What's the use of max span for teacher when we have max gaps per day/week?

[pg788]

What's the use of max span for a teacher when we have max gaps per day/week already?

[Liviu Lalescu]

Max span per week would be indeed useless. But max span per day is useful. It is the length of the real working day for a teacher.

[pg788]

Won't a combination of max hrs +max gaps per day do the work of max span per day?

[Liviu Lalescu]

Won't a combination of max hrs +max gaps per day do the work of max span per day?

No. Consider:

- max hours daily 4;
- max gaps daily 4;

versus

- max span daily 8.

With max span it accepts also 6 hours + 2 gaps, and 2 hours + 6 gaps.

[Volker Dirr]

No. You can't sum constraints so easy.

Just an easier example:
constraint max hours per day = 2 with 100%
+
constraint max hours per day = 3 with 100%

doesn't mean
constraint max hours per day = 5 with 100%

It mean in fact only
constraint max hours per day = 2 with 100%

[pg788]

Oh no, I wasn't suggesting to sum up constraints. The "+" was used as a logical AND. But Liviu's example makes it clear. Thanks!