Displaying 101 – 120 of 219

Showing per page

Fuzzy termination criteria in Knapsack Problem algorithms.

José Luis Verdegay, Edmundo Vergara-Moreno (2000)

Mathware and Soft Computing

Fuzzy rule based termination criteria are introduced in two conventional and exact algorithms solving Knapsack Problems. As a consequence two new solution algorithms are obtained. These algorithms are heuristic ones with a high performance. The efficiency of the algorithms obtained is illustrated by solving some numerical examples.

Genetic Algorithm Approach for Solving the Task Assignment Problem

Savić, Aleksandar, Tošić, Dušan, Marić, Miroslav, Kratica, Jozef (2008)

Serdica Journal of Computing

This research was partially supported by the Serbian Ministry of Science and Ecology under project 144007. The authors are grateful to Ivana Ljubić for help in testing and to Vladimir Filipović for useful suggestions and comments.In this paper a genetic algorithm (GA) for the task assignment problem (TAP) is considered.An integer representation with standard genetic operators is used. Computational results are presented for instances from the literature, and compared to optimal solutions obtained...

Greedy algorithms for optimal computing of matrix chain products involving square dense and triangular matrices

Faouzi Ben Charrada, Sana Ezouaoui, Zaher Mahjoub (2011)

RAIRO - Operations Research - Recherche Opérationnelle

This paper addresses a combinatorial optimization problem (COP), namely a variant of the (standard) matrix chain product (MCP) problem where the matrices are square and either dense (i.e. full) or lower/upper triangular. Given a matrix chain of length n, we first present a dynamic programming algorithm (DPA) adapted from the well known standard algorithm and having the same O(n3) complexity. We then design and analyse two optimal O(n) greedy algorithms leading in general to different optimal solutions...

Greedy algorithms for optimal computing of matrix chain products involving square dense and triangular matrices

Faouzi Ben Charrada, Sana Ezouaoui, Zaher Mahjoub (2011)

RAIRO - Operations Research

This paper addresses a combinatorial optimization problem (COP), namely a variant of the (standard) matrix chain product (MCP) problem where the matrices are square and either dense (i.e. full) or lower/upper triangular. Given a matrix chain of length n, we first present a dynamic programming algorithm (DPA) adapted from the well known standard algorithm and having the same O(n3) complexity. We then design and analyse two optimal O(n) greedy algorithms leading in general to different optimal solutions...

Hamiltonicity and the 3-Opt procedure for the traveling Salesman problem

Gerard Sierksma (1994)

Applicationes Mathematicae

The 3-Opt procedure deals with interchanging three edges of a tour with three edges not on that tour. For n≥6, the 3-Interchange Graph is a graph on 1/2(n-1)! vertices, corresponding to the hamiltonian tours in K_n; two vertices are adjacent iff the corresponding hamiltonian tours differ in an interchange of 3 edges; i.e. the tours differ in a single 3-Opt step. It is shown that the 3-Interchange Graph is a hamiltonian subgraph of the Symmetric Traveling Salesman Polytope. Upper bounds are derived...

Improved approximation of the general soft-capacitated facility location problem

Laurent Alfandari (2007)

RAIRO - Operations Research

The soft-capacitated facility location problem, where each facility is composed of a variable number of fixed-capacity production units, has been recently studied in several papers, especially in the metric case. In this paper, we only consider the general problem where connection costs do not systematically satisfy the triangle inequality property. We show that an adaptation of the set covering greedy heuristic, where the subproblem is approximately solved by a fully polynomial-time approximation...

Integer programming approaches for minimum stabbing problems

Breno Piva, Cid C. de Souza, Yuri Frota, Luidi Simonetti (2014)

RAIRO - Operations Research - Recherche Opérationnelle

The problem of finding structures with minimum stabbing number has received considerable attention from researchers. Particularly, [10] study the minimum stabbing number of perfect matchings (mspm), spanning trees (msst) and triangulations (mstr) associated to set of points in the plane. The complexity of the mstr remains open whilst the other two are known to be 𝓝𝓟-hard. This paper presents integer programming (ip) formulations for these three problems, that allowed us to...

Integer Programming Formulation of the Bilevel Knapsack Problem

R. Mansi, S. Hanafi, L. Brotcorne (2010)

Mathematical Modelling of Natural Phenomena

The Bilevel Knapsack Problem (BKP) is a hierarchical optimization problem in which the feasible set is determined by the set of optimal solutions of parametric Knapsack Problem. In this paper, we propose two stages exact method for solving the BKP. In the first stage, a dynamic programming algorithm is used to compute the set of reactions of the follower. The second stage consists in solving an integer program reformulation of BKP. We show that the...

Large neighborhood improvements for solving car sequencing problems

Bertrand Estellon, Frédéric Gardi, Karim Nouioua (2006)

RAIRO - Operations Research - Recherche Opérationnelle

The 𝒩 P -hard problem of car sequencing has received a lot of attention these last years. Whereas a direct approach based on integer programming or constraint programming is generally fruitless when the number of vehicles to sequence exceeds the hundred, several heuristics have shown their efficiency. In this paper, very large-scale neighborhood improvement techniques based on integer programming and linear assignment are presented for solving car sequencing problems. The effectiveness of this approach...

Large neighborhood improvements for solving car sequencing problems

Bertrand Estellon, Frédéric Gardi, Karim Nouioua (2007)

RAIRO - Operations Research

The NP-hard problem of car sequencing has received a lot of attention these last years. Whereas a direct approach based on integer programming or constraint programming is generally fruitless when the number of vehicles to sequence exceeds the hundred, several heuristics have shown their efficiency. In this paper, very large-scale neighborhood improvement techniques based on integer programming and linear assignment are presented for solving car sequencing problems. The effectiveness of this approach...

Learnheuristics: hybridizing metaheuristics with machine learning for optimization with dynamic inputs

Laura Calvet, Jésica de Armas, David Masip, Angel A. Juan (2017)

Open Mathematics

This paper reviews the existing literature on the combination of metaheuristics with machine learning methods and then introduces the concept of learnheuristics, a novel type of hybrid algorithms. Learnheuristics can be used to solve combinatorial optimization problems with dynamic inputs (COPDIs). In these COPDIs, the problem inputs (elements either located in the objective function or in the constraints set) are not fixed in advance as usual. On the contrary, they might vary in a predictable (non-random)...

Currently displaying 101 – 120 of 219