Possible new mode: Two weeks (odd and even weeks)

[Liviu Lalescu]

Dear FET users,

In my country, Romania, and possibly in other countries, some colleges consider a two-weeks timetable. Some activities are fortnightly and they take place in an odd or in an even week.

Maybe we could introduce a new mode, Two weeks. This mode will add a count to each activity: Weekly, Odd week, Even week. This will be the only visible (external) data change.

Internally, FET will double the teachers and the students. Say there are students years: "Y1", ..., "Y5". Then FET will internally double to "Y1_odd", ..., "Y5_odd", "Y1_even", ..., "Y5_even". The odd years will contain the Weekly and Odd activities of the respective year, and the even years will contain the Weekly and the Even activities of the respective year. Similarly for the teachers.

In this way, FET will correctly optimize the max gaps constraints.

What is your opinion?

[Volker Dirr]

I know that here (Germany) at some schools (mostly schools with students years 11 to 13) also two-weeks timetables are used.
hmm... I am not 100% sure if this is always needed, but I know that at some schools also some teachers have two-weeks not available times. For example because they work at an other school that uses a two-weekly timetable or because they have every 14 days a further training. So i think it should be also possible to set the teachers not available constraint also for odd or even days. Will that also be possible in that mode?

[Liviu Lalescu]

Hmm... Volker, then maybe nomad's approach from this topic: https://lalescu.ro/liviu/fet/forum/index.php?topic=351.0 would be better?

So, consider the FET days displayed to the user = 2*5 (or 2*6), and internally double the weekly activities and add min+max days between them = 5 (or 6), same starting hour, and occupy max 1 different room?

The advantage and in the same time disadvantage: the gaps (for each teacher or students set) will be summed for two weeks. If you say for instance max 3 gaps per FET week, teacher T might have 3 gaps in odd and 0 gaps in even weeks.

[Liviu Lalescu]

Thinking again, maybe 6 new constraints available only in this mode will solve the first approach: teacher/students set/room not available times odd week, and then even week.

The first approach seems to me more efficient and you will see only a week, not two, which is too large.

Edit: also constraints break odd week and break even week. And we also need to double the rooms (internally).

[Volker Dirr]

Yes, maybe like that. I am also not sure. I think it is the best if we find a guy that need this variant (now) and helps also suggesting and testing a bit. So we can see better how it will work with real data sets.
So, if you need a version like that. Please write answer here.

[Liviu Lalescu]

I have a good file from a user, which I hope I can modify to test.

What do you think, if we manage to do this, will it be FET-6.23.0 or FET-7.0.0?

[Liviu Lalescu]

I have thought of this problem in the last days.

What I am thinking right now:

1) Double each students set and each teacher. If we have for instance year StA and teacher T, make them "1 StA" and "2 StA", and "1 T" and "2 T".

2) 1 will stand for odd weeks, and 2 will stand for even weeks.

3) Each "weekly" activity will have double the students sets and teachers. If we have A (StA, T), it will become A (1 StA, 2 StA, 1 T, 2 T). "Odd" activities will have from A (StA, T) -> A (1 StA, 1 T) and "even" activities will have from A (StA, T) -> A (2 StA, 2 T).

4) This is the main drawback and major problem: we cannot double the rooms, because of the vast variety of space constraints, and because weekly activities should occupy two rooms (1 R, 2 R). I see as a potential solution / workaround to simply ignore the rooms of "even" activities. This might be acceptable in practice.

Please let me know your opinion on the trick / workaround we could use about space constraints (point 4 above).