Minimum days per week for students or Students must come on a day

Started by V Paul C Charlesraj, January 05, 2018, 08:06:48 AM

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V Paul C Charlesraj

I have a situation. I have enforced minimum and maximum hours in a day as well as maximum days per week for students. This results in empty days. But is it possible to control this empty days does not fall on a specific day. For example: we expect all the students report to school on Thursday. How to enforce this?
Thanks.
Paul

Volker Dirr

i think the easierst will be to add activities with subject "report" to students groups and use a constraint that this activity must be on thursday.

An other variant might be using the max occupy constraint, but the disadvantage will be that you need to exactly count the students hours (and you always need to modify that constraint as soon as the number of student hours change). See "help" in the max occupy constraint.

Liviu Lalescu

Volker is referring in his second variant to the constraint of type activities occupy max time slots from selection. Yes, it might be a bit difficult to use it.

But I am not sure if the first proposal of Volker is applicable.

V Paul C Charlesraj

Thanks for your suggestions.  Volker's first suggestion would not work since there shall be some activities scheduled not just reporting.  I need to checkout the second one.

V Paul C Charlesraj

Minimum number of days in a week for all students  shall do the trick but I could not find such constraint for students but there is one for teachers.

Liviu Lalescu

Quote from: V Paul C Charlesraj on January 05, 2018, 01:52:18 PM
Minimum number of days in a week for all students  shall do the trick but I could not find such constraint for students but there is one for teachers.

Hmm, yes, you touched a sensitive point :(

It is very difficult to add this constraint implemented correctly (perfectly) for the students, such as we did for the teachers. It might be easier to implement it not perfectly, but I would not like to add such a thing in the official FET.

I will add your suggestion in the TODO (students min days per week).

Implemented perfectly means to take care of the interaction with the other constraints.

Volker Dirr

you can maybe do it indirectly.
for example by reducing the max number of hours per day they will be forced to have more days per week.

V Paul C Charlesraj

Quote from: Volker Dirr on January 05, 2018, 02:10:28 PM
you can maybe do it indirectly.
for example by reducing the max number of hours per day they will be forced to have more days per week.

I have tried all those things but failed to get a solution.  I have never used the other constraint, max occupy. Let me try.

Liviu Lalescu

Quote from: V Paul C Charlesraj on January 05, 2018, 01:52:18 PM
Minimum number of days in a week for all students  shall do the trick but I could not find such constraint for students but there is one for teachers.

Funny idea: If you don't have a complex students' structure you might consider a real students set = a FET teacher, and have in FET only teachers, and add a constraint teacher min days per week for each real students set :)

V Paul C Charlesraj

Quote from: Liviu Lalescu on January 05, 2018, 02:19:25 PM
Quote from: V Paul C Charlesraj on January 05, 2018, 01:52:18 PM
Minimum number of days in a week for all students  shall do the trick but I could not find such constraint for students but there is one for teachers.

Funny idea: If you don't have a complex students' structure you might consider a real students set = a FET teacher, and have in FET only teachers, and add a constraint teacher min days per week for each real students set :)
Sorry, this would not work.

pervezshaikh

 V Paul C Charlesraj!

Write down few activities, which you want on Thursdays. Use constraint "An activity has a preferred starting time" for one of the listed activities. First hour would be a good choice on Thursday. Afterwards use "A set of activities has same starting day (any hour)" for all listed activities. I hope it will work.