Welcome to the OR-Exchange, your site for questions and answers in operations research.

Tagged Questions

3
votes
3answers
84 views

Vehicle Routing Problem With Uncertain Number of Vehicles?

I'm working on modeling a VRP-type problem where drivers not showing up is a problem. I'm wondering if people have done work on this and having trouble finding much (or anything at …
0
votes
1answer
53 views

Taylor-Linearization that eliminates intermediate variables.

This must seem like a really elementary question, so please bear with me. Suppose I have a nonlinear system of equations: f(x) = 0 where x = [ y z u ]'. y = vector of output var …
1
vote
5answers
178 views

Dantzig Wolfe Dual Prices

Hi everyone. Another DW question... First of all, you can see the structure of my problem here: http://www.kreutz.us/images/structure.png (Note: I know Benders decomp would probab …
1
vote
2answers
134 views

Subproblem solutions in Dantzig-Wolfe

Hi everyone I'm solving a problem using DW which has many subproblems (as seen in the drawing here: http://en.wikipedia.org/wiki/Dantzig%E2%80%93Wolfe_decomposition ). In a given …
3
votes
4answers
261 views

Industrial Engg. Vs Operational research

How industrial engineering differs from operational research ? I came across following various which more or less relate to a common idea of making system efficient a) Industrial …
3
votes
6answers
290 views

Performance of LP solvers

Hi Guys, I am working on a LP relaxation of a large scale industrial problem ( over half a million variables and several tenths of thousands constraints ), using coin-or clp. Do y …
2
votes
3answers
133 views

Cutting Planes for Bin Packing

I'm working on a problem that is closely related to one-dimensional bin packing. All of the research that I've found on bin-packing focuses on heuristics, approximation algorithms, …
4
votes
3answers
233 views

Operations Research Interview Questions

What are questions you would ask if you are conducting an interview for hiring a Operations Research Analyst?
3
votes
2answers
116 views

Starting a formulation

What is the best approach to start formulating a model given the project requirements? In other words how do you structure your "FORMULATION" process?
3
votes
3answers
116 views

Runtime of a Mathematical model

Has anyone tried to develop a method to predict run-time of a mathematical model given a solver like CPLEX?
4
votes
2answers
57 views

Serious metrics for mixed features

Hi folks, I am currently developing a data analysis prototype for a set of ~40-dimensional data points and therefore try to map all of them into a metric space. However, my featur …
4
votes
7answers
140 views

What have you used OR for other than your “job”?

I'm looking for answers that is using OR in your daily lives that is outside of your day job. Have you used OR for fun? Did you use it to solve for something around the house, co …
2
votes
4answers
109 views

References for the conjecture: Any regression can be translated into a math model

In a Twitter discussion about symbolic regression (more specific about the genetic programming system Eureqa), siah suggested using LP instead of genetic programming, and stated th …
1
vote
1answer
81 views

What is a free constraint

Hey, When looking through Coin-Or, I found they were referring to a constraint type called "free constraint". For instance here. Does any one know what a free constraint is? Tha …
3
votes
3answers
228 views

How do you decide whether MIP or CP is more appropriate?

What are some guidelines for deciding whether a MIP or CP approach is more appropriate for modeling an optimization problem? Or in what cases should CP be used instead of MIP?