# Questions tagged [modeling]

For questions related to the process of converting a real-world problem into a mathematical model. Can include questions related to linearization, logical constraints, tightness of formulations, and so on.

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### Calculus problem - How to determine the extremes locus and increasing/decreasing region of the plan [closed]

Determine, without solving the equation, the locus of the extremes of the solution of y: $$y' = ty - 1$$ In which region of the plan are they increasing, decreasing ?
390 views

### How to reduce the risk of wrong modelling in OR industry projects?

In my experience many OR Industry projects contains at least one person with background in OR (who is not familiar with the technical background) and at least one person from industry with the ...
124 views

### Switching of decision variables to be equal to a certain decision variable according to a binary (indicator) variable

I would like to seek some advice on modeling the following: I have two integer decisions variables, $x, x'$, that are either equal or greater than zero and either of them is to be equated to a third ...
707 views

### Can this be formulated as one inequality

I have two binary variables $x_1$ and $x_2$ and a non-negative continuous variable $y$. In addition, I have the following two parameters $u>q>0$. I would like to formulate the following ...
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### Linearizing max constraint Problem [duplicate]

I want to linearize a max constraint as below: In which x_(i,t),are binary decision variables and T is a constant. How can I linearize this constraint?
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### distance specific constraint

I have some points with determined coordinates $(a_i,b_i)$. A vehicle can move between these points based on rectangular distance. In more detail, we consider that the path between points is an ...
140 views

### Switching of decision variables to be larger than or equal to a decision variable according to an indicator variable value

I would like to seek some advice on modeling the following: I have two integer decisions variables, $x, x'$, that are either equal or greater than zero and either of them is greater than or equal to a ...
234 views

### 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 ...
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### How can I best handle symmetries in my MIP?

When dealing with mixed-integer-programs with many symmetric solutions it can take very long until the branch-and-bound-tree search is finished because symmetric optimal solutions cannot be pruned. ...
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### What is the definition for an integer-friendly constraint?

I have seen some papers claiming that their proposed model is integer-friendly. I would like to get more information about what type of constraints we can call integer-friendly. Probably, it can be ...
80 views

### shortest path problem,I want to write constraints in closed form

the constraints in the photo ,I need to translate to the closed-form I don't know how can I do this. Can you help? I need to write the mod file and dat file in Cplex for this problem
I have this problem described in natural language, and I was wondering whether it is relatable to any known problem. I have a directed acyclic graph. Each node can host a "probe". If node $i$ hosts ...