نتایج جستجو برای: valid inequalities

تعداد نتایج: 121420  

2015
Laura Galli Adam N. Letchford Sebastian J. Miller

The Simple Plant Location Problem is a well-known (andNP-hard) combinatorial optimisation problem, with applications in logistics. We present a new family of valid inequalities for the associated family of polyhedra, and show that it contains an exponentially large number of new facet-defining members. We also present a new procedure, called facility augmentation, which enables one to derive ev...

2006
Gérard Cornuéjols

This tutorial presents a theory of valid inequalities for mixed integer linear sets. It introduces the necessary tools from polyhedral theory and gives a geometric understanding of several classical families of valid inequalities such as lift-and-project cuts, Gomory mixed integer cuts, mixed integer rounding cuts, split cuts and intersection cuts, and it reveals the relationships between these...

2003
R. Montemanni L. M. Gambardella

In this paper we consider the problem of assigning transmission powers to the nodes of a wireless network in such a way that all the nodes of the network are connected and the total power consumption is minimized. A mixed integer programming formulation is presented together with some new valid reinforcing inequalities. Computational results show the effectiveness of the new valid inequalities ...

Journal: :Oper. Res. Lett. 2010
Douglas S. Altner Özlem Ergun Nelson A. Uhan

We study the Maximum Flow Network Interdiction Problem (MFNIP). We present two classes of polynomially separable valid inequalities for Cardinality MFNIP. We also prove the integrality gap of the LP relaxation of Wood’s [19] integer program is not bounded by a constant factor, even when the LP relaxation is strengthened by our valid inequalities. Finally, we provide an approximation-factor-pres...

2005
Alysson M. Costa Jean-François Cordeau Bernard Gendron

Metric inequalities, cutset inequalities and Benders feasibility cuts are three families of valid inequalities that have been widely used in different algorithms for network design problems. This article sheds some light on the interrelations between these three families of inequalities. In particular, we show that cutset inequalities are a subset of the Benders feasibility cuts, and that Bende...

Journal: :Math. Program. 2013
Anja Fischer Christoph Helmberg

In the quadratic traveling salesman problem a cost is associated with any three nodes traversed in succession. This structure arises, e. g., if the succession of two edges represents energetic conformations, a change of direction or a possible change of transportation means. In the symmetric case, costs do not depend on the direction of traversal. We study the polyhedral structure of a lineariz...

Journal: :Discrete Applied Mathematics 2002
Hugues Marchand Alexander Martin Robert Weismantel Laurence A. Wolsey

This survey presents cutting planes that are useful or potentially useful in solving mixed integer programs. Valid inequalities for i) general integer programs, ii) problems with local structure such as knapsack constraints, and iii) problems with 0-1 coefficient matrices, such as set packing, are examined in turn. Finally the use of valid inequalities for classes of problems with structure, su...

Journal: :Operations Research 2010
Lewis Ntaimo

This paper introduces disjunctive decomposition for two-stage mixed 0-1 stochastic integer programs (SIPs) with random recourse. Disjunctive decomposition allows for cutting planes based on disjunctive programming to be generated for each scenario subproblem under a temporal decomposition setting of the SIP problem. A new class of valid inequalities for mixed 0-1 SIP with random recourse is pre...

2010
Ming Zhao Ismael Regis de Farias

We give new facets and valid inequalities for the separable piecewise linear optimization knapsack polytope. We also extend the inequalities to the case in which some of the variables are semi-continuous. In a companion paper [12] we demonstrate the efficiency of the inequalities when used as cuts in a branch-and-cut scheme.

2015
Kai Pan Yongpei Guan

In this paper, we consider the polyhedral structure of the integrated minimum-up/-downtime and ramping polytope, which has broad applications in power generation scheduling prob-lems. The generalized polytope we studied includes minimum-up/-down time, generation ramp-up/-down rate, logical, and generation upper/lower bound constraints. We derive strong validinequalities for this...

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