May I know how to solve the duplicate column error since I have put the Xconstraint(i,l,g,g0) so that duplicate column does not occur? Whoever is the sender Q(i,l,g,g0) of the product cannot be the same one who is receiving the product Q(i,l,g0,g) to satisfy the local demand. May I know if there is any other way to solve this problem instead of using the constraint such as X(i,l,g,g0) + X(i,l,g0,g) <= 1 since the system does not apply this constraint at all?
Best answer by Chris Kuip
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