[gecode-users] Stability of a solution

[Christian Schulte]

Hi,

Not really knowing the details, I think this looks like a feasible plan even
though it all depends on whether the second point in your list is
sufficiently easy to do.

Cheers
Christian

--
Christian Schulte, Professor of Computer Science, KTH,
www.ict.kth.se/~cschulte/


-----Original Message-----
From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Philippe
Sent: Wednesday, October 16, 2013 11:04 AM
To: users at gecode.org
Subject: Re: [gecode-users] Stability of a solution

Hi Christian,
 
Thank you very much for your help.
Even if your solution is the one I had in mind, I'm not sure that we have
the same assumptions :
 
The constraints remains the same (for instance "allocate some task to
device", "A task cannot be allocated more than once",  ...) but the domain
of the variables change (for instance, the priority of a task, the duration
of a task) that's what I call "minor changes of the problem". but I can also
have new tasks, removed tasks. In that case, the changes are not so minor.
 
However, I was thinking about a solution similar to yours :
- find the best task's affectations of the new problem
- Once done, do the same but add the constraint that "the task's affectation
  to optimize must be the same than the one found in the old problem"
- check if the space fails. If not, retrieve the cost.
 
So, here is the pseudo code :
-----------------------------
 
// First, find the new task affectation
 
TaskAff * taskAff = new TaskAff(tasks, priorities, durations); BAB<TaskAff>
search_engine(taskAff, opt); delete taskAff;
 
while(TaskAff *taskAff = search_engine.next())
                {
                               taskAff->get_solution(affectations);
                               delete taskAff;
                }
 
// second, do the same but with a new constraint "affectations =
previous_aff"
//
TaskAff * taskAff = new TaskAff(tasks, priorities, durations, previous_aff);

If (! taskAff->failed())
       {
         taskAff->get_cost();
         delete taskAff;
        }
               
Are we ok ?        

                              
Cheers,
Philippe
                              


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