OptaPlanner/Timefold - Timetable generation with repeated lessons

Question

I am using the documentation of timetable generation quickstart at https://timefold.ai/docs/timefold-solver/latest/quickstart/spring-boot/spring-boot-quickstart.html#springBootJavaQuickStart.

As per the quickstart, If a subject is taught multiple times per week by the same teacher to the same student group, there are multiple Lesson instances that are only distinguishable by id. What I understand here is that, if a teacher is teaching Chemistry for Grade 10, then as part of the inputs I need to list out how many times the teacher will taking that class in a week. This looks counterintuitive. I would like the planner to solve and give me a timetable along with how many classes can the teacher take per week without having conflicts, and all timeslots of the week are filled.

Any pointers in resolving this is highly welcome.

Answer 1

The solver assumes you know how many teachers you have, and how many classes they have to teach. It will crunch that data, and give you a good solution for assigning available teachers to the required amount of classes.

If, however, you're asking how many teachers you'll need to teach X amount of classes, or how many classes can possibly be taught by Y amount of teachers, that is a different problem. The solver can probably be adapted to answer that question - keep adding teachers/classes until it finally finds a feasible solution. But that is besides the point.

The key point here is: The solver is not a prediction engine. If you don't know ahead of time the amount of classes that need to be taught, I'd argue you either don't have a planning problem, or it is a different kind of problem than employee scheduling.