Too few hours and too few slots

flossed.org · July 29, 2010, 05:28:20 PM

I have been making progress with a k-12 schedule; yesterday got great help on setting up constraints.

Today, I thought I had set things up well, but when I tried to make a schedule ran into two kinds of errors, too few hours and too few slots.

Looking at the number of slots, I see that, yes, indeed, I do have too few. For example, I need 121 but have 90.

ERROR MESSAGE caused by attempting to generate a schedule:

"Cannot optimize for subgroup Sr Kg Automatic Group Automatic Subgroup, because the number of hours for subgroup is 120 and you have only 90 free slots from constraints students set not available and/or break. Maybe you inputted wrong constraints students set not available or break or the number of hours per week is less because of a misunderstanding"

However, I cannot understand why the units of time would limit the number of activities I can put within a time-period. Somehow I have set up this limitation, but I don't know where.

Slots are the division (lowest common denominator of time) which you all helped me set up yesterday. Are the number of available rooms the key? Or teachers? I removed all rooms and got the same error.

Have I given you enough of a picture for you to guess what I might be doing wrong?

Thanks in advance,

David

Liviu Lalescu · July 29, 2010, 05:33:23 PM

The year has 120 working hours (slots, periods) per week, which is the total duration of all activities with this year.

The year has 90 free slots (hours, periods) per week, which all the slots minus breaks and not available.

120 is not <= 90 (so, this is wrong).

Maybe you could attach your input file.

flossed.org · July 29, 2010, 05:58:22 PM

Thank you. Yes, I'm very clear that 90 is less than 120 ;-), but I'm looking for a clue to where I screwed up.

I'll upload my file just in case. Thanks for your amazing help.

David

Liviu Lalescu · July 29, 2010, 06:55:52 PM

QuoteThank you. Yes, I'm very clear that 90 is less than 120 ;-), but I'm looking for a clue to where I screwed up.

I'll upload my file just in case. Thanks for your amazing help.

David

I saw the file. There is a constraint students set not available for the year "Sr Kg", leaving out only 90 allowed slots. In the activities, I select the filter for that year. The total duration is 120.

Probably you swapped allowed slots with not allowed slots in not available constraint. Add X for not allowed slot. 210-90=120, that is why I think you made this mistake.

PS: Please upgrade to latest FET, it is better.

flossed.org · July 29, 2010, 07:02:54 PM

Thank you. I will look at the constraints again.

tevi · July 29, 2010, 07:04:05 PM

Exactly,

In time constraints (students) you have for Sr Kg only 90 slots (green cells), but in activities you have more than 90. You can see it in Statistics Students.

You must to check the activities for this year. Perhaps they have too much maths or arts or languages...

Liviu Lalescu · July 29, 2010, 07:08:41 PM

QuoteExactly,

In time constraints (students) you have for Sr Kg only 90 slots (green cells), but in activities you have more than 90. You can see it in Statistics Students.

You must to check the activities for this year. Perhaps they have too much maths or arts or languages...

Green/red colors are shown in case you enable GUI colors in the FET settings -> interface menu.

flossed.org · July 30, 2010, 04:26:42 AM

I've got the colors, and, unfortunately, I've verified the time constraints. There are too few time slots. If a slot is created by combining an available teacher and students, and I've put in no students, how does fet know there aren't enough slots --

I'm getting that I have to add more slots during the same time period ... students don't all take the same course at the same time. Do I have to add some kind of subgroup to create the needed slots?

Do I have to specify # of students? If I have 100 students and 100 teachers, and 100 rooms, I could teach 100 courses at the same time, right? So, this error -- not enough slots -- is saying ... I don't have enough what?

flossed.org · July 30, 2010, 05:21:47 AM

I have simply begun lowering the number of required meetings per week and that seems to have cleared the barriers.

Now on to normal problems such as getting periods to start at reasonable parts of the day ... preferred starting times, I suppose? How to keep them to a minimum is the question.

It's great that FET lets you test after each change.

Thank you.

tevi · July 30, 2010, 01:35:18 PM

Quote
I'm getting that I have to add more slots during the same time period ... students don't all take the same course at the same time. Do I have to add some kind of subgroup to create the needed slots?

Do I have to specify # of students? If I have 100 students and 100 teachers, and 100 rooms, I could teach 100 courses at the same time, right? So, this error -- not enough slots -- is saying ... I don't have enough what?

Perhaps you need to add subgroups or not. It depends.

If some students of year Sr Kg learn math at same time that other students of year Sr Kg learn arts, you have to put maths and arts at same activity and FET will use only one slot. For this 2 subjects.
In one activity you can put more than one teacher and more than one group, and you can create one subject with name Maths and Arts.

Another way you can create 2 subgroups of Sr Kg. Then you assign some activities to group Sr Kg, and some to Sr Kg1 and others to Sr Kg2.

tevi · July 30, 2010, 01:44:13 PM

Something more...

You have created diferent subjects for diferent years. It's not necessary. You can use subject math for years one to twelve, when you create an activity you match it to students you need.

flossed.org · July 30, 2010, 04:14:15 PM

The schedule worked, but I had decrease values (number of class meetings) for several courses in two different years (same ones: SrKg and Grade 9). Just wondering how "splitting" a class works when grouping. Would that possibly solve the space problem?

After FET output the schedule, I added room numbers (I took them out yesterday), and that created a new problem. Now it's really broken. Don't even know what to ask. But I think the first problem of not being able to "fit" everything is more serious. I'll let you know what I find. Any ideas on whether splitting might help would be appreciated.

Best,

David

flossed.org · July 30, 2010, 05:59:11 PM

I didn't see Tevi's suggestions (2 posts above) until a few minutes ago. I'm finally to the point where I can take them in. I'm trying subgroups. Thank you, everyone. I will report what happens.

flossed.org · July 30, 2010, 08:05:35 PM

I tried subgroups and for grade 9 it worked. For SrKg it didn't yet. But even for 9 there is this new problem: students in the same class are now in different groups -- there is only one English and one Math which they're all supposed to take, but it's in one of the groups.

The choices are:
Physics A 9 or Chemistry A9
Physics B 9 or Chemistry B9
History or Geography
French or Hindi
Art, ICT or Business

When I put all of these into a single class (there aren't that many students -- it's a brand new school), FET tells me (correctly) that there aren't enough hours or slots. That's why I was trying to create more slots and making two subgroups worked -- but it separated the students. Does anyone see a good strategy to use here?

Thank you,

David

tevi · July 30, 2010, 08:33:38 PM

A student choice 5 subjects of the list? One of each row? If yes, don't make subgroups, create 5 subjects like this:
Science A (Physics A 9 or Chemistry A)
Science B (Physics B 9 or Chemistry B9)
Socials (History or Geography)
Lang (French or Hindi)
Misc (Art, ICT or Business)

In each subject put the teachers you need.