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Hello,

Activity preferred times adds X (not available) with any weight. The largest value for each slot wins. So, you will come out with: 99% denied in all slots without Mon aft, Tue mor, and Wed; 95% denied on Wed, and 90% denied on Mon aft. Yes, it is a good strategy.

Maybe another method, please think and try a bit: activities occupy min time slots from selection, for all activities of that teacher. Unfortunately, only 100% allowed, but it instructs FET which slots should be occupied with activities of this teacher.

Or maybe combine the above approaches.

I tend to prefer only 100% constraints, because those 99%, 95%, and 90% must be broken to produce a timetable, and might waste time. My only "allowed" <100% is for min days. I admit I don't like especially preferred times with <100%.

Hola,

You are welcome!

If you have A1 (Id 12, John, English, 6A), A2 (Id 13, John, English, 6A), and A3 (Id 25, Brown, Spanish, 6A), you can add a constraint min 1 days 100% between (A1, A2, A3). You can add any (sub)activities in such a constraint.

You could also use other constraints, such as:

- Constraint students activity tag max 1 hours daily 100%.
- Constraint students max 1 activity tags per day from a set (Tag English, Tag Spanish).

I would prefer min days, it is the most efficient, but you might need more work to add the constraints for each desired group of activities.

Hola!

Constraint min 1 days between activities, 100%.

Prego, Giusi! 

Buongiorno,

Scusi l'inglese:

Please think of constraints: activities same starting time, or activities occupy max time slots from selection. This last one can be used in a progressive approach, until FET cannot find solutions anymore; I mean: A1(T1,St1), A2(T2,St2), A3(T3,St3), A4(T1,St2), A5(T2,St3), A6(T3,St1): select all slots of the week, max occupied = 5, then 4, then 3, then 2, if FET still finds a solution.

Teachers min 2 hours daily allows free Saturdays. You could then use other constraints to minimize teachers' presence on Saturdays.

I used VScode for the xml files, no pb, I'm just surprise about the "anywhere" but ok.

The constraints can be ordered in any way. You can order even in the FET GUI, with Up/Down.

Does this mean that doing this (which is what I've been doing so far) distorts the intended meaning of the constraints, or does it "only" increase the computation time for the FET generator?

A1, A2, A3 min 1 days between them, two constraints with 95% and respectively 97%, it is equivalent with 1 - (5% x 3%) = 99.85%, which is very hard to break.

If I understand correctly, it's therefore not a problem to have "multiple versions" of such constraints active simultaneously—is that right?
And does that mean my idea of using decreasing weights for increasingly smaller time ranges is correct after all?

You can have multiple preferred times without problems like min days between activities, but I am not sure about your way about your approach with decreasing weights for smaller time ranges.

Why not teacher min 2 hours daily?

If you know that the teacher T must have activities on Saturday, you could use activities occupy min time slots from selection. If teacher T can have activities on Saturday or be free on Saturday, I don't see for now a solution.

Hello, Anthony!

The board for this post is correct.

1) Please open the fet file with an XML editor or text editor. Search for <Time_Constraints_List> and </Time_Constraints_List>. Between these two are the time constraints, such as: <ConstraintTeacherNotAvailableTimes> ... </ConstraintTeacherNotAvailableTimes>. Please see an example of how this constraint is written in XML. Just add new constraints in this section, anywhere, but not inside an existing constraint.

2) Min days between activities constraints accumulate weight (the weight is stronger on two or more constraints for the same activities). You need to enable level 1, XOR level 2, XOR level 3, not two or more simultaneously. The reason for accumulation is that FET checks each constraint in turn.

You can activate/deactivate all constraints of a level with an advanced filter for comments, select all of them, and click activate/deactivate.

Activities preferred times constraints: for each activity, each cell of a table n_days x n_hours takes the maximum of each constraint as the final weight of not allowed, and FET only checks once the constraint for each activity.

You're welcome! 

Good afternoon, Maria, and welcome to the forum!

You need to use constraints of type teacher(s)/students (set) activity tag max hours daily/continuously (after you tag the activities as needed).

Feel free to share your fet data file, and I'll add the constraints as needed.

On Thursday, 9 July 2026, FET-7.9.1 was released. From the ChangeLog:

  - Bug fixes when saving/restoring the settings to/from an ini file (discovered with the help of Andrea Primiani). The bugs appeared when saving the settings to an ini file, in which case the settings were not the current ones, but the ones from the previous FET session, and when restoring the settings from an ini file, in which case the user could have met useless warnings for some options, like checking for updates on startup or enabling the option 'group activities in the initial order'; also, in these situations, when restoring the settings from an ini file and meeting these warnings, the settings might have been retrieved/set incorrectly if the user clicked 'No' or 'Cancel' in the respective message boxes.
  - Corrected a compilation warning, for a variable set but not used (reported by Andrea Primiani).
  - Minor interface improvements.
  - Updated the Russian translation, by Alexey Chernous.

We solved the problem with the help of Google Remote Desktop ( https://remotedesktop.google.com/home ). Thanking Google for this freely usable tool!

It was not a FET bug.

I answered. Note that I prefer email instead of forum PMs (easier to manage).

Your trick with Stebe Gasper seems interesting and useful. Another maybe better practical trick, because FET is not so constrained: add all his activities without a teacher, and constrain them to be max 2 simultaneous in all slots. Use activity tags to explain the teacher. You don't need to choose which activity is in first or second week.

About import: select field separator ";", and no text quote. Then select correctly the fields in the next dialog.

I have free time. If you need, we could make a remote desktop with Google and I'll check your problems on your computer.

Hello, Mojca,

I imported your students, then the activities import complained about 2 missing students sets. So I added them in the CSV file, imported again the students, then successfully imported the activities. I attach the normal warnings I got and the final fet file.

I work with GNU/Linux, but should be the same on any platform.

Please let me know!

PS: I just saw that teacher Stebe Gasper appears twice (second time with two spaces in the middle).