub-chains of customers. One of this sub-chain may eventually be empty, implementing a more traditional customer insertion. Experimentally has been shown that the performance of the system increases in case the best solution gb calculated in ACS-TIME is used, in combination with the ACS-VEI best solution ACSVEI , to update the pheromone in ACS-VEI equation (5.7). 13 ACS -VEI ACS - VEI t ij (t) r t ij (t 1) 1 r Ly (i, j) y (5.7) gb gb tij (t) r t ij (t 1) 1r Ly (i, j) y MACS-VRPTW has been experimentally proved to be most effective than the best known algorithms in the field such as the the tabu search of Rochat and Taillard [61], the large neighbourhood search of Shaw [71] and the genetic algorithm of Potvin and Bengio [58]. MACS-VRPTW was also able to improve many results in the Solomon problem set both decreasing the number of vehicle or the travelled time. MACS-VRPTW introduces a new methodology for optimising multiple objective functions. The basic idea is to coordinate the activity of different ant colonies, each of them optimizing a different objective. These colonies work by using independent pheromone trails but they collaborate by exchanging information. This is the first time a multi-objective function minimization problem is solved with a multiple ant colony optimization algorithm. 5.3.3 Quadratic Assignment Problem The quadratic assignment problem (QAP) is the problem of assigning n facilities to n locations so that the assignment cost is minimized, where the cost is defined by a quadratic function. The QAP is considered one of the hardest CO problems, and can be solved to optimality only for small instances. Several ACO applications dealt with the QAP, starting using AS [MC94] and then by means of several of the more advanced versions [54], [66]. The limited effectiveness of AS was in fact improved using a well-tuned local optimizer [53], but several other systems previously introduced were also adapted to the QAP. For example, two efficient techniques are the MMAS-QAP algorithm [71] and HAS-QAP [39]. For the testing of QAP solution algorithms, Taillard [75] proposed to categorize instances into four groups: (i) unstructured, uniform random (ii) unstructured, grid distance, (iii) real-world and (iv) real-world-like. Both MMAS-QAP and HAS-QAP have been applied to problem instances of type i and iii. The performances of these two heuristic approaches are strongly dependent on the type of problem. Comparisons with some of the best heuristics for the QAP have shown that HAS-QAP performs well as far as real-world, irregular and structured problems are concerned. On the other hand, on random, regular and unstructured problems the performance of this technique is less competitive. This problem-dependency was not shown by ANTS, which was also applied to QAP. In order to apply ANTS to QAP (or any other problem), it is necessary to specify the lower bound to use and what is a move in the problem context (step 2.2). The application described in [50] made the following choices. As for the lower bound, since there is currently no lower bound for QAP, which is both tight and efficient to compute, the LBD bound was used, which can be computed in O(n) but which is unfortunately on the average quite far from the optimal solution. As for the moves, it was declared that a move corresponds to the assignment of a facility to a location, thus adding a new component to the partial solution corresponding to the state from which the move originated. Some considerations on the move structure were used to improve the computational effectiveness of the resulting algorithm. ANTS was tested on instances up to n=40 and showed to be effective on all instance types; moreover its direct transposition into an exact branch and bound was also effective when compared to other exact algorithms. 5.3.4 Other problems This section outlines some of the more recent applications of ACO approaches to problems other than those listed in the previous ones. This variety is well represented in the many diverse conference with tracks entirely dedicated to ACO and most notably in ANTS conference series, entirely dedicated to algorithms inspired by the observation of ants' behavior (ANTS'98, ANTS'2000 and ANTS'2002). Many different applications have been presented: from plan merging to routing problems, from driver scheduling to search space sharing, from set covering to nurse scheduling, from graph coloring to dynamic multiple criteria balancing problems. A large part of the relevant literature can be accessed online from [1]. Moreover, several introductory overviews have been published. We refer the reader to [23], [24] and [52] for other overviews on ACO. Among the problems not in the list above, a prominent role is played by the TSP. In fact, TSP has been and in many cases still is the first testbed for ACO variants, and more in general for most combinatorial optimization metaheuristics [68]. It was already on this problem that the limited effectiveness of the first variants emerged, and this fostered the design of improved approaches modifying some algorithm element and possibly hybridizing the framework with greedy local search or with other approaches, such as genetic algorithms or tabu seach [69], [42], [73]. These variants were then applied to other problems, for example MAXMIN ant system was applied to the flow shop problem in [63], a problem then faced also with other ACO modifications [10], whereas in [8] a rank-based approach for the TSP is described or in [14] a so-called best-worst variant. More recently, different authors ([76], [77], [44]) have tackled the TSP with hybrid variants, mainly using tabu search, but also, in the case of large TSP instances, also with genetic evolution and nearest neighbor search, in order to improve both efficiency and efficacy. Moreover, variations of the basic TSP, such as the orienteering problem [49] or the probabilistic TSP where clients have to be visited with a certain probability [4] have also been studied. Scheduling problems provide another common area for testing the effectiveness of ACO algorithms. An ACO approach for the job-shop scheduling is presented in [12], whereas applications to real-world scheduling cases have been recently described in [3] and [62]. More recently, the maturity of the field is showed by the fact that ACO approaches began to be proposed also for problems which are not standard combinatorial optimization testbed, but which are more directly connected to actual practice. For example, the problem of searching and clustering records of large databases is faced by means of ACO in [59], while an algorithm for document clustering is described in [80]. Even more theoretical problems linked to spatial data analysis were tackled with ACO techniques in [74] and [37]. Finally, a recent interesting research branch of ACO, not directly related to combinatorial optimization, is about telecommunication. In fact, the area of packet switching communications appear to be a promising field for ACO-related routing approaches [19, 20]. Whereas a standard optimization version of the frequency assignment problem was described in [51], an application to wavelength allocation was presented in [57], while techniques for path adaptive search are described in [79], [22], [9], [81] and an application to a satellite network in [67]. Moreover, applications directly related to communication Quality of Service (QoS) have been presented in [28], and more recently in [15], while an application which optimizes communication systems with GPS techniques is described in [16]. D:\project\thesis\phd_thesis SCOPs: Stochastic Combinatorial Optimization Problems :در اين تز دو ويژگي برای فرااكتشافات تشخيص داده شده است آنها جايگزين معتبري برای روشهاي كالسيك حقيقي جهت انجام مسايل به عالوه.بهينه سازي تركيبي احتمالي در اندازه واقعي هستند انعطاف پذيرند زيرا آنها مي توانند به سادگي براي حل فرمول . ايستا و پويا تطبيق يابندSCOPs هاي مختلف Acronym PTSP TSPTW VRPSD VRPSDC SCP SSP SDTCP SOPTC Full SCOP name Probabilistic Traveling Salesman Problem Traveling Salesman Problem with Stochastic Time Windows Vehicle Routing Problem with Stochastic Demands Vehicle Routing Problem with Stochastic Demands and Customers Set Covering Problem Shop Scheduling Problem Stochastic Discrete Time-Cost Problem Sequential Ordering Problem with Time Constraint Table 1.1: Explanation of acronyms used to refer to some relevant SCOPs. D:\project\thesis\thesis-abstract D:\project\survey\ A Review of ACO trend basis and model 5 بخش بقيه بعدا ترجمه شوند اولين مقاله اي كه پيدا كردمD:\project\survey\ BC.04-DorDic-NIO99 . قبال چاپ كرده ام. توضيح دارند.9 .2 زير بخش هاي Problem name Authors Year 1991 1995 1996 1997 1997 1994 1997 1998 1998 1998 Main referen ces [16, 21, 22] [23] [19, 20, 24] [48, 49] [6] [41] [27] [50] [40] [39] Traveling salesman Dorigo, Maniezzo & Colorni Gambardella & Dorigo Dorigo & Gambardella StÄutzle & Hoos Bullnheimer, Hartl & Strauss Maniezzo, Colorni & Dorigo Gambardella, Taillard & Dorigo StÄutzle & Hoos Maniezzo & Colorni Maniezzo AS Ant-Q ACS & ACS-3-opt MMAS ASrank AS-QAP HAS-QAP MMAS-QAP AS-QAP ANTS-QAP Bullnheimer, Hartl & Strauss Gambardella, Taillard & Agazzi Schoonderwoerd, Holland, Bruten & Rothkrantz White, Pagurek & Oppacher Di Caro & Dorigo Bonabeau, Henaux, Guerin, Snyers, Kuntz & Theraulaz Di Caro & Dorigo Subramanian, Druschel & Chen Heusse, Gu¶erin, Snyers & Kuntz van der Put & Rothkrantz 1996 1999 1996 [9, 5, 7] [26] [45, 44] AS-VRP HAS-VRP ABC 1998 1998 1998 [55] [14] [4] ASGA AntNet-FS ABC-smart ants 1997 1997 1998 1998 [12, 13, 15] [52] [33] [53, 54] AntNet & AntNet-FA Regular ants CAF ABC-backward Sequential ordering Gambardella & Dorigo 1997 [25] HAS-SOP Graph coloring Shortest common supersequence Costa & Hertz 1997 [10] ANTCOL Michel & Middendorf 1998 [42] AS-SCS Quadratic assignme nt Vehicle routing Connectionoriented network ro uting Connectionless network routing a HAS-QAP b This is an ant algorithm which does not follow all the aspects of the ACO meta-heuristic. is a variant of the original AS-QAP. 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