I removed the 100% restriction for min hours daily for all teachers and for min hours daily for all studentes, compiled FET 5.30.2 from sources, and tested with my timetable. I have to say that I like the resulting timetable more. I used 99% weight for 2hours/day for all students, and I got a timetable much suitable for our needs.
I don't understand why some constraints require 100% weight (except for the basic time/space ones), but maybe there could be an advance setting to allow less that 100% weights for them (like the Allow empty days) so that people can test with them.
I meant the "exact" with respect to how FET "sees" the week. In my case, we have a FET timetable of 10 days (5 days/week x 2 weeks). If for activities A and B, I use "Min 5 days between two activities" and "Max 5 days between two activities" and "Two activities have same hour", the I get them scheduled in same week day, at same time, in both odd and even week.
Obviously, 5 here is related to my timetable setup. If I would have classes on Saturday, then I would have 12 days FET timetable and use 6 days in these restrictions.
Could you add an extra field for subjects and teachers to allow for a short name/abbreviation of it? For example, for a subject called "Classical literature" a short name could be "CL" or "C-101". Then the print timetable features would allow to print the short names (i.e. compact timetable) or long names (i.e. normal timetable)
A constraint "Exact N days between activities" would imply "Min N days between activities" AND "Max N days between activities". I use these two constraints simultaneously in order to force two activities to be scheduled in same week days (in an odd/even timetable).
I have a setup with 1500 activities spanning over 2 weeks (odd/even scenario). If I don't use the min hours per day for all teachers constraint I get a timetable in less than 1 minute. If I use that constraints FET doesn't finish even after 30 minutes. I would like that most teacher have a minimum hours per day constraint set, but I would like to permit a few exceptions (when needed). I could probably do by using a constraints for each teacher, but that is too complicated (and besides I don't know before hand which teacher should have it and which should not).
So, my question is: Is it possible to have 0-100 weights for the constraint "Minimum hours per day for all teachers" (instead of the mandatory weight of 100%). Would that break FET algorithm?