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1500 questions
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2 answers

How to solve Rogo Puzzle with an extra constraint?

Given a n×m grid with numbered cells and forbidden cells, the objective of the Rogo puzzle is to find a loop of fixed length through the grid such that the sum of the numbers in the cells on the loop is maximized. Some cells should be avoided. ROGO…
Optimization team
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What would be a representative/appropriate name for operations research?

Assuming you have a masters degree in operations research and this masters degree is offered in an economics department of your university. What would be a representative/appropriate name to describe this masters program to a stranger, acquaintance,…
oestersem
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1 answer

Modulo Integer Programming, $m$ equations $n$ variables

I am following 'Application of Number Theory to Numerical Analysis', and there is a section by G.H. Bradley called 'Modulo Optimization Problems and Integer Linear Programming'. There he explains that turns a modulo integer programming problem into…
AyamGorengPedes
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6
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2 answers

Fleet Management: How to allocate vehicles between departments

Assume that I have data about a regular big company (not a salesman problem). data contains of every department's (marketing, finance, production, etc.) vehicle size, GPS track values, duration of using vehicles, etc. I want to optimize the fleet…
maxime
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6
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Strong branching scores when objective function is constant

I have a MILP feasibility problem, so the objective function is constant (0). I have read that strong branching scores measure changes in the objective value. So my question is, what would be the strong branching scores in my case?
Elena
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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\mathbf{x}\leq 1~~,~~\mathbf{x}\geq 0 \end{align} Let…
dineshdileep
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6
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2 answers

Python vs C++ performance on Discrete Optimization

Are there any useful resources to compare the performance of python and c++ languages in algorithms dedicated to solving discrete optimization problems?
Nada.S
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6
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2 answers

How to measure the tightness of MILP models?

Suppose we have a MILP model. How can we say this model is tight or not? How to make it more tight? Any advice or example?
Optimization team
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Use GA for Assignment Problem?

I have a two-objective assignment problem that appears to converge really slowly to a solution. Even if we just have 1 objective that minimizes costs, it appears to be very slow for a worker-task matrix has a size of $500 \times 500$ and using…
Nyxynyx
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Light weight proof of strong duality in linear programming

For teaching purposes, I believe it can be good to use very light-weight proofs of deep results, as it often answers the question "why is it true" better than other types of proofs. By "light-weight proofs" I mean proofs that rely as little as…
Sune
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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? How are they connected? Are there any other…
gmn
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Binary decision variable to indicate whether a continous decision variable is equal to its upper bound

Given a continuous nonnegative decision variable $x\in [0,T]$ bounded by $T$, how can we enforce a relation between $x$ and another binary decision variable $y$ such that when $x$ is equal to its upper bound ($T$), $y$ must be one and otherwise $y$…
A. H
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Linear Programming problem for finding supplier

I have a linear programming problem in front of me that I am searching to solve in R (any package). It seems like an unbalanced assignment problem to me with relaxed constraints on columns (repeated assignment is possible) or more general possibly a…
Patrik
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Help modeling grid placement problem

I'm trying to model a grid placement problem to exercise in OR. The problem is defined as: a grid of some dimension (let's say 500x500) N users that need connection. Every user has: a defined position on the grid a speed value a latency value M…
rsella
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