I am trying to build a constraint of the form
x[i j] +x[j i] <y[i][j] where
x is a decision variable if arc
ij is used.
The arcs are defined in terms of tuples. However, not all arcs are available in that
[2 3] is presented while
[3 2] is not.
y[i][j] is a decision variable too but it is using nodes (not tuple values) representing if the two nodes are covered by the same trip or not.
How can I write this constraint?
Note: When I run it using this constraint, it uses only same arc tuples
forall(i,j in Setlocations : i < j && i!=j ) forall( g in Graph : g.o==j && g.d==i ) forall(m in Graph : m.o==j && m.d==i) x[g] + x[m] <= z[i][j] ;