odd and even weeks - block the same Rooms

[Volker Dirr]

No. you might do it also with an other trick. Please read "Add a fortnightly activity":
http://www.timetabling.de/manual/FET-manual.en.html#id_36

[Liviu Lalescu]

Thanks for your reply, is that the only way to achieve this by making 10 (2*5) days? and need to double all the activities? (also need to double other time constraint?)

You have basically two ways, as Volker said. The exact way (in this topic) and using tricks like in Volker's manual. Please let me know if these are clear or we need to talk some more.

Also, quotes from the FAQ:

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Q: Can I work with fortnightly activities like in older FET versions?

A: You have to use some tricks. It would be difficult to consider fortnightly activities into the new FET algorithm (from 5.0.0 up). But I think you can apply this: for instance, I suppose that you would like the first week to have activity A1 (teacher T1, student S1) and A2 (T2, S2), and second week A3 (T1, S2) and A4 (T2, S1) (simultaneously). You could define a weekly activity A (T1, T2, S1, S2). If you need 2 rooms for A, then you can define dummy A' (no teachers, no students) and constraint activities same starting time A and A' and add rooms for A and A' .

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-- This entry by Regis Bouguin --

Q: A trick to deal with fortnightly activities (my institution has a lot of fortnightly activities):

A: I divided hours in two, the first half (8.00 to 8.30, 9.00 to 9.30, ...) represents week A, the second half (8.30 to 9.00, 9.30 to 10.00, ...) represents week B, fortnightly activities have duration 1, weekly activities have duration 2.

I created an activity tag 'Start hour'. It should be added to each weekly activity to make sure they start at the same time (same day + same hour) on each week. Otherwise, an activity with duration 2 can start on a second half of hour in the timetable, so this activity is placed on a certain day and at a certain hour on week A, and on the same day but at the next hour on week B.

Add time constraint: activities with all teachers, all students, all subjects, activity tag = 'Start hour' have a set of preferred starting times: Monday 8.00, Monday 9.00, ...

It works fine and I got good timetables with strong teachers time constraints.

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Besides, I want to know the usage of the following:

"A set of activities occupies max time slots from selection" and

There is a button Help in the dialog of this constraint. Please read it and come back here or in another topic if more help is needed.

We (the FET authors and other users) found many usages of this constraint. You can for instance make two teachers or two students have the same timetable (if they have m > n activities, add occupy max occupied slots m, all their activities, select all slots of the week - in case they want to come and leave school together). Or, the documented feature, you can make a teacher or a student have activities in some exact slots. Another usage was in: http://lalescu.ro/liviu/fet/forum/index.php?topic=1782.0 (long topic, no need to read though if you don't have time).

"maximum simultaneous activities from a set in selected time slots"

Thanks a lot again!

Again, please read the Help button of the dialog in this constraint and come back here or in another topic if more help is needed.