Unanswered Questions
41 questions with no upvoted or accepted answers
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How to get an extreme ray in CPLEX
I am trying to get an extreme ray in a Benders decomposition when the primal subproblem is infeasible (so, the dual is unbounded). CPLEX below propose some function but no one works.
If you are using ...
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48
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Approximate Solutions and Solver Settings in CPLEX and Gurobi
CPLEX offers functionalities to approximate solutions for nonconvex optimization problems rather than guaranteeing global optimality. It includes an option to find solutions satisfying first-order ...
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Getting error in callback (lazy constraints) for docplex with Python to solve MILP
I am trying to use lazy constraints to solve my MILP problem. The details are given as follows.
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How to correctly use legacy callbacks in CPLEX with C++ to generate Benders' cuts?
I've been working on implementing Branch-and-Benders Cut using CPLEX version 20.1 with the C++ API, but I'm encountering some difficulties. I've followed the example provided by CPLEX, specifically ...
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Constraint formulation in MILP AGV Scheduling (using CPLEX)
I am currently working on a MILP formulation for optimizing AGV/AMR scheduling.
The model aims to optimize task scheduling across multiple missions using a limited set of resources. Parameters such as ...
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Solving a multi depot multi vehicle capacitated routing problem using global constraints
I have built the model, but at this point, I am not sure how do I ensure that each fighter starts from the assigned depot and comes back to that depot. here is my code. The ...
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CPLEX gets stuck in "Performing restart"
During solving my problem using generic lazy cuts (in Benders decomposition fashion), the solver gets stuck logging out "Performing restart 2" for several hours (while the time limit is 30 ...
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why this little constraint changes my whole program?
I'm trying to linearize a CP in ILOG CPLEX.
I have the following constraint that I want to linearize (I already simplified it with the big M) :
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Why are these two constraint equations not equivalent?
I've made a CP Model of an hospital in ILOG CPLEX and I want to test the performance of the CPLEX version of it.
In my CP model, I have the following constraint :
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3
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210
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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 ...
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Calling Cplex from R through a MPS-like file
I have a working - and long - R code to generate a mps file to be read by cplex.
Because I work with large instances I am finding troubles (too much time) in producing a large mps file.
Is there a way ...
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Weird behavior when using Automatic Benders Decomposition in CPLEX
I've encountered some weird behavior when using the Automatic Benders Decomposition in CPLEX.
I initially solved the MIP without BD and then I compared the results against the Full, Workers and User ...
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156
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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 ...
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Linearization of Conditional Constraints for MIP using Cplex
I'm currently working on a mixed-integer programming (MIP) problem and I'm trying to implement a set of conditional constraints in CPlex. These constraints involve decision variables that are indexed ...
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