Author Topic: strange file!  (Read 282 times)

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Benahmed Abdelkrim

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strange file!
« on: June 12, 2017, 03:14:30 AM »
Hi
I attached below a file, may be that it will be useful for the improvement of the speed of FET.
We let the time constraints activate " a set of activities occupies max time slots from selection", and FET successfully placed 435 activities out of 442 after a few minutes (nearly 30 minutes), and then endless!
If we disable these constraints (... max time slots from selection) the file is solved in just a few minutes!

If I use "group activities in the initial order of generation" without disabling these constraints (... max time slots from selection), the file is resolved in 1 hour
strange!
B.A/krim

Liviu Lalescu

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Re: strange file!
« Reply #1 on: June 12, 2017, 03:30:07 AM »
Thank you for the report! Volker also uses this trick. I prefer to do nothing inside FET to care about the initial order of the activities in such cases, and let the user decide this.

Let me know if I should add this file to the official Algeria examples.

Benahmed Abdelkrim

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Re: strange file!
« Reply #2 on: June 12, 2017, 03:38:17 AM »
Let me know if I should add this file to the official Algeria examples.

Yes No problem!
B.A/krim

Benahmed Abdelkrim

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Re: strange file!
« Reply #3 on: June 12, 2017, 12:25:09 PM »
Thank you for the report! Volker also uses this trick. I prefer to do nothing inside FET to care about the initial order of the activities in such cases, and let the user decide this.

But why? 
  Hmmm...  pity! It could help improve FET by increasing its speed...
But if you prefer this, surely there is a reason!

B.A/krim

Liviu Lalescu

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Re: strange file!
« Reply #4 on: June 12, 2017, 12:43:28 PM »
Thank you for the report! Volker also uses this trick. I prefer to do nothing inside FET to care about the initial order of the activities in such cases, and let the user decide this.

But why? 
  Hmmm...  pity! It could help improve FET by increasing its speed...
But if you prefer this, surely there is a reason!

I am not sure it will always be a good thing. It is very tricky.

Benahmed Abdelkrim

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Re: strange file!
« Reply #5 on: June 12, 2017, 04:17:42 PM »
Maybe we should rethink "the random number generator"?!
May need to be rewritten?...

B.A/krim

Liviu Lalescu

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Re: strange file!
« Reply #6 on: June 12, 2017, 09:07:36 PM »
Maybe we should rethink "the random number generator"?!
May need to be rewritten?...

No, sorry.
« Last Edit: June 13, 2017, 01:25:59 AM by Liviu Lalescu »

Benahmed Abdelkrim

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Re: strange file!
« Reply #7 on: June 13, 2017, 07:17:13 AM »
Maybe we should rethink "the random number generator"?!
May need to be rewritten?...

No, sorry.

Ok dear Liviu I'm sorry. It was just an idea that came to mind, I did not measure its accuracy, that I wanted to share with you, in order to have more details from you
thank you very much!

yours
« Last Edit: June 13, 2017, 07:45:52 AM by Benahmed Abdelkrim »
B.A/krim

Liviu Lalescu

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Re: strange file!
« Reply #8 on: June 13, 2017, 08:03:25 AM »
Of course, no problem :)

Benahmed Abdelkrim

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Re: strange file!
« Reply #9 on: June 29, 2017, 02:17:15 PM »
Here is the same file with added space constraints. With the time constraint "acttivities occupies max time slots from selection" for the teacher 'M4', FET fails to find a solution.
  But by deactivating this constraint FET  finds the solution successfully, after about 2H.
Then in order to satisfy this constraint quoted above for "M4", I made some changes by hand.
I attach the 2 files before and after changes.
B.A/krim