I have a production production problem with an objective function that consists in different summations (regarding setup, inventory, standby and energy costs) but right now for a certain purpose I am neglecting the last one. Based on the negligence of energy costs in the objective function, various optimal solutions for the production problem exist, as various changes in the sequence have no efects on the objective function at this point. Based on their individual sequence of machine states, the resulting solutions difer in energy costs and consequently in total costs (of course the variables and constraints related to energy are included in the model)

What I would like to do now is to storage a low number of different optimal solutions.

I have read the solution pool documentation and even try to include the code from the GAMS model library "soolmpool" but I receive the following error "symbol is not a set" and it seems like the problem is the "u" because there is where the pointer goes once I click the error message.

The problematic line:

Code: Select all

```
Alias (soln,s1,s2), (*,u);
```

I hope I explained my self properly and that someone could give me some insights about how to solve my problem.

Best regards,