Hello
@dimzev!
Of course I agree with Liviu that the constraints he mentions solve your problem. The problem you describe occurs in most cases in Greek schools with the activities of the Language and Literature Teachers. Most of the time, these teachers have many activities with the same students group. For example, the same teacher might teach the same students group Modern Greek Language, Modern Greek Literature, Ancient Greek Language, Ancient Greek Literature in Translation and History. This is a total of 10-11 hours per week for the Greek Gymnasium. Since I faced this problem in the past, I personally preferred not to add the constraints Liviu mentioned, but to add the activities in a different way. For example, you could add for this student group and this teacher the following activities:
1) For the classes of Modern Greek Language & Modern Greek Literature, add an activity with Subject = Modern Greek, split = 4, duration = 1, min days = 1, weight = 100%. Or you could add an activity with Subject = Modern Greek Language, split = 4, duration = 1, min days = 1 and then modify the two subactivities of this activity by changing the subject from Modern Greek Language to Modern Greek Literature.
2) You could follow a similar approach for Ancient Greek.
3) For the class of History add an activity with subject = History, split = 2, duration = 1, min days = 1, weight 100%.
The above workout should ensure that there is no day with more than 3 hours of this teacher with this specific students group. Of course this approach is not the only valid one.
The reason I preferred this approach, is that when adding constraints, and in case the timetable becomes very difficult (or sometimes impossible) it's harder to find out the problem (in this case you should search in a larger number of constraints).
Vangelis.