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

[Meketon, Marc]

A lousy way of doing it is to define a binary variable  y  (so y = 0 or 1) and

 

minimize   y

 

s.t. sum sum T[i,j,k] < M*y

 

where M is some suitable large value.  If the sum sum T[i,j,k] <= 0, then y is 0.  Otherwise, y is 1.

 

I'm sure that other users will have better ways of modeling this.

 

-Marc

---

From: address@hidden on behalf of Bill
Sent: Wed 2/14/2007 5:47 PM
To: address@hidden
Subject: [Help-glpk] Glpsol IF-THEN-ELSE _expression_ problem

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



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