Hi @Eddy. Using a binary variable inside one of the (multi) objectives should not be a problem. I have no idea why you get this error; I would need the AIMMS project to find out. Could you please add your project here, preferably after adding it to a zip file, or send it to our support by email if your project contains sensitive information?

Hi Marcel,

thanks a lot for your reply!

The AIMMS Project is atteched. (there is only one AIMMS Project and only one set of data in the folder)

I am also not so sure if the “SolveMultiObj” Procedere is correct, bc when I let this run the first time it gives me this solution:

but if i let it run again it gives this solution:

Do you know what the problem could be here?

But back to my first question:

Is it possible to change the v_supply variable to a binary one? 

So it says:

Y is 1 if source i is used for product i and is 0 if it’s not opend? So that the created jobs do not depend on the amount of the product..

I hope you can understand what i am trying to say.

Many thanks in advance!

Best regards,

Eddy

Hi @Eddy. Thanks for sharing the project. The procedure SolveMultiObj misses a call to GMP::Instance::Generate. I added that function and used ‘mp_Cost’ as its argument because I could not find ‘mp_BW’.

If I run SolveMultiObj then I do not get an error and if I run it multiple times then I always get the same solution, namely your second solution (with v_objectiveFunctionCost equal to 118).

I have not been able to reproduce the error with the binary variable.

Not sure whether I understand your question about Y but you could create a constraint v_supply(...) <= M * Y(...), where M is some large positive value, and then use Y, instead of v_supply, in the definition of v_totalCreatedJobs.

Thanks for your help @Marcel Hunting !

the SolveMultiObj is running now.

I tried to implement the constraint v_supply(...) <= M * Y(...) like this:

But now the solution for the objective function v_objectiveFunctionSocial and the solution for v_totalCreatedJobs always stays the same..

The new file is attached..

Do you know what the problem is?

Thanks!

Hi @Eddy. For your model its is beneficial to set all v_Y to 1 because the model is (indirectly) maximizing the sum of all v_Y(i_source, i_destination, i_product, i_transportationmode). This is because you use a weight of -1 for v_objectiveFunctionSocial in the procedure GMP::Column::SetAsMultiObjective().

If this is indeed the way you want to model v_Y then you should realize that it is beneficial for the optimizer to set v_supply(i_source, i_destination, i_product, i_transportationmode) to a small positive value in order to make v_Y(i_source, i_destination, i_product, i_transportationmode) equal to 1.

In my opinion it makes more sense to (indirectly) minimize the sum of all v_Y, and therefore use a weight of 1 for v_objectiveFunctionSocial in the procedure GMP::Column::SetAsMultiObjective().