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FET Support (English) => Get Help => Topic started by: Chafik Graiguer on September 13, 2008, 04:10:02 PM

Title: About min n days between activities constraints
Post by: Chafik Graiguer on September 13, 2008, 04:10:02 PM
Yet another question
as I montioned before
groups have 4 hours of subject fr
I dont want FET to schedule 2 consecutive hour in one day and two other consecutive hours on another day: 2+2

rather I want a disttibution like this:
1+1+2 (order doesnot matter)
or 1+1+1+1
this can be called "subject spread"
in other words, groups have to study subject fr for at least 3 days
Title: Re: About min n days between activities constraints
Post by: Liviu Lalescu on September 13, 2008, 04:50:35 PM
This is taken care of by FET.

If weight is 95% min days 1 with 4 activities, then in approx. 5% of cases you might get 2 activities in the same day. In approx. 5%*5%=0.25% of cases, you get 2 activities in a day and other 2 activities in a day. So, practically you will not obtain 2+2.

If you raise weight to 99% or 99.75%, the chance is even less that you get 2+2. But I advice to raise weight after obtaining a timetable with 95%.

You will never obtain 3+1 or 4, because of FET operation.
Title: Re: About min n days between activities constraints
Post by: Chafik Graiguer on September 13, 2008, 04:56:21 PM
ok, but what if the disrtibution: 2+1+1 is more desirable but not a necessity !!?
likewise for a subject with 5 hours per week, a distribution like this 2+2+1 is more desirable but not a necessity !!?

the same apply for a subject with 7 hours per week: 2+2+2+1

for the last case, I can input directly: 2+2+2+1
like this:

Activity:
- split into activities per week 3
duration 2

+Activity:
- split into activities per week 1
duration 1

But I wish to give FET more freedom/flexbility    :)
Title: Re: About min n days between activities constraints
Post by: Liviu Lalescu on September 13, 2008, 05:05:07 PM
FET considers 1+1+1+1 more desirable than 2+1+1, I cannot change that. If you want 2+1+1, then input activities like that: 3 sub-activities, with duration 2, 1 and 1.

Nobody until now said that 2+1+1 is better than 1+1+1+1.
Title: Re: About min n days between activities constraints
Post by: Liviu Lalescu on September 13, 2008, 05:09:00 PM
Quote
the same apply for a subject with 7 hours per week: 2+2+2+1

for the last case, I can input directly: 2+2+2+1
like this:

Activity:
- split into activities per week 3
duration 2

+Activity:
- split into activities per week 1
duration 1

No, you are wrong. Split A into 4 components, durations 2, 2, 2 and 1.

Please do not add more components for an activity than the real number of days per week. FET is slower/worse this way and you may not find a solution. The correct way is to add maximum n days per week components for an activity (FET warns otherwise).
Title: Re: About min n days between activities constraints
Post by: Chafik Graiguer on September 13, 2008, 05:25:23 PM
QuoteNo, you are wrong. Split A into 4 components, durations 2, 2, 2 and 1..
So I should restart input from the beginnig !!!


QuotePlease do not add more components for an activity than the real number of days per week.
for the subject "fr" with 4 hours per week (knowing that 2+1+1 is more desirable )
what is better for FET:
split A into 3 sub activities, durations 2, 1 and 1
or
split A into 4 sub activities, durations 1, 1, 1,  and 1 hoping that FET will do 2+1+1 whenever possible  ?

it is a dillema :
in one hand, I think FET will prefer 1, 1, 1, and 1 in order to eventually fill gaps in the student's timetables -gaps are usualy 1 hour long)
in other hand 2+1+1 is more desirable
Title: Re: About min n days between activities constraints
Post by: Liviu Lalescu on September 13, 2008, 05:28:36 PM
I am sorry.

Please try to make a file with 2+1+1 and see if you get solutions. I think you will.