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1500 questions
11
votes
2 answers
How to quantify the "griddiness" of a set of points?
We're working on a facility location problem in which it is desirable for the facilities to be laid out as close as possible to a grid. In our problem, a lattice is overlaid on the region, and the centers of the resulting cells are potential…
LarrySnyder610
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11
votes
1 answer
Which advantages do the manuscript repositories for our community have?
The question here arises from the fact that we currently have two options:
Optimization Online
ArXiv Optimization and control
Which advantages does each one of them (and others if not included) provide? OO is provided by the Mathematical…
David Bernal
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11
votes
2 answers
Valid Inequalities and Strong Inequalities
Consider the following mixed-integer set:
\begin{equation}
P(A, b ; S) \stackrel{\text { def }}{=}\left\{x \in \mathbb{R}^{n} : A x \leq b, x_{j} \in \mathbb{Z} \text { for } j \in S\right\}
\end{equation}
where $A$ is a real $m \times n$ matrix $,…
A.Omidi
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11
votes
1 answer
How to solve the Cumulative Traveling Salesman Problem using or-tools in python?
The objective of the Cumulative Traveling Salesman Problem (CTSP) is to minimize the sum of arrival times at customers, instead of the total travelling time. This is different than minimizing the overall time of travel. For example, if one has…
Sebastián Quintero
- 111
- 2
11
votes
5 answers
What is the following VRP?
I am researching a Vehicle Routing Problem for a safety insurance company that provides roadside assistance.
The company does not have a depot, as in classical VRP, and has a set of heterogeneous vehicles, as of their use (motorbike used for the…
dimboukosis
- 483
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11
votes
1 answer
Difficulties with Finding a Proper Penalty Value for the Progressive Hedging Algorithm
Recently, I've been working on some two-stage stochastic programming problems. Due to the presence of integer second-stage variables in the model, I've preferred to use the Progressive Hedging Algorithm (PHA). I've implemented my algorithms in GAMS…
Ehsan
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11
votes
1 answer
Simulation in Python
What is the most common package for discrete-event simulation in the OR community?
I have found SimPy package.
Junior MIP
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11
votes
1 answer
Quadratic programming using CPLEX: how to check whether candidate is an extreme point?
I am currently solving an indefinite quadratic program with linear constraints using CPLEX. Moreover, I am trying to determine whether the candidate point CPLEX is feeding my callback function is an extreme point.
I know that a certain $x \in…
DaPurr
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11
votes
2 answers
Decoding a Deep Neural Network as an Analytical Expression for Optimization Purpose
This post is not really about a specific question but rather a topic I am curious about to know more.
We know that when it comes to integrate machine/statistical learning with optimization for the purpose of replacing ideal equations with…
chupa_kabra
- 1,485
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11
votes
1 answer
Modeling an assignment/scheduling problem to minimize total wait
I have an assignment type problem in which there is a set of students, $S$, and a set of training classes $T$. Each training has a fixed start and end day and can accommodate at most 1 student. In addition, a training will give a student credit…
Connor
- 111
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11
votes
1 answer
Expressing a chain of boolean ORs using ILP involving different variables
How can I express a chain of OR operations in an ILP, given that each operand is an inequality between two binary variables? I have asked a similar question here: Chain of Boolean ORs. In that question, I asked specifically about the scenario where…
ephemeral
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11
votes
1 answer
How to relate dual values of valid inequality to the dual values of the original problem?
I have a given formulation that looks like this (just for the constraints):
$$\sum_i \beta_{i,j} \geq \alpha_j,\qquad\forall j$$
$$\alpha_j \geq \sum_i f_{i,j},\qquad\forall j$$
$$\alpha_j \geq 0, f_{i,j} \geq 0$$
In order to reduce the size of my…
dourouc05
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11
votes
1 answer
Algorithm for workforce scheduling for call volumes
I am trying to solve a workforce scheduling and optimization problem.
Available data:
daily level forecasted call volumes,
shift schedules,
resource utilization at the aggregate level,
AHT at daily and hourly level.
I wanted to identify an…
Lalitha Sundar Iyer S
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11
votes
2 answers
Are there examples of spatially explicit MIP problems?
Disclosure: I am an MSc student in economics, but not an expert by any means in OR.
I am trying to model a spatial MIP problem of an invasive species similar to this academic paper, however, my problem differs in that it models the control of a…
GrayLiterature
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10
votes
3 answers
Does the "prize-collecting shortest path problem" exist?
The prize collecting shortest path problem (PCSPP) is a special case of the prize collecting Steiner tree problem (PCSTP) (PCSPP is the PCSTP with only two terminal vertices, namely the source and sink nodes of the PCSPP). I am aware of quite some…
Sune
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