# Questions tagged [constraint]

For questions related to constraints, i.e. any restriction or relation a set of decision variables has to satisfy.

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### Mixed integer optimization: what if X has to be a rounded multiple of a fixed value? [duplicate]

I am working on a Mosek project. The utility function is to maximize u^{t} x where x is a vector of N There is a tricky constraint: the first 3 items of X must be ...
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### How to force a bounded relationship to "become redundant" or "not needed"?

As an engineer who is currently working with some optimization problem I am currently running into a difficult reformulation problem. Here $a$ is a binary decision variable, $\phi \in [0,1]$ and $d$ ...
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### How to generate random bounded polytope by MATLAB defined by Ax=b, x≥0

How can one create a random bounded polytope in MATLAB, specified by the conditions $‎\lbrace‎x:~ Ax = b,~ x \geq 0‎\rbrace‎$
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### Solve scheduling model using a greedy heurisitc

I have the following scheduling problem. Relatively simple and not very complex (only serves as an example). The indexes are $I$ worker, $T$ days and $J$ shift. The decision variable is $x_{ijt}$, ...
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### Reformulate constraints

I have the following constraints and am wondering whether I can formulate the whole thing more narrowly and with fewer constraints. $x_{itk}$ is binary and $u_{it}, v_{itk}\in [0,1]$. $M$ is a Big-M ...
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### Need Help for building two constraints in MIP model

Really need help for building two constraints with MIP model, I have written the required information and variable information on the diagram below. The way I think of it now is to use two ...
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### Distinguishing between soft and hard constraints

I am currently setting up a nurse rostering model. In it, I have several regulatory constraints, such as limits on working days and so on. Apparently these are considered hard constraints. However, I ...
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### linearizing a constraint involving an absolute function

I would like to know what is the best way to linearize a constraint involving an absolute function. More precisely, imagine I have three binary variables and their relationships is as follows: |x-y| = ...
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### Flow conservation constraints for an Open Vehicle Routing Problem

I'm currently reviewing literature on the Open Vehicle Routing Problem (Open VRP), which characterizes scenarios where trucks do not return to the depot after serving the last customer. In this ...
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### Exception from IBM ILOG CPLEX: CPLEX Error 5002: 'q1' is not convex.->

I am currently solving a scheduling optimization problem regarding the fleet management of AGV/AMR. I always get the same error and I don't know where to start to solve it. Here's the code snippet for ...
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