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FET Support (English) => Get Help => Topic started by: pg788 on July 02, 2018, 02:25:06 PM

Title: What's the use of max span for teacher when we have max gaps per day/week?
Post by: pg788 on July 02, 2018, 02:25:06 PM
What's the use of max span for a teacher when we have max gaps per day/week already?
Title: Re: What's the use of max span for teacher when we have max gaps per day/week?
Post by: Liviu Lalescu on July 02, 2018, 03:47:34 PM
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.
Title: Re: What's the use of max span for teacher when we have max gaps per day/week?
Post by: pg788 on July 02, 2018, 05:10:58 PM
Won't a combination of max hrs +max gaps per day do the work of max span per day?
Title: Re: What's the use of max span for teacher when we have max gaps per day/week?
Post by: Liviu Lalescu on July 02, 2018, 05:30:11 PM
Quote from: pg788 on July 02, 2018, 05:10:58 PM
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.
Title: Re: What's the use of max span for teacher when we have max gaps per day/week?
Post by: Volker Dirr on July 02, 2018, 05:31:35 PM
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%
Title: Re: What's the use of max span for teacher when we have max gaps per day/week?
Post by: pg788 on July 03, 2018, 06:23:40 AM
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!