Suggestion

[abd]

In Algeria, in the morning–afternoon mode:
•   History teachers are not scheduled for activities on Friday, Saturday, and Sunday, so we are obliged to assign them activities on Monday and Thursday.
•   Natural sciences, physics, and technology teachers are not scheduled for activities on Friday, Saturday, Wednesday afternoon, or Wednesday morning and afternoon, so we are obliged to assign them activities on Tuesday and Thursday.
•   Arabic language teachers are not scheduled for activities on Friday, Saturday, Monday afternoon, or Monday morning and afternoon, so we are obliged to assign them activities on Sunday and Tuesday.
•   Mathematics teachers are not scheduled for activities on Thursday, Friday, and Saturday, so we are obliged to assign them activities on Wednesday and Sunday.
•   English and French teachers are not scheduled for activities on Friday, Saturday, and Tuesday, so we are obliged to assign them activities on Monday and Wednesday.
Suggestion:
It would be preferable if you could add in the morning–afternoon mode:
•   A new conditional constraint: If the teacher does not have activities during half-day a, or full day b, or half-days c; d; ... or full days e; f; ..., then he/she must have activities during half-day u, or full day v, or half-days w; x; ... or full days y; z; ....
•   Also another new constraint opposite to the previous one: If the teacher has activities during half-day a, or full day b, or half-days c; d; ... or full days e; f; ..., then he/she must not have activities during half-day u, or full day v, or half-days w; x; ... or full days y; z; ....

[YOUSSEF HOUIET]

يمكن استعمال قيد مجموعتان من الفترات الزمنية المتعارضة لمدرس

[abd]

شكرا جزيلا لك أخي يوسف ؛ ساحاول ؛ كما سابحث عن مقاطع فيديو تشرح ذلك .
وحبدا لو كان رابط يوتوب يوضح ذلك .

[Liviu Lalescu]

I will add your words in the TODO, thank you! It is a research problem. The big problem with FET is the lack of financial support. If the international community would sponsor this, I would try it.