Unanswered Questions
48 questions with no upvoted or accepted answers
6
votes
0
answers
227
views
OptionalIntervalVar enforced but not working OR-TOOLS
I'm using OptionalIntervalVar and then maximizing the starts. The optimal solution is not affecting the other variables that creates the ...
- 1,895
6
votes
0
answers
166
views
Modelling issue with precedence constraint in OR-Tools
I'm trying to solve an RCPSPDc model It is infeasible, although Ilog Cplex solves it, so I think I have a modelling issue. I have more constraints but the precedence is the one that makes it ...
- 2,865
6
votes
0
answers
651
views
Cplex is stuck after root node relaxation solution
I am solving an MIP through Benders decomposition (coded both generic and legacy callback versions), by employing Java with Cplex 12.9. For some of the instances, Cplex is stuck for two hours (time ...
- 5,442
5
votes
0
answers
124
views
Scale of largest CPLEX/Gurobi execution
I am trying to understand the CO2 emission of large scale optimization using CPLEX or Gurobi. Is there a published literature which addresses the compute usage of large scale executions?
- 1,895
4
votes
0
answers
159
views
4
votes
0
answers
385
views
CPLEX Python: Current subproblem model in branch and bound
I have an MILP problem and use CPLEX (Python interface). I am working on user heuristics for branching in the branch-and-bound procedure. With HSCallback I managed to get the information about the ...
- 251
4
votes
0
answers
107
views
Modelling issue with rcpsp and boolean expressions
I'm trying to solve an RCPSPDc problem in OR-Tools with CP-SAT solver.
In my RCPSPDc model (with discount rate) i want to set this objective:
$$\max_{s}\sum_{j\in J}\text{profit}_{j}\cdot \frac{1}{(1+...
- 2,865
3
votes
1
answer
210
views
Implementing Logic-based Benders decomposition on a single search tree
Currently, I am working on a scheduling problem and trying to approach it by the logic-based Benders decomposition method. Theoretically, I have everything, i.e., the master and sub problem(s), the ...
CommunityBot
- 1
3
votes
0
answers
101
views
cplex callbacks: getting the branching variable
I would like to obtain the number of the variable cplex branches on at the current node during B&B.
I try this by using the callback
...
- 75
3
votes
0
answers
648
views
Incorporating OR-Tools in a CMake Project
I'm trying to incorporate or-tools into my cmake project.
I've tried some of the suggestions given by the project maintainers, who give a few different ways to integrate or-tools in the readme and in ...
- 431
2
votes
0
answers
156
views
Why the column generation algorithm remains stuck at the same solution?
I was trying to solve a MILP by a column generation algorithm, and I noticed that the algorithm was stuck at the same solution, I tried to diversify the pool of initial columns, but the problem I ...
- 429
2
votes
0
answers
107
views
Automated Benders Using Annotations
I'm trying to solve an optimization model using Automated Benders with annotations using CPLEX library in C++. I've defined a master problem and N (number of supply nodes in my model's network) ...
- 1
2
votes
0
answers
67
views
Discrepancy between CPLEX interface solution and C API
I have a C API program uploaded here in Dropbox that is an LP. Here is the problem: When I compile the C file it gives me "1017 Not available for mixed-integer problems" while the problem is ...
- 5,874
2
votes
0
answers
94
views
MIP start in cplex using Java
When I am reading an "lp" file for the problem and using a MIP start reading from a "sol" file it works.
But when I pass on the same model directly to cplex (without writing lp) ...
- 5,874
2
votes
0
answers
64
views
Where is the relative gap from cplexbilp?
I am invoking cplexbilp (CPLEX 12.9) from Matlab R2022a. I request all 4 return arguments:
...
- 223