Originally posted by: Adriano199

Hi everyone, 

I'm trying to schedule some tasks that part of an item do be done that follows a recipe however some tasks can be done in different machines. E.g

Product A-:

Task       Machine    alternative machine

P1        Drill1                Drill2

The problem is I'm not able to do this without either with the order of the tasks and the precedence's :-/.

How to solve this? 

Any Idea? By the way I'm using the an example as a template 

Here is my code:

The Model

using CP;

{string} Task  = ...;

{string} Resource  = ...;

tuple Distance {
  string pre;
  string post;
  int    dist;
};

tuple Precedence {
  string pre;
  string post;
};

int taskDuration[Task] = ...;


{Distance} max_nf = ...;

{string} tasksOnResource[Resource] = ...;
{Precedence} precedences = ...;



dvar interval a[t in Task] 
  size taskDuration[t] ;

  

dvar sequence resourceUsage[r in Resource] in all(t in tasksOnResource[r]) a[t]; 

execute {
                cp.param.FailLimit = 10000;
}

minimize max(t in Task) endOf(a[t]);

subject to {  

  
  forall(r in Resource)
    noOverlap(resourceUsage[r]);

  forall(t in precedences )
    endBeforeStart(a[t.pre], a[t.post])
    ;
    
    
  
  forall( t in max_nf )
    endBeforeStart(a[t.pre], a[t.post], -t.dist);

  
};

 and the data file

 ComputerTypes = { 
   A, 
   B 
   
};

ActivityTypes = { 
   P1, 
   P2,  
   P3, 
   P4, 
   P5, 
   P6, 
   P7,
   P8,
   P9,
   Z11,
   Z22,
    Z222,
   Z33,
   Z99
};

ResourceTypes = { 
   Drill1, Drill2,punch1,punch2,insp,rfid,stor
};

requiredQuantities = [10,5];
max_nf  = {
     <P1,P2,30>,
     <P1,P3,30>,
     <P3,P4,0>,
     <P5,P6,0>
};
activities = #[
//     task,ptime,ressource,precedence
   A:
        { <P7, 750, stor, {}>, 
          <P1, 820, punch1, {P7}>,
          <Z11, 820, Drill1, {P1}>,
          <Z33, 740, Drill1, {Z11}>,
          <P4, 830, Drill1, {Z33}>,
          <P9, 826, insp, {P4}>},
          <Z99, 826, Robot, {P6}>},
  B:
        { <P7, 750, stor, {}>, 
          <P5, 840, Drill2, {P7}>,
          <P6, 740, Drill2, {P5}>,
          <P2, 830, punch2, {P3}>,
          <Z22, 840, punch2, {P2}>,
          <P9, 826, insp, {Z22}>},
          <Z99, 826, Robot, {Z222}>}
]#;

Thanks for the help

Originally posted by: ol

Hello,

you can use an Alternative constraint: your task P1 will be associated to two tasks P1OnDrill1, P1OnDrill2 and the alternative constraint ensures that only one of these two additional tasks is present, and is linked to P1.  You can see for instance the example sched_optional.cpp.

Regards

ol