Unanswered Questions
41 questions with no upvoted or accepted answers
6
votes
0
answers
649
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
156
views
4
votes
0
answers
384
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
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
2
votes
0
answers
155
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
105
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
2
votes
0
answers
134
views
Defining a highly non-linear function of integer variables
I have a complicated non-linear objective function of positive integer variables subject to linear constraints:
$\mathop {Min}\limits_{\underline x} f(\underline x)$
s.t.
$A\underline x\leq \underline ...
- 1,895
2
votes
0
answers
116
views
Achieve true determinism in CPLEX
I'm unable to achieve true determinism in CPLEX (I'm using the DOCplex python API).
Even if the best integer optimal solution is found without going to timeout (so it is expected to be unique), two ...
- 91
2
votes
0
answers
77
views
Making multiple branches in make_branch function of Cplex
In my current python code, I have used MyBranch call back of Cplex to make 2 branches and solve my model.
However, I now need to generate 4 branches after the first incumbent is generated. I need ...
- 1,895
2
votes
0
answers
271
views
Pyomo + Cplex - OSError: [Errno 22] Invalid argument
I am trying to get Cplex working with pyomo.
I have followed Cplex installation instructions has explained here: Downloading and setting up CPLEX for Pyomo
However when calling Cplex via pyomo I get ...
CommunityBot
- 1