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Topics - liquid

General Stuff / Chained constraints
August 16, 2018, 11:24:21 AM
Life brings a lot of experience, more than a developer may predict. In my timetable, I needed something like "three activities are consecutive". Assuming "consecutiveness" relation is transient, if you declare that activity_1 and activity_2 are consecutive and activity_2 and activity_3 are too consecutive there should be relation that activity_1, activity_2 and activity_3 are consecutive. Additionally, activity_3 must end students day. In theory, but program gets stuck after a small percent of placed activities.
My workaround was this: activity_1 and activity_2 are consecutive, activity_3 must end students day and that three activities were grouped. The program then solves the timetable but it needs more time to do it.
The question is: is the program aware of chained activities and can warn a user that they may lead to no solution?
After running program from terminal there appears this message.
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
I don't know what is its importance but it's for your knowledge.
General Stuff / Multiple timetable generation
August 14, 2018, 01:41:01 PM
After generation of several timetables, which one can I view within FET program and how can I switch between them? I don't mean HTML version that are in separate folders.
I have a data plan for 852 activities. It's not an easy one. I try to figure out how FET tries to place activities which might help to make a better data file. What I see is that after 3 mins, FET managed to place 669 activities and then it continuously decreased number of placed ones. After 11 hrs FET says it placed 302 activities and it's been stuck at this point for 3 or more hours. With 300 of 850 activities placed FET has a plenty of time slots and space to try placing but it does not do it, I suppose, or it's not visible. Is there something in the algorithm that prevents FET from more intensive searching?
Report a Bug / assertion failed
July 18, 2018, 08:34:53 PM
For the first time, I met the following assertion failure. It does not mean anything for me. What about you?

fet: interface/timetableviewstudentstimehorizontalform.cpp:540: void TimetableViewStudentsTimeHorizontalForm::updateStudentsTimetableTable(): Assertion `d*gt.rules.nHoursPerDay+h<studentsTimetableTable->columnCount()' failed.

It happened while closing the dialog after finished successful generation.
General Stuff / max placed activities
July 17, 2018, 02:40:41 PM
Given the status of max placed activities I wonder if the next time FET reaches that number it replaces the previous schedule. I think that would be useful after writing the highest timetable to check e.g. conflicts.
Get Help / teacher home room
July 13, 2018, 12:38:38 PM
How to increase probability that a teacher will have an activity in his home room rather than in other allowed by space constraint for a subject? I've assigned a home room for a teacher with the weight of 100% and an activity has been scheduled in other room despite there was a free time slot in the teacher home room.
I suggest (please) to divide days with bolder or thicker lines. For me, it would enhance clarity when viewing or printing a schedule, both in printable and viewable versions.
Get Help / Up/Down Constraints
June 07, 2018, 11:03:18 PM
What does exactly mean moving constraints up and down? Does it make difference in treating them by program?
I set room constraints in two ways:

  • for younger students - a group has set of home rooms
  • for older students - subject has preferred set of rooms
The problem arose when both younger and older students have the same subject. If I specify subject preferred set of rooms with weight 100% the timetable cannot be generated with this message:
QuoteCannot generate timetable, because for activity with id==nn you have no allowed preferred room (from preferred room(s) constraints).
If the weight is say 95% timetable can be generated but there is a lot of soft conflicts.

We have the similar case when it would be desirable to set for a subject e.g. two rooms out of ten with weight 100% and the rest eight with a little less weight (e.g. 95%) which would mean that it's preferable a subject should be in one of these two rooms and acceptable in other ones. When I set these two constraints we have again a lot of soft conflicts. Moreover, the statistics say that
QuoteYou have nn activities which might end up in an unspecified room
I think I'll have to set preferred rooms for activities unless there is another solution. The number of activities is much bigger than rooms and groups.
Get Help / Subject not allowed in certain room(s)
May 03, 2018, 06:31:35 AM
I understand the purpose of constraint "A subject has preferred room / set of preferred rooms". Sometimes it would be convenient to set a subject is disallowed in a room or a set of. Is it possible?
Get Help / efectively assign students to given room
November 02, 2014, 05:53:52 AM
I'd like a group of students to have most of its activities in a given room (max 2). I tried to assign a preferred room for activities, setting a room as home room for this group, but timetables are not satisfactory. I mean this group is allocated to other rooms too. What should I do?
Get Help / help on error - preferred rooms constraint
November 01, 2014, 10:47:33 PM
I'd ask for explanation of this error which I don't understand:

Cannot generate timetable, because for activity with id==312 you have no allowed preferred room (from preferred room(s) constraints).
Generally, constraints have the two forms:
item has preferred other item
item has preferred set of other items

I experience that during data preparation for a timetable the things are often changing or are caused by planning progress in the way it's necessary to add to a constraint of first form some other item, making the constraint of the second form. In this case, I must delete the former constraint and create a new one, to respect a set of other items. It would be simpler to just add other item to previously set up one, making therefore a set of preferred other items automatically. I'm not sure if the set of preferred other items is equivalent to many constraints of the first form (with one other item). If it were I think it would be possible to abandon this distinction in a future "big" update of FET program.
I wonder whether the reason for this rather technical (a matter of development) and difficult to change or may be not so difficult.
General Stuff / translation of timetable
October 25, 2014, 01:47:52 PM
What's the best way to translate only the timetable generated by FET? For me, it's not a problem to use FET in English but it would be convenient to have generated timetable translated into other language.
We've got a constraint which tries to place an activity (or set of ones) at the end of students' day. How to place an activity at the beginning of the day?
General Stuff / add activity - about consecutive
October 19, 2014, 05:59:11 AM
If I set split activity to have min. days to 1 and weight to 100% is setting "consecutive" significant?
Get Help / two activities in the same room
October 17, 2014, 10:38:31 PM
I know it may be contrary to what FET does but sometimes two activities may or should be in the same "room", e.g. swimming pool. How to do this? I mean two classes (groups) are allowed to but needn't be assigned to one room while having swimming lessons, provided swimming pool is big enough to fit more than one group.
At the primary school, there are students of age from 6 to 14. How to prevent allocating activities for older students to room where desks and chairs are too small for them? I don't think the set of home rooms is the most suitable solution for that issue. Indeed, I assigned some home rooms for classes 1-3 and it works. Is this the only solution?
Suggestions / alias for year/group/subgroup
October 12, 2014, 05:09:38 AM
I think it would be useful to introduce aliases for years, groups and subgroups. Their names sound kind of technical, particularly when one lets FET automatic year divide. It's OK when you work with schedule but it would be more readable when aliases were shown (of course if present) on the timetable.