Dear Sir

Please, I am working on a goal programming model for optimal index tracking portfolio selection problem with GAMS.

the model stops and says ( Integer infeasible)

any help in this context

attached the gms file and data files

Many thanks in advance

stocksreturn.txt (6.67 KB)

Indexreturn.txt (262 Bytes)

Trial Best 10-10-2023 - Copy (2).gms (1.33 KB)

It seems that your model is unbounded. You might want to set proper lower bounds on variables d1,d2,d3,d4.

I hope this helps.

Fred

Many thanks for your interest and reply

Actually these are positve and negative deviations that need to be minimized, hence an upper bound is needed. However i tried to add an upper bound with 0.03 but the problem is still exists.

Thanks for your time and support

Hi,

Then I do not understand the model.

Look for example at free variable d1. It occurs with coefficient 1 in the objective which is minimized. Other than that it occurs only in constraint “Tracking”, also with coefficient 1. This is a “=L=” constraint. So the solver will make d1 “as negative as possible”. In the current model that means -inf wich means the model is unbounded.

I hope this helps!

Fred