Originally posted by: Rahul Ghate

 I am working on RCPSP and want to apply Preemption to it. I have divided the duration of every task into equal parts. Now after doing that I am unable to apply Precedence constraints to each of individual unit duration of task. Which function can I use for that.

using CP;

int NbTasks = ...;
int NbRsrcs = ...;
range RsrcIds = 1..NbRsrcs;  

int Capacity[r in RsrcIds] = ...;    
tuple Task {                 

  key int id;
  int     pt;
  int     dmds[RsrcIds];
  {int}   succs;            
  {int} pred;
 }
{Task} Tasks=...;


tuple sub_task{ 
 Task task; 
 int p_no;

 }
  {sub_task} sub_activities = {<t,i > | t in Tasks, i in 1..t.pt  };  
 dvar interval itvs[t in Tasks]  size t.pt;
 dvar interval a[p in sub_activities] size 1;
 cumulFunction rsrcUsage[r in RsrcIds] = 
  sum (p in sub_activities: p.task.dmds[r]>0) pulse(a[p], p.task.dmds[r]);
 minimize max(t in Tasks) endOf(itvs[t]);

subject to {
   forall (r in RsrcIds)
    rsrcUsage[r] <= Capacity[r];
   forall (t1 in Tasks, t2id in t1.succs)
    endBeforeStart(itvs[t1], itvs[<t2id>]);

}     

 execute {

  for (var p in sub_activities){
 writeln("subactivity of " + p.task.id + " - " + p.p_no + " starts at " + a[p].start + " Ends at " + a[p].end);  
  } 
 }


Please Help.

Thanks in Advance

It looks like you are using constraint programming to solve your model (using CP).

Can you please post your question on one of the CP optimizer forums here: https://www.ibm.com/developerworks/community/forums/html/category?id=33333333-0000-0000-0000-000000000268

Originally posted by: Rahul Ghate

Ok Sir. Thanks for your directions.