teachers preferred times

[silvia]

hello,
I guess I'm not in time for another suggestion, but I'll try for the future.
Would it be possible to add a time constraint for teachers saying preferred times? I don't mean available times. Sometimes a teacher says: I'd like not to have classes 1st one in the morning, or I'd like not to have classes more than one afternoon. But sometimes a teacher says: I'd prefer to start at first time in the morning. Is that possible?
Thanks

[Liviu Lalescu]

It seems very difficult.

Added in TODO.

[Volker Dirr]

I'd prefer to start at first time in the morning.

In my opinion it is not needed, just ask why he/she want that?

case 1:
If you have "bad" luck the guy will say "i can concentrate better in the morning." Then say: "So you can't concentarate in late hours? ok. i will set that late periods not available." or maybe say "students must also concentrate in late hours. I will reduce your total number of working periods per week if you have concentrating problem in late hours (so he work less / earn less money)."

case 2:
Maybe he say "because my children are in the kindergarden and come home at 13:00". Then it is easy: just set last periods to not available.

case 3:
...

it is always the same: just ask about the reason and you will see that the real reason will be done witha a not available constraint.

[silvia]

oh well, these cases are usually the same. The students are fresher first time so the teachers who don't mind beginning first time (because they don't have children to take to nursery, or don't live far from school) will prefer to begin early.

Not allowing last hours is not a solution, because I have to specifically prohibit one last hour, one specific day. What if I get more difficult (or worse) timetables because of this?
Maybe a solution would be to allow teachers time constraints (teacher not available) with a weight less than 100%

this would mean: I prefer not class in last hour, in a 90%, but I can do last hours if necessary.

[Volker Dirr]

in my opinion only the 100% weight is needed, because he has problems to get a nursery or he doesn't has that problem.

of course you can't disallow all last periods to teachers. but you also can't set preferd first periods to all teachers, because you have more teachers then groups. So my "problem" is the same as "your" problem.
there is always the same number of first periods (equal to the number of groups) if you use a must begin early constraint. And there are always the same (less if the tables are not 100% filled) number of activities in the last period. you can't reduce the number of first or last activities by such an constraint. there are always teachers that much teach in that hours. (if students are not allowed to have gaps).

in my opinion the solution is using a good max and min hours daily and a good max gaps constraint to teachers. good mean with 100%.

[Liviu Lalescu]

oh well, these cases are usually the same. The students are fresher first time so the teachers who don't mind beginning first time (because they don't have children to take to nursery, or don't live far from school) will prefer to begin early.

Not allowing last hours is not a solution, because I have to specifically prohibit one last hour, one specific day. What if I get more difficult (or worse) timetables because of this?
Maybe a solution would be to allow teachers time constraints (teacher not available) with a weight less than 100%

this would mean: I prefer not class in last hour, in a 90%, but I can do last hours if necessary.

But you can add constraint activities preferred time slots for a teacher (you'll get a warning, but ignore it :-). You can add any weight there. It is like a not available, with any weight and gaps counting.

[silvia]

hey, that is good news, liviu! I'll try that.

Volker, students are not allowed gaps, but I have 55 teachers who give more or less 18 hours a week each, and 18 groups, with 30 hours a week, so yes, I can allow some teachers not to start at first hour, and some teacher to start at first hours. Strange Spanish public school system, I know  

[ßingen]

But you can add constraint activities preferred time slots for a teacher (you'll get a warning, but ignore it :-). You can add any weight there. It is like a not available, with any weight and gaps counting.

I had the same problem as Silvia (same school system), so I'm going to try this solution...

  ßingen.