Originally posted by: salais

Hello all,

I am working on implementing a model for the TSPTW (Travelling salesman problem with time windows) and am having trouble accomplishing the following:

I have a distance array indexed with tuples if int i and int j as follows (according to the tsp example)

int N = 4;
range Nodes = 1..N;

tuple edge {int i; int j;}
setof(edge) Edges = {<i,j> | i,j in Nodes};
int distEdges = ...;

After these the array "dist" contains the appropriate values. Additionally, i have a vector of integers+ as a decision variable as follows:

range Vd = 2..(N+1);
dvar int+ SNodes in Vd;

The problem is when i try and define the objective function
minimize sum (i in Nodes) dist[<i, Si]>;

However this yields a "cannot extract expression" error.
CP cannot extract expression: minimize sum(i in 1..4) dist[<i,S(i)]>. MyModel.mod

What am I missing?

Also, seems like my last post was deleted for some reason. If this was because of violation of rules of the forum etc. please let me know so I can correct this.
#CPOptimizer
#DecisionOptimization

Originally posted by: SystemAdmin

Hello.

Your post is not deleted, it is just on a different forum (OPL using CP Optimizer). You can find it on the following address:
http://www.ibm.com/developerworks/forums/thread.jspa?messageID=14896389

You can find there also my response.

Best regards, Petr
#CPOptimizer
#DecisionOptimization