Originally posted by: BabakArh

I start to code a simple schduling problem

5 job with p_time=4

1 machine

my obj is sum of completion time

After I solve my model, I get 0 as start time for all jobs.

here is my code

/*
 * Created by SharpDevelop.
 * User: bbka2
 * Date: 05/18/2016
 * Time: 8:54 PM
 * 
 * To change this template use Tools | Options | Coding | Edit Standard Headers.
 */
using System;
using System.IO;
using ILOG.CP;
using ILOG.Concert;


namespace test_here
{
    /// <summary>
    /// Description of CMAX.
    /// </summary>
    public class CMAX
    {
        public IIntExpr makespan;
        public IIntervalVar[] act_;
        public IIntExpr[] end;
        public CP scheduler;
        public IObjective obj;
        public int n_;
        public CMAX()
        {
            initial();
            disp();
        }
        public void initial()
        {
            n_=5;
            scheduler=new CP();
            act_=new IIntervalVar[n_];
            makespan=scheduler.Constant(0,"MakeSpan");
            for (int i = 0; i < n_; i++) {
                act_[i]=scheduler.IntervalVar(4,"act"+i.ToString());
                act_[i].EndMax=30;
                act_[i].EndMin=0;
                act_[i].StartMax=30;
                act_[i].StartMin=0;
                act_[i].LengthMax=4;
                act_[i].LengthMin=4;
                Console.WriteLine(act_[i].ToString());
                makespan=scheduler.Sum(makespan,scheduler.EndOf(act_[i]));
                Console.WriteLine(makespan.ToString());
            }
            scheduler.NoOverlap(act_);
            scheduler.AddMinimize(makespan);
            scheduler.SetParameter(CP.IntParam.SearchType,CP.ParameterValues.DepthFirst);
        }
        public void disp()
        {
            if (scheduler.Solve()) {
                //scheduler.Solve();
                Console.WriteLine("this is th obj {0}",scheduler.ObjValue);
                for (int i = 0; i < n_; i++) {
                    Console.WriteLine("the act {0}, has start {1}",i,scheduler.GetStart(act_[i]));
                }
            }
        }
    }
}

This follows

https://www.ibm.com/developerworks/community/forums/html/topic?id=56a12027-d2cb-4251-90ae-ca8cb0ea5af5&ps=25

Originally posted by: BabakArh

I wrote sum(p_time) for abject, it could give me 4+8+12+16+20

and for the start time i get 0 for all. and it is wrong.

is it wrong what I code which gave me 0 for start time?

Originally posted by: BabakArh

I thinl My refrences doesnt work at all

I add this constraint to force cp, to change the start times but it doesnt work either

for (int i = 0; i < n_; i++) {
                for (int j = 0; j < i; j++) {
                    scheduler.Or(scheduler.Le(scheduler.EndOf(act_[i]),scheduler.StartOf(act_[j]))
                                 ,scheduler.Le(scheduler.EndOf(act_[j]),scheduler.StartOf(act_[i])));
                }
            }

Originally posted by: GGR

Hi

You have only created the constraint. You have to explicitly add the constraint to the solver. Please have a look on:

http://www.ibm.com/support/knowledgecenter/SSSA5P_12.6.3/ilog.odms.cpo.help/CP_Optimizer/User_manual/topics/model_formulating.html?lang=fr

The reason why is that you can manipulate the constraint in other way than pure condition to verify to a solution, for example writing complex Boolean expressions.

Hope that helps

Originally posted by: BabakArh

about the constraint u r right. i add the constraint to model it worked.

Thank u.

that means even all global constraint has to be written like this

iConstraint ct=model.noOverlap(iInterval[]);

model.add(ct);