At the moment I am performing a scheduling problem with time windows.
The model is very similar to the second model which can be downloaded from the AIMMS website (see link) execpt from a number of elements:
- I try to minimize the sum of all the changeovers that are used.
- Base unit is in minutes.
Initially, my model is able to solve using CPOptimizer 12.8 for all machines, where each job has to be scheduled after the "StartTime" and finish before an "Endtime".
After this solution I would like to decrease the StartTime by one week when a job meets a certain criteria and then solve it again.
When I run the procedure that decreases the Startime by one week and try to solve it again it finds a solution for only one of the machines and for the other two AIMMS hasnt been able to find a solution yet after more than 9 hours.
For the machine that could find a solution I repeated the procedure (decrease Startime by another week & Solve it). This did not find a solution after 27 hours.
Now my question is can I do something about this computation time, since the computation time increases and AIMMS is not yet able to find a solution when I decrease the StartTime by one week. Ultimately, I want to decrease the StartTime 3 weeks when jobs meet a the criteria.
If you need any extra information, please let me know!