Time constraints (teachers) less then 100%

[Steve_DR]

Hi all!
First time on this forum as I recently downloaded FET and am trying to implement it for a secondary school  (about 1000 students, 100 teachers). However, I'm confused on the 'Teacher constraint' : it says (and I quote the manual)

"Time constraints (teachers) → A teacher is not available
<...>
It might happen that teachers, students or rooms are not available.
This constraints must have weight 100%."

Does this mean it is not possible to add a preference on a teacher's availability like "Teacher A would love to have all Thursday off" (should the timetable have a valid solution. If there is no solution possible : too bad for him, he will have to teach on Thursday). I tried adding a weight below 100%, but it is not accepted.

Sincerely, Steve

[Liviu Lalescu]

Hello!

If you want to use weight <100%, use constraint activities preferred times (time slots or starting times), selecting only the teacher and neglecting the warning. The gaps will be counted (unlike the not available constraint).

But this will not solve for the whole day, I think. I think that you need to add an activity with duration = number of hours per day and preferred times not on Thursday (X or red on Thursday with a weight <100%). This activity must be placed on another day if on Thursday it is impossible, so teacher T must have a free day if you use this approach.