Dear Staff,

I am experiencing a weird behaviour within one of my models implemented in AIMMS.

I have a simple flow model.

Among others, there are the following variables:

F, continous variable

X, continuous variable

The variables do not have lower or upper bounds, so they are free.

Then there are some flow balance constraints in the network (i.e. flow in equal to flow out).



The model works very fine when only variable F is used.

But when I add the following constraint:

F = X

then I get an infeasible solution.

While if I add the constraint

F