Questions tagged [docplex]
Questions related to the IBM Decision Optimization CPLEX (docplex) which is designed for modeling and solving optimization problems in Python.
21
questions
3
votes
2answers
52 views
CPLEX MILP Report all solutions found
I am running a MIP using DOCPLEX that generates several feasible integer solutions during the Branch and Bound search.
The node log updates every now and then based on the parameter setting.
However, ...
1
vote
0answers
82 views
How do I define multiple indices for the same set in python? (using CPLEX to solve a MILP)
I am using docplex in Python to solve a MILP and I am having some trouble defining the indices and sets of my model.
I want to translate $w,v,a\in W$ into Python.
In this case, $W$ is a set, and $w, v$...
2
votes
2answers
82 views
Docplex, CPLEX Warning 1036 :
I am trying to solve a large-scale MIP problem. I have the following errors, I know, it's about the data, but I can't change the data. Is there a method to deal with it?
...
-1
votes
1answer
74 views
For docplex, it's possible to set the number of iterations without improvement?
When running the cplex model, I noticed that the CPLEX repeats the same gap value several times. I ask if there is a parameter in docplex that limits the number of iterations without improvements or ...
0
votes
1answer
107 views
Assignment problem with variable tasks to be done
I'm dealing with a kind of assignment problem, in which I have a set of tasks $t$ to be executed by machines $w$, but these tasks depend on the variatns $v$ of components $m$ being selected, which is ...
2
votes
2answers
103 views
Constraint to handle the machine-configuration's change between initial position and its first occurrence in the process
I am working with a kind of a reconfigurable process planning, meaning that the same machine can have different configurations and perform multiple operations. Each machine has an initial ...
1
vote
0answers
21 views
Implement geometric constraint using DOCplex
currently I'm working on a wind farm layout optimization problem. I found an appropriate model in literature (Fischetti et al.) and now I'm trying to reproduce it using the Python API of cplex with ...
1
vote
2answers
208 views
Docplex Error: Model has non-convex objective
My objective function is $\frac{1}{2}w^{T}Vw - P^{T}w$ with $V$ a covariance matrix (hence semidefinite positive), $P$ a column vector and $w$ a vector of semi-continuous variables.
Given that the ...
2
votes
1answer
154 views
How to display the range of coefficients in docplex log?
A typical gurobi log can have a section where it shows the range of coefficients. Something like:
...
3
votes
2answers
156 views
Could DOcplex.CP recognize that it solves the graph coloring minimization problem?
I created a graph coloring DOcplex.CP model inspired by this example.
However, I do not know the number of colors in advance.
The goal is to minimize the number of colors (i.e., get as close as ...
3
votes
2answers
162 views
Rotated Second-Order Cone Constraints in docplex
I have programmed the model in here using Gurobi 9.0 in Python 3.7. To ensure playing within the boundaries of the licensing, I am trying to program it using CPLEX where we have broader flexibility ...
3
votes
1answer
166 views
Logical operation on an array in DOCplex
Here is a simple example of logical operation in docplex taken from here. Code below works fine.
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9
votes
1answer
369 views
Integrating genetic algorithm (or other heuristic methods) with CPLEX
[Topic to discuss GA and CPLEX]
I've seen some papers trying to integrate genetic algorithm with CPLEX, such as here and here. Although they integrated both, it is done in 2 different steps; that ...
7
votes
3answers
595 views
Constraint programming using solver: how to state the time limit of search?
Could someone give additional explanations about the TimeLimit of CPLEX for CPO?
I am using CPLEX to solve a problem of assignment and scheduling in which each task needs to be assigned to a worker, ...
5
votes
1answer
164 views
Precedence constraints using binary variables - DOCPLEX
I would like to establish a precedence constraint to ensure the precedence relation of tasks. I have a set of tasks available, but required tasks are not always the same. It means, the tasks executed ...
5
votes
1answer
175 views
Scheduling with transition costs - DOCPLEX
I am dealing with a kind of scheduling problem. I have a set of tasks to be executed by a set of machines. It is known that different machines are able to execute the same task, but each machine can ...
8
votes
1answer
355 views
When using docplex.cp is it possible to get all feasible solutions?
I would like to solve an ILP and get all feasible solutions (even the worst one).
How could I do that using docplex.cp?
I've seen a similar question in: Using CPLEX "solution pool" to count ...
5
votes
0answers
56 views
How to handle constraints in docplex to states the relation between two variables?
I am using docplex.cp and I need to state the following constraint:
$$\sum_{c}(X_p{_w}_{cj}+X_{p+1}{_{w'}}_{cj+1})\leqslant T_w{_{w'}}_{,jj+1} + 1$$
Knowing that the binary variables are:
$X_p{_w}...
7
votes
1answer
97 views
DOCPLEX: tips to manipulate data input (binary parameter)
I am coding a MIP problem in docplex and I would like to ask for some tips.
I would like to input a binary parameter that states a compatibility relation:
I have a set of characteristics $H$ to be ...
5
votes
2answers
457 views
How to establish constraint between variables with multiple indexes using CPLEX in Python
I am new in CPLEX and I am using docplex in Python to solve an ILP.
I would like to translate the following constraint in docplex:
$$\sum_{c}(X_p{_w}_{cj}+X_{p+1}{_{w'}}_{cj+1})\leqslant T_w{_{w'}}_{,...
10
votes
1answer
171 views
DOCplex adding columns
When using DOCplex to implement column generation, is it possible to add columns as an object, as opposed to creating a variable and then modifying the coefficients in the constraints?
Edit: In ...
