2 consecutive real days?

[Benahmed Abdelkrim]

I would need also the solution with the teacher working in two consecutive real days

Sent it by email just now

[Benahmed Abdelkrim]

Benahmed, wouldn't it be better: "Teacher(s) max three consecutive days"? Because 4 consecutive half-days might be tiring, even if like this: RD1-evening, RD2-morning, RD2-afternoon, and RD3-morning?

no, I think it's not a good name...
think about solutions where the days are not consecutive.
for example:
Sunday morning - Sunday afternoon - Monday afternoon.
these days are not consecutive but the solution is good.

[Liviu Lalescu]

Sunday morning - Sunday afternoon - Monday afternoon.
these days are not consecutive but the solution is good.

It would be accepted by my proposal, because there are only 2 consecutive days (Sun-M, Sun-A). I accept even 3 consecutive days, but not 4. I refer to days as half-days.

I mean from your proposal with no 2 consecutive real days to reject this: RD1-A, RD2-M, RD2-A, RD3-M, because there are more than 3 consecutive days.

[Benahmed Abdelkrim]

I think the last name is GOOD. "teacher(s) no two consecutive real days", or this name: "teacher(s) must not work two consecutive real days"

[Benahmed Abdelkrim]

I mean from your proposal with no 2 consecutive real days to reject this: RD1-A, RD2-M, RD2-A, RD3-M, because there are more than 3 consecutive days.

I think this situation is acceptable to our teachers. what is not acceptable is the 2 consecutive real days.

[Liviu Lalescu]

Hmm...:

1) I still don't like the name "Teacher(s) no two consecutive real days". The user might understand each real day must be isolated to the left and right completely by two empty real days.

2) I consider max 3 consecutive half-days more useful. Because the teacher will be exhausted by coming afternoon, then whole day, then morning, isn't it?

3) In your file I see that actually teacher H6 has 5 half-days in a row. So maybe we would need to add a constraint "Teacher(s) max four consecutive days" (maybe that is why he was unsatisfied).

Of course I admit you are better than me at knowing the necessities of the teachers, but this is my opinion. Maybe you could ask other users about this. We need to know the best formula before adding a new constraint.

[Benahmed Abdelkrim]

I consider max 3 consecutive half-days more useful. Because the teacher will be exhausted by coming afternoon, then whole day, then morning, isn't it?

Well I agree with you. I think this is a good solution. I am convinced. Thank you

[Liviu Lalescu]

I consider max 3 consecutive half-days more useful. Because the teacher will be exhausted by coming afternoon, then whole day, then morning, isn't it?

Well I agree with you. I think this is a good solution. I am convinced. Thank you

Good!

The file you sent me was your final file? Because I would like to make sure I test with the most difficult file. And I will add for all teachers max 3 consecutive days?

[Benahmed Abdelkrim]

I alleviated some constraints to make it easy. I will send you my last file by email.

[Liviu Lalescu]

Thank you! Please send the file, the data_and_timetable, and the random seeds if you still have it.

The previous emails were for the same easy file (file, data_and_timetable, random seed)?

[Benahmed Abdelkrim]

The previous emails were for the same easy file (file, data_and_timetable, random seed)?

Yes, of course.

[Hiba Hadi]

Great!

Or: Teacher(s) don't work in two consecutive real days. Hmm... but either your way (teacher(s) no two consecutive real days) or my way it is not clear. Because the user might understand that the teacher is allowed a real day and the two real days before and after must be both totally free....

Please provide me with your file, for testing (when and if I'll do it). I would need also the solution with the teacher working in two consecutive real days. And if your file is too difficult (hours to solve), send me a modified one to solve in ~20 minutes.

OK, Hiba Hadi, I took notice of your comment!

Thank you 🙂

[Benahmed Abdelkrim]

Benahmed, wouldn't it be better: "Teacher(s) max three consecutive days"? Because 4 consecutive half-days might be tiring, even if like this: RD1-evening, RD2-morning, RD2-afternoon, and RD3-morning?

Dear Liviu;
I have thought about the idea max 3 consecutive days, and I fear that this constraint is for certain difficult files powerful, and can even lead to impossible timetables unless accepting the following situation: RD1-A, RD2-  M, RD2-A, RD3-M.  this situation is acceptable as long as we do not have 2 real consecutive days. what do you think?

[Liviu Lalescu]

Dear Benahmed,

Yes, I just finished a sketch of this constraint max 3 consecutive days for all teachers and indeed your file seems clearly impossible (max 500 activities placed after ~12 minutes generating on 8 threads).

The problem with your initial suggestion is that it is very specialized, we cannot find a perfect name for the constraint, and it is not implementable perfectly. That is why I would not like to add it for now. The best solution I can think of is for you to generate multiple and choose a solution which avoids this situation.

I will add your suggestion in the TODO and think on it the next days.

I am so sorry!

We can talk on this, of course.

[Benahmed Abdelkrim]

I have thought about this question, and I think the best way to make the file solvable is to accept my suggestion expressed in my previous comment.