énigma!

[Benahmed Abdelkrim]

Hello!

here is a problem:

a school has 20 sets of students,
  4 sets take their course in another school (annex),
2 sets of students from the first schools do not have fixed rooms.
Some teachers must move between the 2 schools (buildings) to satisfy their activities.
teachers must work exclusively in the morning or afternoon in a school or other, but not both at the same time (morning or afternoon)

this problem was easily solved using space constraints;
max buildings changes per day for a teacher,

because we treat these 2 schools in FET as 2 buildings only.

but unfortunately it has these 2 sets of students who do not have a fixed room, and who must move between rooms every 2 hours, this fact forces us to treat each room as a building to satisfy this condition and allow us to use the constraint of space;
min gaps between building changes for a students set.

but for teachers the number of buildings has increased, which prevents us from using the space constraint described above.

if there were in FET the constraint of space:
min gaps between room changes for a students sets
this problem will be solved easily !

Is there another way to solve this problem?

[Volker Dirr]

I fear such a new constraint will fail as soon as the school has got a special room and students have got 1 hour(activity) in that special room.

So if you have got for example 1 hour in the gym, 1 hour in music room, 1 hour in art room, 1 hour in physics room, 1 hour in computer science room, ...
All that mean the timetable will fail, since the students won't be able to swap the room without a gap at a time where a gap is not allowed.

So you are sure that school haven't got a special room? Even not gym?

Since only 2 classes have got that problem you might place that 2 one manually first (by preferred time slots constraint). After that you let FET generate the rest of the classes automatically.

[Liviu Lalescu]

if there were in FET the constraint of space:
min gaps between room changes for a students
this problem will be solved easily !

Hello!

Why aren't you using the Morocco version?

I could try to make such a customization to have students min 1 gaps between room changes. But not in the official.

[Benahmed Abdelkrim]

I fear such a new constraint will fail as soon as the school has got a special room and students have got 1 hour(activity) in that special room.

So if you have got for example 1 hour in the gym, 1 hour in music room, 1 hour in art room, 1 hour in physics room, 1 hour in computer science room, ...
All that mean the timetable will fail, since the students won't be able to swap the room without a gap at a time where a gap is not allowed.

So you are sure that school haven't got a special room? Even not gym?

Since only 2 classes have got that problem you might place that 2 one manually first (by preferred time slots constraint). After that you let FET generate the rest of the classes automatically.

if the time table of the students is not completely filled, which is the case in most schools, I think that it is possible even with 1 hour in special rooms provided that these students can start the second hour in the day.
there is also a possibility to allow these activities to be consecutive, I think it could be automatic with FET.

[Benahmed Abdelkrim]

if there were in FET the constraint of space:
min gaps between room changes for a students
this problem will be solved easily !

Hello!

Why aren't you using the Morocco version?

even using the Moroccan version, it does not solve the problem.

I could try to make such a customization to have students min 1 gaps between room changes. But not in the official.

I think this new constraint will also be useful for the official version of FET

[Volker Dirr]

if the time table of the students is not completely filled, which is the case in most schools, I think that it is possible even with 1 hour in special rooms provided that these students can start the second hour in the day.
there is also a possibility to allow these activities to be consecutive, I think it could be automatic with FET.

Here (Germany) (nearly) all students (below year 11) must come to the first hour already and they normally always have got 100% filled tables. Not filled students tables are the exception.
Students at my school (year 5 to 10) have got at least 8 hours in special rooms (for example in year 5:  2 hours physics, 1 hour biology, 2 hours art, 2 hours sports and 1 hour swimming).
And a maximum of 12 hours (for example in year 10: 7 hours in science rooms, 3 hours sports and 2 hours art and music).

So such a constraint will be totally impossible at (all?) German schools.

[Benahmed Abdelkrim]

for 2 hours activities this is not a problem.

but for the activities of 1 hour we can make them consecutive even if the timetable is completely filled.

which could make this constraint possible.

[Volker Dirr]

You are sure you can do that with ALL special rooms? Don't forget that the trick with soming to the second hour to school (or leaving already 1 hour early) will not work always, since it mean you can't use the special room in the first and the last hour. So you will get a problem/limit of students AND room!

[Volker Dirr]

Ah... Maybe an other very easy solution without any problem to special rooms and without a new constraint:
Give the 2 classes that need to swap the rooms only activities with duration 2.

[Benahmed Abdelkrim]

You are sure you can do that with ALL special rooms? Don't forget that the trick with soming to the second hour to school (or leaving already 1 hour early) will not work always, since it mean you can't use the special room in the first and the last hour. So you will get a problem/limit of students AND room!

the problem of room limit can be solved easily if we use the time in a correct way.
I even solved complicated time tables with FET or there were 10 sets of students who did not have a fixed room.

[Volker Dirr]

if i can't use the special room in the first and the last hour it mean it is unused at least 10 hours per week. With the custom versions even 20 hours per week. Many school timetables will be impossible by that since they need the room more times.

I suggest to place that 2 classes manually and let FET do the rest. The big advantage will be that you won't get room problem by that.

[Benahmed Abdelkrim]

Ah... Maybe an other very easy solution without any problem to special rooms and without a new constraint:
Give the 2 classes that need to swap the rooms only activities with duration 2.

yes absolutely what I always do!
but the problem that arises, when teachers have to work in different buildings in the morning or afternoon exlusively.

[Volker Dirr]

But that problem won't be solved by the suggested constraint.

That is mainly a problem of the activity planning (not of the timetabling). I can even do very easily impossible timetables by such an activity planning. But you can also simplify the problem by a good activity planning.

[Benahmed Abdelkrim]

if i can't use the special room in the first and the last hour it mean it is unused at least 10 hours per week. With the custom versions even 20 hours per week. Many school timetables will be impossible by that since they need the room more times.

I suggest to place that 2 classes manually and let FET do the rest. The big advantage will be that you won't get room problem by that.

yes 2 classes is easy, but when there are more classes, the task gets more complicated.
do this with FET automatically makes the task very easy.

[Volker Dirr]

ok. so the problem is currently solved.
We can rethink about this problem as soon there is a school with more than 2 classes. I bet it will be impossible at most schools because of the special rooms.