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, by respecting a correct sequence. There is a cost of changing the worker and the cost of tasks execution changes from one worker to another.
When I do not state the time limit, it takes about 15 hours to return a result. When I stated the time limit = 10 seconds, it took about 10 seconds to find a correct result, correspondent to that found by the solver after turning during 15 hours.
The only difference between both results is the sequence of tasks executed by the same worker, but it does not imply on the objective function.
My questions are:
- Why the solver takes 15 hours to obtain a result if it could take just few seconds to obtain an equivalent result?
- Could it be related to the fact that there are many possibilities of sequencing the tasks without changing the objective function value?
- How to know which is the most appropriate time limit to use?