Papers by Nenad Mladenović
Electronic Notes in Discrete Mathematics, 2012
We are presenting in this volume selected, peer-reviewed, short papers that were presented at the... more We are presenting in this volume selected, peer-reviewed, short papers that were presented at the EURO Mini Conference XXVIII on Variable Neighborhood Search (MEC XXVIII-VNS) which was held during October 4-7, 2012, in Herceg Novi, Montenegro.
... Meta-Heuristics: Advances and Trends in Local Search Paradigms for Optimization. ... Publicat... more ... Meta-Heuristics: Advances and Trends in Local Search Paradigms for Optimization. ... Publication: · Book, Meta-Heuristics: Advances and Trends in Local Search Paradigms for Optimization. ©1999 ISBN:0792383699. 1999 Book. Bibliometrics. ...
Ah strllct : The multi-source w eber problem requ ires locating m IWW fa cili t ies III co nt in ... more Ah strllct : The multi-source w eber problem requ ires locating m IWW fa cili t ies III co nt in uou s s pa ce in order to m inim ize It su m of u-ansportatum costs to n fixed point s or custo mers ....nth kno.....n demands. Several heurisuc methods have been developed LH solve th is problem. Typically, these algnruhms move In de scent directions frnm a specified sta rtillK solut ion until ulocalminimu m is reached. In this paper. we conside r the «ngmel heuristic proposed by Cooper (1963 , 1964 , 19 72 1, wich has no inherent neighbourhood s t ruct u r e. We s ho w how II neighbourhood st ruct u r e can be defined a nd II desce nt-asce nt procedu re employed to e nha nce t he Coo per al gorithm. Computational r esults an' repo rted. I. INTROD UCTION The multi-sou rce W('ber problem. a lso referred to as the unccpacuatod loceuon-allocauon problem , is o ne of the basi c models in continuou s locu t ion theory. The objective is to J.wneraLe opt ima l s it es in co n t inuous sp ace, notably N2, for m new facilit ie s in o r der to m in im ize II su m of transportation custs tu a set of" fixed points or cu stomers with known demands. Si nce ca pacity co ntraints an' no t im posed on the fac ilities. II cu stomer will a lways he se rviced hy the facili ty which is nearest to it. T he rransportatmn cost a ssoClatl"{l Wit h a customer is then ~'l \'l' n by the t ra ve l distance to it s near es t fa cility multiplied by II \\'('ighting fa ctor which is proportional to t he cu stomer 's dema nd rate.
Abst r act: This paper describes a new Tabu search-like technique for solvi ng combinatorial opti... more Abst r act: This paper describes a new Tabu search-like technique for solvi ng combinatorial optimization problems. The cham-interchange move is introduced. • which is an extension of the well-known I-interchange move. Ins tead of Interchanging one solu tion att r ibu te t hat is in the solution .....ith one that is not, four att ributes an' interc hanged. In t hat way the Tabu sea rch recency-based me mory is eas ily obtained, i.e., t he poss ib ility of getti ng out of the local optimu m trap can be ac h ieved without addit io nal efforts. Some location-allocation problema t hat cou ld be solved by t he same chain-interchange algorithm by on ly cha nging the objective function are HEitE'<!. Moreover. most of the problems list ed arc suggested for the first time to be solved by Tabu search me thod (TS). Computer results arc reported. A new local search heuristic C hain-in terchan ge method for sol vi ng co mbinatorial optimization problems is proposed. It could be seen as a Tabu sea rc h me t hod adapted for a large class of problems, as well as an extended interchange heuris t ic. TS was int r oduced by Glove r (1 986) and indepe ndently by Ha nse n (19B6) (u nder t he name Steepest A scent Mildest Descent) as a mete-heurist ic designed to J;l't 11 global optimum to combinatorial opti mization problems. TS belongs to a class of J Wor k on this paper was initia lized during a visit of the first aut hor to L a Laguna University .
Abst r act: This paper describes a new Tabu search-like technique for solvi ng combinatorial opti... more Abst r act: This paper describes a new Tabu search-like technique for solvi ng combinatorial optimization problems . The cham -interchange move is introduced .• which is an extension of the well -known I -interchange move . Ins tead of Interchanging one solu tion att r ibu te t hat is in the solution .....ith one that is not, four att ributes an' interc hanged . In t hat way the Tabu sea rch recency-based me mory is eas ily obtained, i.e., t he poss ib ility of getti ng out of the local optimu m trap can be ac h ieved without addit io nal efforts . Some location-allocation problema t hat cou ld be solved by t he same chain-interchange algorithm by on ly cha nging the objective function are HEitE'<! . Moreover. most of the problems list ed arc suggested for the first time to be solved by Tabu search me thod ( TS). Computer results arc reported.
Abst r act: This paper describes a new Tabu search-like technique for solvi ng combinatorial opti... more Abst r act: This paper describes a new Tabu search-like technique for solvi ng combinatorial optimization problems. The cham-interchange move is introduced. • which is an extension of the well-known I-interchange move. Ins tead of Interchanging one solu tion att r ibu te t hat is in the solution .....ith one that is not, four att ributes an' interc hanged. In t hat way the Tabu sea rch recency-based me mory is eas ily obtained, i.e., t he poss ib ility of getti ng out of the local optimu m trap can be ac h ieved without addit io nal efforts. Some location-allocation problema t hat cou ld be solved by t he same chain-interchange algorithm by on ly cha nging the objective function are HEitE'<!. Moreover. most of the problems list ed arc suggested for the first time to be solved by Tabu search me thod (TS). Computer results arc reported. A new local search heuristic C hain-in terchan ge method for sol vi ng co mbinatorial optimization problems is proposed. It could be seen as a Tabu sea rc h me t hod adapted for a large class of problems, as well as an extended interchange heuris t ic. TS was int r oduced by Glove r (1 986) and indepe ndently by Ha nse n (19B6) (u nder t he name Steepest A scent Mildest Descent) as a mete-heurist ic designed to J;l't 11 global optimum to combinatorial opti mization problems. TS belongs to a class of J Wor k on this paper was initia lized during a visit of the first aut hor to L a Laguna University .
The vertex separation problem belongs to a family of optimization problems in which the objective... more The vertex separation problem belongs to a family of optimization problems in which the objective is to nd the best separator of vertices or edges in a generic graph. This optimization problem is strongly related to other well-known graph problems; such as the Path-Width, the Node Search Number or the Interval Thickness, among others. All of these optimization problems are NP-hard and have practical applications in VLSI (Very Large Scale Integration), computer language compiler design or graph drawing. Up to know, they have been generally tackled with exact approaches, presenting polynomial-time algorithms to obtain the optimal solution for specic types of graphs. However, in spite of their practical applications, these problems have been ignored from a heuristic perspective, as far as we know. In this paper we propose a pure 0-1 optimization model and a metaheuristic algorithm based on the variable neighborhood search methodology for the vertex separation problem on general graphs. Computational results show that small instances can be optimally solved with this optimization model and the proposed metaheuristic is able to nd high-quality solutions with a moderate computing time for large-scale instances.
Many optimization problems are formulated as min-max problems where the objective function consis... more Many optimization problems are formulated as min-max problems where the objective function consist of minimizing a maximum value. In this case, it is usual that many solutions of the problem has associated the same value of the objective function. When this happens it is difficult to determine which solution is more promising to continue the search. In this paper we propose a new variant of the Variable Neighbourhood Search methodology to tackle this kind of problems. The new variant, named Variable Formulation Search, makes use of alternative formulations of the problem to determine which solution is more promising when they have the same value of the objective function in the original formulation. We do that in shaking, local search and neighbourhood change steps of the basic Variable Neighbourhood Search. We apply the new methodology to the Cutwidth Minimization Problem. Computational results show that our proposal outperforms previous algorithms in the state of the art in terms of quality and computing time.
Electronic Notes in Discrete Mathematics, 2015
Yugoslav Journal of Operations Research, 2002
ABSTRACT
The asymmetric distance-constrained vehicle routing problem consists of finding vehicle tours to ... more The asymmetric distance-constrained vehicle routing problem consists of finding vehicle tours to connect all customers with a depot such that the total distance is minimum and the travelled distance by each vehicle is less than or equal to the given maximum value. In order to solve it exactly we develop new tolerance based branching rules within branch and bound method. Since our method is fast but memory consuming, it could stop before optimality is proven. Therefore we introduce the idea of randomness in choosing the node of search tree that will be next chosen. If an optimal solution is not found, we restart our method. In that way we get multi-start with branch-and-bound method. Computational experiments show that with our multi-start branch and bound approach we are able to solve exactly large test instances with up to 1000 customers. keywords: Branch and Bound; Tolerance; Vehicle routing; CPLEX.
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Papers by Nenad Mladenović