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FET Support (English) => Get Help on Your Input File => Topic started by: robbo on June 10, 2023, 01:19:25 PM

Title: Does order matter for split activities?
Post by: robbo on June 10, 2023, 01:19:25 PM
I have a lot of 6-lesson activities. I use sub-activities to change the teachers for some of them. Does the order matter? Some of the teachers are part-time and it isn't finding a solution.
Title: Re: Does order matter for split activities?
Post by: Volker Dirr on June 10, 2023, 01:31:07 PM
You mean you have an activity with total duration 6 and split it for example like this:
2-2-1-1
and the other time you split it like this:
1-1-2-2

In normal case the order doesn't matter.

Except if you use a constraint like "subactivities preffered starting time", since in constraints like that you choose the component number (split index). So if you choose split index 1 in such a constraint, then it will affect the first subactivity with duration 2 in the first example, but in the second example it will affect the subactivity with duration 1.
Title: Re: Does order matter for split activities?
Post by: robbo on June 10, 2023, 01:35:54 PM
Thank you for the reply. I split them like this, worst case:

1/6 Teacher A
2/6 Teacher A
3/6 Teacher B
4/6 Teacher B
5/6 Teacher C
6/6 Teacher C

Most blocks are split 3:3.

I use activity tags to group them and then constraints to say tags mustn't overlap.

So, if A works Th, Fr, Sa and B works M, Tu, W would I be better ordering the sub-activities to put C first and A last?
Title: Re: Does order matter for split activities?
Post by: Volker Dirr on June 10, 2023, 01:48:58 PM
ah. Ok. In fact it is nearly the the same answer (read carefully, i modified a bit):

In normal case the order doesn't matter.

Except if you use a constraint like "subactivities preffered starting time", since in constraints like that you choose the component number (split index). So if you choose split index 1 in such a constraint, then it will affect the first subactivity with teacher A in your example, but with an other order it will affect the subactivity with an other teacher (C).
Title: Re: Does order matter for split activities?
Post by: robbo on June 10, 2023, 01:57:32 PM
Thanks. So, I am only using tags, say:

U6-A
U6-B
U6-C
U6-D
U6-X

Then one constraint that says they must not overlap.
Title: Re: Does order matter for split activities?
Post by: Volker Dirr on June 10, 2023, 02:01:48 PM
So if you swap a teacher, do you also swap the tag?
If you also swap the tag, then the order doesn't matter.

If you swap the teacher, but not the tag, then it might matter.
it is depeding on what constraints you use. Only not overlapping tags constraint? Then the order doesn't matter.
If you use different preffered time constraints with that tags, then it matters.
In fact in that case it is not the order that matters, the "correct" reason is that an other differnt tag is connected to an other teacher. So it matter in that case.
Title: Re: Does order matter for split activities?
Post by: Volker Dirr on June 10, 2023, 02:05:47 PM
Please read my previous answer once again. I just modified it.
Title: Re: Does order matter for split activities?
Post by: robbo on June 10, 2023, 02:47:24 PM
Hi

All six activities have the same tag. Is it okay if I email my input file, please? I can't see why it won't solve. :(
Title: Re: Does order matter for split activities?
Post by: Volker Dirr on June 10, 2023, 04:07:47 PM
I haven't much time at the moment (i have much time in 2 weeks), but i can have a quick look now. So you can email me.
Title: Re: Does order matter for split activities?
Post by: robbo on June 14, 2023, 12:18:03 PM
Thanks. Sorry for delay in replying. It turned out I wasn't allowing enough time for it to find a solution. 9-16hrs needed!
Title: Re: Does order matter for split activities?
Post by: Liviu Lalescu on June 14, 2023, 04:38:13 PM
Wow! That is something (though not the record).

If you have more cores, you can generate multiple with nThreads=n_cores_you_have, and FET might find a solution faster.