Hello everybody,

I’m new to GAMS and this group and I hope to find some help here

For my model, which I have to use in my bachelor thesis, I have to use a minlp solver. So the only one, which is included in the basic GAMS version is Bonmin.

When I run my model with the B-Hyb algorithm, it solves very fast, but I get a solver message: OA on non-convex constraint is very experimental.

When I change the used algorithm to B-BB it takes veeeerry long… So do you have any suggestions for the option file?

Using the B-Hyb algorithm there is another mystery and I don’t really don’t know whats wrong with it…

In my model I use two sets:

Sets

t time_steps / t1*t24 /,
u units / u1*u18 /

;

When I change t to 35 the model solves very fast, so does it at t = 37. But when I use t=36 it takes “hours” and returns no feasible solution. So does it with 47 (fast), 48 (slow), 49 (fast), 71 (fast), 72 (slow) and 73 (fast). So it can be said, when there is factor 12, it has problems solving the model. Any ideas?

## Thank you all!

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