Why does it fail to find a solution?

From: Nicholas Robinson <nprREMOVE@THISbottlehall.co.uk>
Date: Sun Jul 03 2005 - 09:10:22 CEST

Hi Tomaz

Running tablix2 many times gives timetables that always look like the result
below.

If you look at class IIa, it has a timeplace error on Wednesday at lesson 2.
The lessons are CDT (which is a lesson shared with three other classes and
therefore very difficult to move) and English (shared with one other class).
The hole resulting from this error is on Tuesday lesson 9. If you look at the
timetable for class IIb, then it obviously has the same error, but the
corresponding hole is at lesson 6 on Tuesday.

However, it seems a fairly straightforward problem to solve:

1. Move IIa lesson 9 to lesson 6 - this is possible because teacher NPR is
free at this time also.
2. This creates a hole on Tuesday lesson 9 for both class IIa and IIb, so the
shared English lesson can go there.
3. The fitness number is reduced by 50 for the timeplace and increase by 10
for the sameday, so it should be a more attractive solution.

Yet even after many hours and many runs, tablix2 doesn't solve this - and it
often ends up with the same timetable.

Best Wishes

Nick

Received on Sun Jul 03 09:06:18 2005

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