Employee training problem

Hi @zulfan.adiputra , the model is indeed infeasible, that is, no feasible solution exists. You can find out why by selecting the action Irreducible Infeasible Set (IIS) in the Math Program Inspector, if you use a newer AIMMS version (4.73 or newer) because older AIMMS versions have some limitations on determining the IIS.

After selecting this action, AIMMS will point to the constraints Attendants_definition(January) and Attendants_definition(February). For January the constraint becomes

Attendants(January) = 0

and for February

Attendants(February) - Attendants(January) = -2

(You can check this by selecting the action Create Constraint Listing in the Math Program Inspector.) Hence, Attendants(February) should be equal to -2 which is not possible because Attendants is nonnegative.

You can add two new parameters:

Parameter InitialAttendants {
	IndexDomain: t;
	Definition: data { December : 60 };
}

and

Parameter InitialTrainees {
	IndexDomain: t;
	Definition: data { November : 2 };
}

And then (probably) you want to add 

+ InitialAttendants(t) + InitialTrainees(t)

to the definition of Attendants.

Note that StartPeriod has the value ‘January’ in the case file that you are loading. This means that the planning interval of the horizon TimePeriod will start at January instead of November, and therefore, e.g., Attendants(November) does not exist. You might want to add

StartPeriod := 'November';

before the solve statement.