How to prevent two selected buildings from being used next to each other?

[aofpm]

How to prevent two selected buildings from being used next to each other?

[Liviu Lalescu]

Do you mean B1 and B2, they should not appear consecutively on the same day in students' set S / teacher's T timetable? If you can use min gaps between buildings constraints, it is easy, otherwise, if you mean only these two exact buildings, you might need a customization.

[aofpm]

I mean, students should not study Building 3 and Building 4 consecutively.thank you

[Liviu Lalescu]

You are welcome!

If you have only Building 3 and Building 4 in your data, or you can reduce all your buildings to these two buildings (like ignoring Building 1, 2, 5, 6, ...), you can use the official FET with a constraint students min 1 gap between building changes.

Otherwise (if in your timetable you need to consider all the buildings, for other buildings constraints), you need a customization.

Or, another possibility to avoid the customization would be to add a tag AT3 to all the activities in Building 3 and a tag AT4 to all the activities in Building 4, if this is possible (if you know the building of each activity before generating), and use 2 constraints students min gaps between ordered pair of activity tags, one between (AT3, AT4) and the other between (AT4, AT3).