Dear all,

I have a problem with tranfering a constraint of my optimization problem into GAMS language. It is part of a kind of a Job-Shop Scheduling Problem. Maybe you can help me?

I want to manipulate the index t of the paramter e(ijt) and subtract (ts(ij)+1) from t. ts(ij) and x(ijkt) are variables, e_strich is a parameter.

In GAMS this looks like this, but it seems as if it doesn’t work like this. Any ideas?

E_Mittel(t) =e= sum( (i,j,k) , e(i,j,t-ts(i,j)+1 )* x(i,j,k,t) ) - e_strich;

Second problem with this constraint is, that e(i,j,t-ts(ij)+1)*x(i,j,k,t) should be only summed up if the value of t is between the variables ts(ij) [t_start] and te(ij) [t_end].

In GAMS it looks like this, but GAMS doesn’t like variables in the -operator. Again: Any ideas?
\
\
\
E_Mittel(t) =e= sum( (i,j,k) , (e(i,j,t-ts(i,j)+1 )* x(i,j,k,t)(ord(t)>=ts(i,j) and ord(t)<=te(i,j) ) ) - e_strich;

So I would like to know whether there is a simple solution for my problems or wheter I have to change my contraint completely.

Many thanks in advance and kind regards

Christian

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