# 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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4 votes
2 answers
307 views

• 2,265
3 votes
1 answer
162 views

### Optimization model testing tooling: likes, dislikes, and wishes

We’re [1] in the thick of building out a testing suite for decision models, starting with a focus on route optimization. There are several angles we care about [2] and are considering: unit testing, ...
5 votes
3 answers
390 views

### Is this arc routing formulation correct?

Let $G=(V,E)$ be a graph. I would like to identify an eulerian cycle in $G$ with minimum cost, with an integer programing approach: $x_{ij}$ are integer variables that denote the number of times that ...
• 51
4 votes
1 answer
364 views

### How can I transform this logical if-then constraint? [duplicate]

I want to know how to transform this logical if-then constraint? If $B=1$,then $A \ge C$, else $A=0$, where $A$ and $B$ are decision variables and $C$ are constants. $B$ is binary variable and $A\ge 0$...
1 vote
1 answer
189 views

### How to write this logical expression with Gurobi + Java, or express it as a big-m formulation

I am trying to write the following expression in Gurobi+Java or Gurobi+python, if it is more practical It could be expressed as a big-M formulation. \label{const4} \text{D}_{uv} = ...
• 11
2 votes
2 answers
206 views

### How to model not-met demand to next period?

I am trying to include to my model a demand shift. That is, I am having a fixed demand for each period (t), but because of capacity constraints I am not able to serve the whole demand for each period. ...
• 79
5 votes
1 answer
236 views

### Summation of Binary Variables Pushing a Binary Variable

I'm modeling a problem where I have a set of binary decision variables $x_{ij}$ that has a value of 1 if the person $i$ is allocated to day $j$ or 0 otherwise. I have another set of binary decision ...
• 53
2 votes
1 answer
114 views

### How to mathematically model this multi-objective optimization problem?

I have a system of $M$ machines and $U$ users. Each machine has a capacity in terms of number of resources. Let, machine $m$ has $\zeta_m$ resources. Each user has a service demand $d_u$ and there is ...
• 2,265
-2 votes
2 answers
69 views

• 385
2 votes
1 answer
183 views

• 235
2 votes
1 answer
184 views

### How to solve infeasible cplex model in GAMS?

I am facing this kind of error "Row 'eq1(14)' infeasible, all entries at implied bounds" in a problem that a GAMS script gets data from MATLAB. I have seen some posts about conflict ...
• 21
1 vote
2 answers
124 views

### Gurobipy trip scheduling empty stop problem

I am trying to create an optimizing model for a roadtrip: 10 cities in 14 weeks. For each city I have: a distance matrix to every city The rain for every week of the year My goal is to minimize the ...
• 11
2 votes
0 answers
61 views

### Resources on the soft aspects of modelling

Usually, the modeling involves those steps : Fuzzy Description ----(1)----> Clearer Description -----(2)-----> Mathematical model. Of course, it's not linear and a lot of iteration and re-...
• 309
3 votes
3 answers
131 views

### Minimum Disjointed Path Cover ILP formulation

I cannot find references for a Minimum Disjointed Path Cover ILP formulation. Given a directed graph G=(V,A), a disjointed path cover is a path cover with no common nodes between paths. We want to ...