[Help-glpk] Glpsol IF-THEN-ELSE expression problem

[Bill]

Hi everyone,

I'm new to Glpk. I'm trying to model an optimazation problem for university 
timetabling. In the objective function, I need to minimize the following 
function,

g(sum sum T[i,j,k])

g() returns 1 if (sum sum T[i,j,k]) > 0 else 0

The problem is T[i,j,k] is a variable, IF-THEN-ELSE cannot handle variables in 
the logical expression. Is there a way around it?

Can anyone help?

Thank you very much
B. Song