The best way to win principals is to show them that a ridiculously complex constrain may be applied and calculated automatically.

• 4.5 school hours of S per week (4 hours on odd weeks and 5 hours on even weeks)
• when there is the fifth hour in the week, then this hour may be the second hour of the subject S on that day
• if it is on the same day, it should be immediately after the previous hour of the subject S
• in the above case, it must be the last hour for the teacher
• three classes of students are divided into 5 groups for the subject S
• there are 4 teachers for those 5 groups, one teacher teaches groups number 2 and 4
• there is a given list of students for groups 1, 3 and 5 and a combined list for students for groups 2 and 4
• computer should divide the combined list into two separated lists (2 and 4) but they must not differ for more than 4 students in size
• as one of those groups (2 or 4) are always idle, the subject M which is equally divided, must be taught then - or the S should be the first hour of the day
• for there are only 4 hours of subject M per week
• there are only 3 teachers of M
• there are also 3 hours of subject A per week for those same students in 5 differently set groups
• there are 5 teachers of A, but one of them also teaches the group number 1 of S
• it would be nice but not mandatory if the number of waiting hours for students were 0

This is a real life example, I have discussed 1 hour ago with one of the teachers (math teacher) in one of our schools. It is not the most complex demand we had, by far.

S = Slovenian language M = Math A = Anglescina (guess what that is)