Unanswered Questions
862 questions with no upvoted or accepted answers
7
votes
0
answers
96
views
Calculating robustness of layout plans
We have tried to design a manufacturing cell which will produce specific families of products. We figure out three layout plans for implementation. For practical reasons, we need to calculate the ...
- 5,442
6
votes
0
answers
142
views
What are some recommended Master's degree programs for individuals interested in specializing in the development of MI(L)P solvers?
There are tons of Masters programs across North America and Europe focused on OR/Industrial Engineering.
I am interested especially in solver technology and would be very grateful if someone could ...
- 61
6
votes
0
answers
213
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Benders decomposition for a dense MILP
I am trying to solve a large MILP, but it seems like dense problems can be very difficult for moderns solvers. I tried to solve the problem described below considering only constraints (1) and (2) ...
- 109
6
votes
0
answers
94
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Graph coloring problem while counting cliques
Let $G$ be a graph with a set of nodes $V$ and a set of edges $E$.
Let $G'$ be a graph with the same set of nodes $V$ but a second set of edges $E'$.
For a set of nodes $X\subset V$, we denote $f(X)$ ...
- 5,442
6
votes
0
answers
88
views
Robust Linear Optimization for avoiding diminishing returns
My engineering problem can be formulated as an LP as shown below
\begin{align}
\max_{\mathbf{x}}~~&\mathbf{a}^T\mathbf{x} \\
\mbox{s.t.}~~~&\mathbf{b}^T\mathbf{x} \leq B~~,~~\mathbf{1}^T\...
- 251
6
votes
0
answers
111
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Dual instability, degeneracy, tailing off effect - Which are the causes and which are the effects?
Dual instability, degeneracy, and the tailing off effect are often mentioned together in papers. However, I cannot seem to find a clear explanation on which of these cause the other and vice versa? ...
- 173
6
votes
2
answers
171
views
Complexity of the ellipsoid method in general convex problems
The ellipsoid method is often mentioned in relation to the complexity of solving linear programs.
Is the method however polynomial in the general non-linear convex cases? Preferably I would like a ...
CommunityBot
- 1
6
votes
0
answers
91
views
Issue of Dense columns in the formulation
I'm working on a price-selection model where we need to identify price point for each time-period (could be day/week). Objective of the model is to figure out optimal price-point for each time-point ...
- 984
6
votes
0
answers
226
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Airline revenue management re-solving problem
I am considering a bid prices (shadow price of the capacity constraint) problem (from Chen, L. and Homem-de Mello, T. (2009)., page 14) where the acceptable classes for booking requests for ...
- 165
6
votes
0
answers
95
views
Sample Average Approximation vs. Numerical Integration
In the sense of the calculation of the expected value of objective functions, we have two choices to evaluate the value; 1. Sample Average Approximation (SAA):
$$
\frac{1}{N}\sum_{i=1}^N f(x,\xi^i).
$$...
- 155
6
votes
1
answer
248
views
Which software to use for Voronoi diagrams?
I have recently been looking at some facility location problems and how they change in the presence of the motorway (or highway, freeway) etc. Tried to visualize some observations with the Voronoi ...
6
votes
0
answers
127
views
Water quality component optimization
I have an optimization problem that I'm attempting to tackle. As you can see in the image below, there's a graph network through which water flows. I've drawn out the problem in the image to explain ...
- 5,874
6
votes
0
answers
135
views
Characterization for total dual integrality
A problem I study reduces to whether the polyhedron $P=\{\mathbf{x}\mid A\mathbf{x}=\mathbf{1}, \mathbf{x}\geq0\}$ is integral ($A$ is a matrix with coefficients in $\{0,1\}$). I know that the ...
- 137
6
votes
0
answers
53
views
What are useful plots/statistics/metrics when analyzing the solution sensitivity in multi-objective optimization?
Consider an optimization problem with $n>3$ objectives.
For handling this there exists often two approaches:
a) some weighting of the objectives,
b) fix an order of objectives and then optimize ...
- 5,442
6
votes
0
answers
106
views
Estimating multistop routing costs
In many OR problems, it is sometimes a good idea (or necessary) to relax routing constraints.
An example of this occurs in the classical facility location problem, where a warehouse can send out a ...
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