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Questions tagged [operations-research]

Operations Research is the application of quantitative techniques to decision making, typically involving mathematical optimization. Problems include dynamic programming, linear programming and Integer programming & discrete optimization.

Operations Research is the application of quantitative techniques to decision making, typically involving mathematical optimization. A problem is modeled as a math formulation, and the solution obtained via a solver. Problems in OR include dynamic programming, linear programming and Integer programming and discrete optimization.

The other names for Operations Research (OR) include Decision Science, Management Science, or Operational Research.

The Wikipedia page on Operations Research. INFORMS, the society for OR practitioners has a lot of relevant information.

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Algorithm for creating tournament timetable based on user costraints

I am running a Tennis Website in behalf of a friend of mine because she's not that really passionate about technology and computers. When we create a tournament subscription page, users and amateur tennis players fill out a form to subscribe to…
Jacquelyn.Marquardt
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CP-SAT: Higher num_search_workers value increases the resolution time

Dears, I'm playing with num_search_workers parameter and I discovered a strange behaviour with or-tool 7.5 on windows. I did the following tests on a 32 core machine and I discovered that 1 thread has the best performances. Do you know why?: start…
stefano guerrieri
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How tell CP-SAT to set decision variables with some preferences?

I have a problem with Boolean decision variables. Customer1Accept (True/False) Customer2Accept (True/False) ... Each customer has a score: Customer1score=100 Customer2score=50 ... Each customer can be marked as good or bad:…
stefano guerrieri
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Approximating longest cycle in a directed graph

Finding the longest cycle (By cycle I mean cycle with no node repitition) in a directed graph is an NP-hard problem, otherwise we can tell if the graph is Hamiltonian or not. My question is: Is there any alpha-approxiamtion polynomial algorithm for…
hola
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Why does this two-line change break this minizinc set-cover program?

The program below (adapted from http://www.hakank.org/minizinc/set_covering4b.mzn ) is a solution to the set-cover problem (example data provided at end of question). This runs correctly. int: num_alternatives; int: num_objects; par set of int:…
Max Power
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What is the general name of this vector sum problem?

Given the USDA nutrient database: n vectors where each dimension is a particular nutrient, find a set S of foods F whose vectors sum to .ge. RDA and .lt. any toxic value. Add various other constraints to the model, e.g., calories, mass. Solve for…
Robert Lane
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Cannot fit Markov model in R

I am doing Markov process for my assignment using R. I already designed my matrix but the problem is I cannot put my matrix into markov object. The error is saying .. Error in validObject(.Object) : invalid class “markovchain” object: 1: Error!…
Aung Pyae
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Ortools setting constraints while solving

I am using CP-SAT solver from ortools https://developers.google.com/optimization/cp/cp_solver I am executing the solver with a callback object solver = cp_model.CpSolver() solution_agg = SolutionCollector(data, self.variables, self.products,…
Trion
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Objective function "fairness" coefficients in Google's Operations Research Tools

I am trying to formulate a maximization problem using Google's OR-Tools package. The basis of the optimization is a Fantasy MLB Auction draft. The problem involves the following constraints: 1) Salary Cap of $260 2) 23 total players 2a) At least…
T.S.
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How to define starting state of queueing model in r simmer?

Here's the standard bank counter problem to illustrate my question: Consider a simple bank with customers arriving at random. Customers are to be served at one of two counters, taking a random time for service at each. Also, assume that waiting…
NandaKishore.Rao
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Capacity constraints in ampl

I am building a model that requires me to factor in the capacity of various vessels and I am not sure how to declare this in ampl. Currently, I have: Cap1: forall {i in I, t in T} x[1,i] * people[1,t] <= 500; where I is the set of routes and T is…
user551043
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Simulated annealing: too slow with poor results

I'm trying to solve, thanks to the simulated annealing method, the following problem : Optimization problem Where I already got the c_i,j,f values stored in a 1D array, so that c_i,j,f <=> c[i + j * n + f * n * n] My simulated annealing function…
Mohamed Bouazza
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Adding a constraint in Linear Programming Optimization using PULP

The following code gives me the best places to go to vacation keeping the costs low : from pulp import * import numpy as np import pandas as pd import re #write a scaper before hand data = pd.read_csv('clymb_adventures.csv') problem_name =…
Neelesh I
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Shift planning with Linear Programming

The Modeling and Solving Linear Programming with R book has a nice example on planning shifts in Sec 3.7. I am unable to solve it with R. Also, I am not clear with the solution provided in the book. Problem A company has a emergency center which is…
cogitoergosum
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Linear Programming: Maximize Machine Utilization

I need some help with a linear programming problem I’m trying to solve. The concept is quite simple, we have a set of machines with pre-booked activities that we cannot move. Now I want to add an additional activity with a given time length…
R.Windblixt
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