Dear All,
When I generate the timetable, my usual approach is to insert step by step the constraints and running the solver to get a timetable. Of course, at the beginning everything runs smoothly, but after inserting a number of constraints the solver becomes slower because the number of constraints starts getting significant.
My question is: is it possible to run a solver feeding a previously generated timetable as starting point? Being an optimisation problem, I would expect that giving a reasonable starting point the solution would be got more easily than a full start from scratch.
Best regards,
Corrado
Dear Corrado,
It is not possible. You cannot take a solution and make it better in terms of hard (100% weight) and/or soft (<100% weight) constraints. You need to start from zero each timetable. It is not possible even to start with a partial solution (a part of activities allocated in time and space).
My advice is to generate on a file with all the activities and only the not available constraints. If it succeeds in a reasonable time, you could add also min days between activities constraints and generate again. Then, add all the remaining constraints and try to generate, possibly on more threads to see which solution is found first. Then, if not successful, deactivate or lower the noncritical constraints.
Dear Liviu,
Many thanks. Maybe it is something that could be introduced in the future?
Also, another useful thing could be a drag and drop feature in the timetable view (for instance vertical view by rooms).
Thank you for actively developing this amazing tool!
Corrado
Hello, Corrado,
I will add your suggestions in the TODO list. But what I meant by "You cannot take a solution and make it better in terms of hard (100% weight) and/or soft (<100% weight) constraints." is that it cannot be implemented in FET, because it is unfeasible/impossible. The solution must be constructed from zero placed activities, increasingly adding activities.
About drag and drop:
1) It is not in my exact area of expertise;
2) Even so, I am ready to give it a try, since many users suggested it. But I need financial support. I posted two topics about this: https://lalescu.ro/liviu/fet/forum/index.php?topic=6367.0 and https://lalescu.ro/liviu/fet/forum/index.php?topic=6366.0 ;
3) Recently, we had some contributions from other users - other tools using fet files. Please see: https://lalescu.ro/liviu/fet/toolslinks.html . There might be some tools, like the recently added reFET link, which might allow drag and drop.
Could you please tell me your complete name or alias you would like me to add as the person who suggested these things in FET? "corra", "Corrado", or a more complete name?
corra is fine, thank you!
Thank you! I wrote down your suggestions in the TODO file.