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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 behind standard pulp solver

I'm currently working on an LP optimization problem with and looked into PuLP. I know that PuLPs default solver is: PULP-CBC-CMD. I solved a test problem with this and I'm wondering what kind of algorithm this solver actually uses... it doesnt seem…
learnPyt
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How do I add KKT conditions, dual feasibility constraints into the primal model using Pyomo or Julia?

I've to model certain bilevel problems. The approach is to delete the second level problems by replacing them with their KKT conditions or replacing them with their optimality conditions, such as strong duality ... I wish to do this automatically…
AliRa
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Looping through PuLP nested variables for specific constraints

I have the following constraint: sum of (between p = 0 to p = 2) of X_sap <= A_sa My classes are: # s site_classes = [1, 2] # a age_classes = [1, 2, 3] # p period_classes = [0, 1, 2] age_areas = {1: {'age_range': '0to10', 1: 3000, 2: 8000}, …
dassouki
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Driver scheduling (public transportation): enforcing 30 min break after 4 h of driving time

We're struggling with some aspects of the following problem: a public transportation bus timetable consists of shifts (~ track sections) each with fixed start and end times bus drivers need to be assigned to each of those shifts [constraint in…
movingabout
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Scheduling work shifts using integer programming --- how to formulate feasible constraints?

I'm trying to schedule 30 teaching assistants to cover about 118 hours of office hours. Office hours at different times of day need different coverage (0, 1, 2, or 3 asssistants). People are scheduled on the half hour. I've made an integer linear…
Norman Ramsey
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Which characteristics from commercial Algebraic Modeling Languages are still missing from open source ones?

Which characteristics the main commercial Algebraic Modeling Languages (AML), like GAMS or AMPL, have, that open source AMLs, like Pyomo or JuMP, do not yet have (aside obviously the user base and availability of established models) ?
Antonello
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Coefficients Reduction in Linear Programming lead to incoherent results

I'm a little bit confused about a result that I got after a coefficients reduction on a constraint of a linear programming problem. The problem is: maximize z = x1 + x2 + x3 + x4 + x5 + x6 subject to: 6*x1 + 3*x2 - 5*x3 + 2*x4 + 7*x5 - 4*x6 <=…
Nikaido
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Nurse scheduling model formulation in AMPL

I have been working on a Nurse scheduling problem in AMPL for the following conditions: Total no. of Nurses=20 Total no. of shits= 3 #morning,day,night Planning Horizon 7 days: let's say M T W R F Sa Su Along with following constraints: Max no. of…
Utkarsh Ranjan
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Industrial partitioning problem

We're talking about metal products factory. There is machine which cuts long iron bars to smaller parts which are later used for creating various products. For example, I have requirement to produce bars of following length and quantity: 2 pieces…
m1k4
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Minimise absolute values of weighted sum of numbers

Part of my problem is to minimise the absolute value of the weighted sum of certain numbers. I have to find the weights. Let's say I have a set of numbers A, a1, a2, a3 and a4, such that(a1, a2 > 0), (a3, a4 < 0) Minimum weight is, say, 0.1 (10%),…
Chicoscience
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I need an algorithm that can fit n rectangles of any size in a larger one minimizing its area

I need an algorithm that would take n rectangles of any sizes, and calculate a rectangle big enough to fit them all, minimizing its area so the wasted area is minimum, and also returning the position of all the smaller rectangles within. The…
Petruza
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Find smallest partition of intersecting intervals

Given a set of integer intervals SI = {I1,I2,...,In}, I need to find the smallest partition of SI such that all the intervals of a subset of the partition are intersecting. That is find the smallest P = {Pi : Pi⊂SI } where Pi∩Pj=∅ and such that…
J. M. Aziz
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How can I enumerate all constraints using constraint satisfaction problem

I have an attribute of a product, let's say color. I have the color green and blue. Green is considered better than blue. I have three products A that is green, B that is blue, and C that is green. The question is how can I enumerate all possible…
Leonardo Ribeiro
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How would I go about finding the optimal way to split up an order

I have a problem (that I think I'm over complicating) but for the life of me I can't seem to solve it. I have 2 dataframes. One containing a list of items with quantities that I want to buy. I have another dataframe with a list of suppliers, unit…
Andrew Knoesen
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Scipy.optimize.minimize defining a constraint that limits the number of variables that have non zero values

I am working on an optimization problem, using scipy minimize (method=SLSQP), that uses approx. 700 variables. I am setting minimum and maximum boundaries between 0 and 1. My issue is that the problem requires only 400 variables to have values…
Quipz
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