Mixed integer programs (MIPs) are commonly solved with branch and bound algorithms based on linea... more Mixed integer programs (MIPs) are commonly solved with branch and bound algorithms based on linear programming. The success and the speed of the algorithm strongly depends on the strategy used to se lect the branching variables. Today's state-of-the-art strategy is called pseudocost branching and uses information of previous branchings to determine the current branching. We propose a modification of pseudocost
Starting with the description of the Traveling Salesmen Problem formulation as given by van Vyve ... more Starting with the description of the Traveling Salesmen Problem formulation as given by van Vyve and Wolsey in the article “Approximate extended formulations”, we investigate the effects of small variations onto the performance of contemporary mixed integer programming solvers. We will show that even minor changes in the formulation of the model can result in performance difference of more
This article introduces constraint integer programming (CIP), which is a novel way to combine con... more This article introduces constraint integer programming (CIP), which is a novel way to combine constraint programming (CP) and mixed integer programming (MIP) methodologies. CIP is a generalization of MIP that supports the notion of general constraints as in CP. This ap- proach is supported by the CIP framework SCIP, which also integrates techniques for solving satisability problems. SCIP is available
We present publicly available data sets related to research on wireless networks. The sce- narios... more We present publicly available data sets related to research on wireless networks. The sce- narios contain a wide range of data and are detailed in all aspects. To our knowledge, this is the most realistic, comprehensive, and detailed public data collection on mobile networking. We indicate example uses of this data collection in applications related to UMTS.
The UMTS radio network planning problem poses the challenge of de- signing a cost-eectiv e networ... more The UMTS radio network planning problem poses the challenge of de- signing a cost-eectiv e network that provides users with sucien t coverage and capacity. We describe an optimization model for this problem that is based on comprehensive planning data of the EU project Momentum. We present heuristic mathematical methods for this realistic model, including computational results.
... Solver William Cook1,* , Thorsten Koch2, Daniel E. Steffy1,* , and Kati Wolter2,** 1 School o... more ... Solver William Cook1,* , Thorsten Koch2, Daniel E. Steffy1,* , and Kati Wolter2,** 1 School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA bico@isye.gatech.edu, desteffy@gatech.edu 2 Zuse Institute Berlin, Germany {koch,wolter}@ ...
Mixed integer programs are commonly,solved with linear programming based branch-and-bound algorit... more Mixed integer programs are commonly,solved with linear programming based branch-and-bound algorithms. The success of the algorithm strongly depends on the strategy used to select the variable to branch on. We present a new generalization called reliability branching of today’s state-of-the-art strong branching and pseudocost branching branching strategies for linear programming,based branch-and-bound algorithms. After reviewing commonly,used branching strategies and performing
... 1991; Khan and Sait 2004) use a physical force scheme to model the placement problem as a con... more ... 1991; Khan and Sait 2004) use a physical force scheme to model the placement problem as a convex optimization problem. ... The approach usually taken in practice is to choose the terminal to use from each group before the routing. ...
Mixed integer programs (MIPs) are commonly solved with branch and bound algorithms based on linea... more Mixed integer programs (MIPs) are commonly solved with branch and bound algorithms based on linear programming. The success and the speed of the algorithm strongly depends on the strategy used to se lect the branching variables. Today's state-of-the-art strategy is called pseudocost branching and uses information of previous branchings to determine the current branching. We propose a modification of pseudocost
Starting with the description of the Traveling Salesmen Problem formulation as given by van Vyve ... more Starting with the description of the Traveling Salesmen Problem formulation as given by van Vyve and Wolsey in the article “Approximate extended formulations”, we investigate the effects of small variations onto the performance of contemporary mixed integer programming solvers. We will show that even minor changes in the formulation of the model can result in performance difference of more
This article introduces constraint integer programming (CIP), which is a novel way to combine con... more This article introduces constraint integer programming (CIP), which is a novel way to combine constraint programming (CP) and mixed integer programming (MIP) methodologies. CIP is a generalization of MIP that supports the notion of general constraints as in CP. This ap- proach is supported by the CIP framework SCIP, which also integrates techniques for solving satisability problems. SCIP is available
We present publicly available data sets related to research on wireless networks. The sce- narios... more We present publicly available data sets related to research on wireless networks. The sce- narios contain a wide range of data and are detailed in all aspects. To our knowledge, this is the most realistic, comprehensive, and detailed public data collection on mobile networking. We indicate example uses of this data collection in applications related to UMTS.
The UMTS radio network planning problem poses the challenge of de- signing a cost-eectiv e networ... more The UMTS radio network planning problem poses the challenge of de- signing a cost-eectiv e network that provides users with sucien t coverage and capacity. We describe an optimization model for this problem that is based on comprehensive planning data of the EU project Momentum. We present heuristic mathematical methods for this realistic model, including computational results.
... Solver William Cook1,* , Thorsten Koch2, Daniel E. Steffy1,* , and Kati Wolter2,** 1 School o... more ... Solver William Cook1,* , Thorsten Koch2, Daniel E. Steffy1,* , and Kati Wolter2,** 1 School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA bico@isye.gatech.edu, desteffy@gatech.edu 2 Zuse Institute Berlin, Germany {koch,wolter}@ ...
Mixed integer programs are commonly,solved with linear programming based branch-and-bound algorit... more Mixed integer programs are commonly,solved with linear programming based branch-and-bound algorithms. The success of the algorithm strongly depends on the strategy used to select the variable to branch on. We present a new generalization called reliability branching of today’s state-of-the-art strong branching and pseudocost branching branching strategies for linear programming,based branch-and-bound algorithms. After reviewing commonly,used branching strategies and performing
... 1991; Khan and Sait 2004) use a physical force scheme to model the placement problem as a con... more ... 1991; Khan and Sait 2004) use a physical force scheme to model the placement problem as a convex optimization problem. ... The approach usually taken in practice is to choose the terminal to use from each group before the routing. ...
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Papers by Thorsten Koch