tuple Order{   
 	 key int no;
	 string origin;
	 string dest;
	 int volume;     
	  }
	  
{Order} orders =...;

tuple Path {
	key int id;
	int price;
	{int} sequence;
}

{Path} paths = ...;
{Path} orders_paths[k in orders] = ...;

1. I want to define a int+ variable q[k in orders][p in orders_paths[k]].  Do you know how to define q? The size of orders_paths[k] is different.

Making Decision Optimization Simple

{int} S={1,2,3};
 tuple path
 {
   int i;
   {int} Sequence;
 }
 
 {path} paths={<1,{1}>,<3,{3}>};
 
 int a[s in S][p in paths]=(s in p.Sequence);
 
 execute
 {
   writeln(a);
 }​

[[1 0]
         [0 0]
         [0 1]]​

I am working on a bi-level programming problem with the KKT condition actually. I guess the reason for error is because there are different number of paths available for different  orders. 

For instance, there are two orders and three paths. Order A could select one path from three alternatives (p1, p2 and p3), while Order B could select p2 or p3 only. 
So decision variables are  q[1][1], q[1][2], q[1][3], q[2][2] and q[2][3]. Then CPLEX can't get a feasible dual formulation.

Do you have any idea to express q[k][p] more tight?

{int} S={1,2,3}; tuple path {   int i;   {int} Sequence; }  {path} paths={<1,{1}>,<3,{3}>};  int a[s in S][p in paths]=(s in p.Sequence);  execute {   writeln(a); }​

[[1 0]         [0 0]         [0 1]]​