Structure of Students' data

[aliponte]

As far as I've seen, FET uses just three levels in the graph that is representing the students' data: year, group and subgroup.
Is that true? Or is it possible to define a group "A" and then use it as a subgroup of another group "B"? This would allow for a structure of arbitrary depth.

Thank you for responding
aliponte

[Liviu Lalescu]

Only three level. A year can contain only groups, and a group can contain only subgroups (you can test practically to add a group in another group, and FET will tell that it is impossible).

Your idea is nice, but now it is too late to implement it.

But you don't need many levels. Even with only two levels you can manage any structure. A subgroup must be the smallest independent set, and you can define any groups, containing any subgroups. With three levels (as it is in FET), it is a bit easier than with two.

[aliponte]

Thank you for your answer, Liviu

Let me summarize what I've understood:

The hierarchy of FET's students' set structure comprises exactly three levels: year, group, subgroup.

1)
A year is a union of not necessarily disjunct groups. This means:
Provided that

year Y := union(group Y1, group Y2)

an activity A1 of Y1 cannot be allocated at the same place in the timetable as an activity A2 of Y2.

2)
A group is a union of disjunct subgroups.

This means: Provided that

group G := union(subgroup G1, subgroup G2)

an activity A1 of G1 can be allocated at the same place in the timetable as an activity A2 of G2.

[Liviu Lalescu]

Thank you for your answer, Liviu

Let me summarize what I've understood:

The hierarchy of FET's students' set structure comprises exactly three levels: year, group, subgroup.

1)
A year is a union of not necessarily disjunct groups. This means:
Provided that

year Y := union(group Y1, group Y2)

an activity A1 of Y1 cannot be allocated at the same place in the timetable as an activity A2 of Y2.

2)
A group is a union of disjunct subgroups.

This means: Provided that

group G := union(subgroup G1, subgroup G2)

an activity A1 of G1 can be allocated at the same place in the timetable as an activity A2 of G2.

Point 2 is wrong.

Let me explain again: you have years, groups and subgroups. Each pair of subgroups must be independent/disjunct. Groups can contain subgroups, and 2 groups can share subgroups. Years can contain groups, and 2 years can share groups or subgroups (via groups).

Please divide automatically a year by more than 1 category (2 or 3) and check the structure. You'll see better. There are also some words in the FAQ.

Example: Y1 (G1 (S1, S2, S3), G2 (S1, S4)). Then G1 and G2 are overlapping. Activity A1(G1) and A2(G2) cannot be in the same time (because otherwise subgroup S1 is "overwhelmed").

[Volker Dirr]

Also point 1 is wrong if both groups in the same year have different subgroups.