We examine ways to reformulate integer and mixed integer programs. Typically, but not exclusively, one reformulates so as to obtain stronger linear programming relaxations, and hence better bounds for use in a branch-and-bound based algorithm. First we cover reformulations based on decomposition, such as Lagrangean relaxation, the Dantzig-Wolfe reformulation and the resulting column generation ...

This paper proposes a column generation approach for the Point-Feature Cartographic Label Placement problem (PFCLP). The column generation is based on a Lagrangean relaxation with clusters proposed for problems modeled by conflict graphs. The PFCLP can be represented by a conflict graph where vertices are positions for each label and edges are potential overlaps between labels (vertices). The c...

We present here a Flow/Multicommodity Flow model for Transportation and Production Planning problems. We deal with this model through Lagrangean Relaxation and Hierarchical Decomposition techniques, which involve the resolution of a specific flow with least integral cost sub-problem, and which require the design of some agregation process. We deduce from this analysis several heuristic schemes,...

The problem of optimal synthesis of an integrated water system is addressed in this work, where water using processes and water treatment operations are combined into a single network such that the total cost of designing the network and operating it optimally is globally minimized. The network design has to be feasible and optimal over a given set of scenarios in which different operational co...

In this paper, we present a generic Multistage Stochastic Programming (MSSP) model considering endogenous uncertainty in some of the parameters. To address the issue that the number of non-anticipativity (NA) constraints increases exponentially with the number of uncertain parameters and/or its realizations, we present a new theoretical property that significantly reduces the problem size and c...

In this work, we present an algorithmic framework based on Benders decomposition for the Capacitated p-Cable Trench Problem with Covering. We show that our approach can be applied to most variants of the Cable Trench Problem (CTP) that have been considered in the literature. The proposed algorithm is augmented with a stabilization procedure to accelerate the convergence of the cut loop and with...

The objective of the point-feature cartographic label placement problem (PFCLP) is to give more legibility to an automatic map creation, placing point labels in clear positions. Many researchers consider distinct approaches for PFCLP, such as to obtain the maximum number of labeled points that can be placed without overlapping or to obtain the maximum number of labeled points without overlaps c...

Most existing methods for scheduling are based on centralized or hierarchical decision making using monolithic models. In this study, we investigate a new method based on a distributed and locally autonomous decision structure using the notion of combinatorial auction. In combinatorial auction the bidders demand a combination of dependent objects with a single bid. We show that not only can we ...

MultiProtocol Label Switching (MPLS) technology allows the support of multiple services with different Quality of Service (QoS) requirements in classical IP networks. In an MPLS domain, packet flows belonging to a particular class are classified in the same Forward Equivalence Class (FEC). Based on different FECs, each service can be set up in the network through logical networks. Each logical ...

In this paper we introduce the multi-period incremental service facility location problem where the goal is to set a number of new facilities over a finite time horizon so as to cover dynamically the demand of a given set of customers. We prove that the coefficient matrix of the allocation subproblem that results when fixing the set of facilities to open is totally unimodular. This allows to so...