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Hi Volker,

If an activity is deactivied, will all the constraints that contain this activity will be ignored?

For example, for constraints like a set of activities has a set of preffered time and a set of activities are not overlapping, they contain more than one activities. For instance, a not overlapping constraint R1 contains four activities,A,B,C,and D. If I deactivite A, will R1 be  ignored thoroughly or B, C and D still be not overlapping with each other?

Thank you Volker for your replay.

Sorry about that. It is just because the list is too long to get all the messages in one screenshot.
But the last one in the list is not 468, and generally, it is different from the single one given in the above.
My problem is I am not so clear about this tip. Does it mean that the last one in the list is not arranged a time and room and it is maybe problematic? When it is different from the one given in the above, which one should be more carefully treated? And from a very general point of view, when it fails to get a timetable, which type of activities should be paied more attention and be modefied, the placed ones or the unplaced ones?

When it failed to generate timetables, we always get this message, as the attached figure.
But which activity should I pay attention to? The first single one, ID: 468 in the figure, or the last one in the given list below?
I am a little bit confused about the difference between these two possiblely problematic activities.

Great thanks for any help!

Thank you Volker, I found the similar case in the manual.

We have 18 weeks a semester, the Machine Learning and Data Mining are two closely related subjects, each has 9 hours total duration and one hour most in a week.

Our school wants a timetable in which these two subjects have the same time and the same classroom, but they should be held alternately. That is, ML in odd weeks, i.e., weeks, 1, 3, 5, 7, ..., and DM in even weeks.

They are taught by different teachers.

How to set FET parameters to realize this?

Many thanks for any help.

I tried to attach the fet file but it is 1MB which exceed the allowed size.

So I attach a figure which shows the room constraints related to the playground.

There are totally 18 subactivities which prefer the room 10318, which is the playground, but they come from 9 activities.
So actually there are 9 different sport teachers, each teaches one class two times a week. The capacity of playground is 1000, every class has almost equal number of students which is 50.
So the maximum students simultaneously is around 450, and 8 extra rooms it needs to add by your calculation.
I can get timetables by adding 3 extra vitual rooms after tried several times. Actuall I can add as many as I want since even all these 9 calss have sports simultaneously is ok.

I have a question about your case, when you add 2 extra gym rooms, do you split the real gym's capacity to the added rooms or make them all have the same capacity as the real gym?

In your last replay, you said "How many students do you ant to place max in the playgroud?", do you mean the capacity of the real room?

Is the "Shared" room programly difficult?
You cannot view this attachment.

It seems the only solution until now.

I wonder is it possible to add one extra attribute for rooms, like "shared" or something else. If a room's shared=True, it will allow more activities in the same time as long as the capacity is satisfied, if shared=False, it is just a normal room.

One solution may be add more fake rooms, but how to restrict the student number not to exceed the capacity of the real room.

Different activities have not to be must the same time, but just allow them to take place at the only playground at the same time, actually it equals to allow the playground to held more than one activities in the same time as long as it doesn't exceed maximum capacity.

Hi everyone,

Does anyone have idea how to set the data to make it possible that allocating more activities in one big room in the same time.

We have a very large playground which can hold maximum 1000 students. We want different spots activities with the same or maytbe different teachers can take place on the playground at the same time. I have no idea how to set the fet data to make it work.

Thanks for any help.

Thank you so much for the replay from practical view.

Learned a lot.

Thanks for your detailed explanation.

I agree that optimize a soft constraint by local search may not find better results than alternatively tring different 100% constraints. That's a good tip for me.

So in practice in FET the weight either be 0% (not set the constraint) or 100% (set), what the weight between 0~100 will bring to us?

Of cause the correct way is to adding (reducing) constraints with 100% weight until a timetable cannot (can) be generated. Then, we at least have a workable timetable.
But finding proper constraint setting costs time. If you are lucky, you get the timetable with teachers max gaps with 100% and a value 3 in seconds. But maybe hours later, you realize it is impossible even with value 3 and a bigger value than 3 is nonsense for teachers. Then, a possible way is to set A teacher max gaps one by one for every teacher, but the problem are it is time-comsuming and which sub-group teachers should be selected.

In this case, maybe we can still set teachers max gaps with value 3 and a weight between 0 and 100, then minimize the fitness which is calculated as weighted sum of number of broken rules as in the source code. A perfet timetable is still impossible. But if we need to release timetables a day later, we just let the algorithm run and optimize obtained timetables for a day as far as possible. Maybe 80% teachers' max gaps with value 3 will be satisfied, as a bonus. We lose nothing by doing this.

The above suggestion may not practically useful. I just want to hear opinions.

The FET is a very good to use tool I have ever used, and the core idea of recursion is such a "beautiful" implementation.

Hello dear Liviu and Volker

I have read the history of FET that you used heiristic algorithms at the first, but the performance was not so satisfied. So the current very good-use FET came up.
I am wondering if we can obtain better timetables if the soft constraints (constraints with Weight_Percentage<100%) can be optimized further after a timetable is generated? Like use Simulated Annealing or other local search methods to fine-turning the timetable.
I always use MinDaysBetweenActivities to make the timetable more tidy, but sometimes I have to remove this constraint to find a available timetable. So I thought can I set the Weight_Percentage of MinDaysBetweenActivities to 90% or smaller value at first, then fine-turning the obtained timetable to reduce the soft constraints violation as far as possible?
Besides, is it a useful function for FET that one can manually adjust the obtained timetable?

I have a very large dataset, say more than 5000 activities. I have misplaced activity tags for around 3000 activities, so I want to delete these 3000 activities or just delete all activities and re-import all of them. How can I make it works instead of
1) creat a new .fet file from scratch
2) select the first activity, click remove, and long pressing the Enter button
both of them are time-consumiing.
Is it possible to add a "Delete/Remove/Clear all" button in the further version?
Many thanks for any suggestions.