unexpected VARSYM in zimpl

Question

I am getting an unexpected VARSYM in my Zimpl code. Here is a portion of my code:

param T := 0.8;
var S[Sensors] binary;

minimize nb_sensors : sum < i > in Sensors : S[ i ];

subto fd:

     1- prod <k,l>  in Sensors*Pipe : (1-ord(Proba[k,l],1,1) * S[k])  >= T;

It seems that the error is because I have a variable (S[]) which is inside the function (prod), do you have any idea about this issue?

Answer 1

What is T, a variable or a constant? Have you tried to write the product in brackets:

1- (prod <k,l>  in Sensors*Pipe : (1-ord(Proba[k,l],1,1) * S[k]))  >= T;

or to rewrite is as:

prod <k,l>  in Sensors*Pipe : (1-ord(Proba[k,l],1,1) * S[k]) + T <= 1;