Showing papers in "Electronic Notes in Discrete Mathematics in 2010"

TL;DR: This paper reviews generic classes of column generation based primal heuristics and introduces diversification based on Limited Discrepancy Search, a so-called “diving” method in which the implementation of the heuristic illustrates the technicalities specific to column generation.

TL;DR: This paper considers the Two-Echelon Vehicle Routing Problem (2E-CVRP), the two-echelon variant of the well known Capacitated Vehicle Routed Problem, where the delivery from one depot to the customers is managed by routing and consolidating freight through intermediate depots, called satellites.

TL;DR: This paper analyzes uncapacitated and capacitated versions of the logit assortment problem, and proposes a branch-and-cut algorithm that is computationally feasible and leads to high-quality solutions.

TL;DR: A mixed-integer linear programming formulation (MILP1), when the bins are identical with the aim of minimizing the number of the used bins, and some special valid inequalities will be presented in order to improve the relaxed lower bound of MILP1.

TL;DR: The aim is to decide the optimal number of check-in gates to open for departing flights, in such a way to balance the operative costs of the service and the passenger waiting time at the terminal.

TL;DR: The Erdős-Gallai Theorem gives the maximum number of edges in a graph without a path of length k, and this result is extended for Berge paths in r-uniform hypergraphs.

TL;DR: A new algorithm for solving the LP relaxation of the precedence constrained knapsack problem and an LP-based heuristic to obtain feasible solutions are presented.

TL;DR: A new result is presented on the design found by rounding the solution of the continuous relaxed problem, an approach which has been applied by several authors: when the goal is to select n out of s experiments, the D-optimal design may be rounded to a design for which the dimension of the observable subspace is within n s of the optimum.

TL;DR: In this paper, exact and heuristic approaches are proposed to solve a dynamic and online problem that appears in CDN management, called the Replica Placement and Request Distribution Problem, which aims to find the best servers to keep the replicas and to handle requests so that the traffic cost in the network is minimized without violating server and QoS constraints.

TL;DR: This article considers the inverse 1-median problem on a tree and on a path and aims to change the vertex weights at minimum total cost with respect to given modification bounds such that a prespecified vertex becomes 1-Median.

TL;DR: An iterative local search is developed to deal with a location routing problem with multiple capacitated depots by considering the decisions of location and routing simultaneously and intensifying the solution space with the local search.

TL;DR: This work proposes using a version of the Traveling Salesman Problem that minimizes both distance and direction change angles to determine the tour specifying the order in which the points should be visited, and applies a shortest path algorithm on a discretized search space.

TL;DR: A general lower bound for MSCP is proposed based on extraction of specific partial graphs using some decomposition into cliques and the experimental results show that this approach improves the results for most literature instances.

TL;DR: This work proposes to include mutiple crossover and mutation operators with a dynamic selection scheme into a multiobjective genetic algorithm in order to choose the best crossover operator to be used at any given time and shows synergy effects among used crossovers.

TL;DR: This paper uses tabu search to solve the sum coloring problem and shows significative improvements on some chromatic sum bounds on instances extracted from the second DIMACS challenge.

TL;DR: The empirical performance of a threat-based online algorithm is evaluated and it is compared to a reservation price algorithm, an average price algorithm and to buy-and-hold, which dominates all other investigated algorithms.

TL;DR: A simple model with intersting properties that allows to use traditional algorithms with little modifications on the fastest path problem and offers multiple suggestions adapted to variety of user preferences is proposed.

TL;DR: A new method for finding an initial feasible solution for Mixed integer programs that combines ideas of Variable neighborhood branching and Feasibility pump heuristics is proposed, which manages to obtain better initial objective function values than CPLEX.

TL;DR: This work considers an uncapacitated p-median system that is subject to external manmade or natural disruptions and formulate the problem of protecting against the worst-case losses when taking into account facility recovery issues, and applies two exact decomposition methods.

TL;DR: A method for the automatic detection of formulation symmetries in MINLP instances is described and a software implementation of this method is used to conjecture the group structure of the problem asymmetries of packing equal circles in a square.

TL;DR: This work considers Simultaneous Balancing and Scheduling of Flexible Mixed Model Assembly Lines with Sequence-Dependent Setup Times (SBSFMMAL-SDST) and proposes alternate Mixed Integer Programming and Constraint Programming formulations.

TL;DR: A class of linear inequalities is presented that, together with the well-known McCormick inequalities, defines the convex hull of M_2, the bounded, nonconvex set of a product of n variables for any n ≥ 2.

TL;DR: This paper proposes a Bicriteria Genetic Algorithm approach to solve the BSP with the two conflicting objectives, minimizing the transportation cost and the total travel time.

TL;DR: The guaranteed service model (GSM) computes optimal order-points in multi-echelon inventory control under the assumptions that delivery times can be guaranteed and the demand is bounded and the new stochastic guaranteed servicemodel (SGSM) with Recourse covers also scenarios that violate these assumptions.

TL;DR: This paper focuses on the case where the travel time between two cities depends not only on the distance between them, but also on the position of the arc in the tour.

TL;DR: This note addresses a relaxation for 0-1 ILPs that explicitly takes all variable bound constraints into account, and introduces the concept of knapsack closure as a tightening of the classical Chvatal-Gomory (CG) closure.

TL;DR: New hybrid heuristics for the 0-1 mixed integer programming problem are proposed, based on the variable neighbourhood decomposition search principle and on exploiting information obtained from a series of relaxations, comparable with the current state-of-the-artHeuristics on a set of large scale instances.

TL;DR: A new genetic algorithm inspired by the philosophy of dynamic programming, where the chromosome and the population lengths are varied from one iteration to another, is proposed.

TL;DR: A survey on recent results about the Maximum Internal Spanning Tree problem including different approaches such as exact exponential algorithms, fixed parameter tractability, and approximation algorithms is given.

TL;DR: New formulations to a well-known telecommunication problem: routing several commodities subject to multiple delay constraints using Disjunctive Programming to derive tight convex formulations of Mixed Integer NonLinear Programs featuring “on/off" constraints.