[rules-users] [planner] Questions about employee shift rostering example
Geoffrey De Smet
ge0ffrey.spam at gmail.com
Fri Jan 15 05:20:50 EST 2010
[CC'd to the user list]
Hi Samuel,
> Happy new year and all the best for you and your family.
Happy new year too :)
> As you can see below, I tried posting a message on the mailing list but
> unfortunately I am not authorized.
If that doesn't work out (it should!), try the nabble.com forum or the
gmane.org newsgroup:
http://n3.nabble.com/Drools-User-f47000.html
I use gmane.org myself from Thunderbird.
> Geoffrey, I saw a paper on the trunk of drools planner where you address
> the issue about employee shift rostering.
> There is no source, I don't know what level of thinking you're in, but I
> have two questions:
>
I haven't made an example of employee shift rostering (or bin packaging
or vehicle routing) yet.
Employee shift rostering is closely related too curriculum course
scheduling,
so I advice to get to know the curriculum course example inside and out :)
Drools (Planner) is kinda like JPA:
you can model your domain pretty much how you like,
but how you model your domain can impact the complexity of your rules (~
JPA-QL's).
Don't make your domain too smart to help your first rules,
because it will strangle rules (and even moves) you implement later.
Keep your domain on low level details.
> "Each shift has for each specialism a minimal staff size"
> how do you manage the team size ?
> Is there a list of people in the Shift object ? Or an accumulate function
> in the rule ?
>
I'd say: experiment with both and let me know which works best :)
Until now, I 've always gone for the "accumulate function in a rule" manner.
I strongly believe in keeping the domain diagram very simple:
http://beta.parleys.com/#id=1714&st=5&sl=14
So only one "red class".
Only one class that the moves change, only one class that you need to
tell the working memory that has changed.
I believe (and I think I 've seen) that this improves delta based score
calculation.
The problem is that some rules, require to check the sum of thing and
you need an accumulate,
like this rule in examinationScoreRules.drl:
rule "roomCapacityTooSmall" // TODO improve performance, as it takes 50%
of the performance
when
$period : Period();
$room : Room($capacity : capacity);
$totalStudentSize : Number(intValue > $capacity) from accumulate(
Exam(period == $period, room == $room, $studentSize :
topicStudentSize),
sum($studentSize) // Vote for
http://jira.jboss.com/jira/browse/JBRULES-1075
);
...
And Drools 5.0's forward chaining becomes backward chaining once you do
this.
Forward chaining = delta based score calculation.
Backward chaining = NO delta based score calculation.
The answer is "true modify", which mark is working on, but probably
won't make 5.1 I fear.
http://blog.athico.com/2010/01/rete-and-true-modify.html
https://jira.jboss.org/jira/browse/JBRULES-2240
Despite that, I still go for "accumulate function in a rule" each time
and take the performance hit.
Meanwhile I poke Mark :)
Remember: StartingSolutionInitializer and
relativeSelection/absoluteSelection bring far greater peformance rewards.
The "a list of people in the Shift object" approach might be better
untill "true modify"'s been solved,
but I believe it hurts your design in the long run.
But do experiment with both approaches, I 'd love to get some feed-back
on this.
> "minimal 35 hours rest each week"
> How do you check that constraint ? Is there a week object that you parse to
> check that there are 2 consecutive days each week? Or is that the generated
> movements already meet this hard constraint ?
>
How do you define a week? From monday to monday or any 7 days in a row?
In either case, just search for a pattern where that does _not_ happen.
It does depend on how you modeled your domain, I 'd have to see the code
in detail.
Take a look at this rule:
// CurriculumCompactness: Lectures belonging to a curriculum should be
adjacent
// to each other (i.e., in consecutive periods).
// For a given curriculum we account for a violation every time there is
one lecture not adjacent
// to any other lecture within the same day.
// Each isolated lecture in a curriculum counts as 2 points of penalty.
rule "curriculumCompactness"
when
$curriculum : Curriculum();
$lecture : Lecture(curriculumList contains $curriculum,
$day : day, $timeslotIndex : timeslotIndex
);
not Lecture(curriculumList contains $curriculum,
day == $day, timeslotIndex == ($timeslotIndex - 1)
);
not Lecture(curriculumList contains $curriculum,
day == $day, timeslotIndex == ($timeslotIndex + 1)
);
then
insertLogical(new
IntConstraintOccurrence("curriculumCompactness",
ConstraintType.NEGATIVE_SOFT,
2,
$lecture, $curriculum));
end
PS: next week I 'll be presenting Drools Planner in a Lille JUG.
With kind regards,
Geoffrey De Smet
Samuel Deballon schreef:
> Hello Geoffrey,
>
> Happy new year and all the best for you and your family.
>
> As you can see below, I tried posting a message on the mailing list but
> unfortunately I am not authorized.
>
> I sent an email to the administrator, but until you can answer questions in
> the email below.
>
> Note : I'll post the discussion once I have access.
> Do not worry I understand if you do not respond (I have not forgotten the
> remarks in your previous mail)
>
> If my questions aren't specific enough, let me know.
>
> In any case, thank you in advance for your response..
>
> With kind regards,
>
> Samuel Deballon
>
> CSC • This is a PRIVATE message. If you are not the intended recipient,
> please delete without copying and kindly advise us by e-mail of the mistake
> in delivery. NOTE: Regardless of content, this e-mail shall not operate to
> bind CSC to any order or other contract unless pursuant to explicit written
> agreement or government initiative expressly permitting the use of e-mail
> for such purpose • CSC Computer Sciences SAS • Registered Office: Immeuble
> Le Balzac, 10 Place des Vosges, 92072 Paris La Défense Cedex, France •
> Registered in France: RCS Nanterre B 315 268 664
> ----- Forwarded by Samuel Deballon/FRA/CSC on 14/01/2010 16:30 -----
> |------------>
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> |rules-users-owner at lists.jboss.org |
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> |------------>
> | To: |
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> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> |Samuel Deballon/FRA/CSC at CSC |
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
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> | Date: |
> |------------>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> |14/01/2010 10:24 |
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> |------------>
> | Subject: |
> |------------>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> |[Drools-planner] : Questions about employee shift rostering example |
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
>
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>
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>
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> ----- Message from Samuel Deballon <sdeballon at csc.com> on Thu, 14 Jan 2010
> 10:26:06 +0100 -----
>
> To: rules-users at lists.jboss.org
>
> Subject: [Drools-planner] : Questions about employee shift
> rostering example
>
>
>
> Hi all, Hi Geoffrey,
>
> Geoffrey, I saw a paper on the trunk of drools planner where you address
> the issue about employee shift rostering.
> There is no source, I don't know what level of thinking you're in, but I
> have two questions:
>
> "Each shift has for each specialism a minimal staff size"
> how do you manage the team size ?
> Is there a list of people in the Shift object ? Or an accumulate function
> in the rule ?
>
> "minimal 35 hours rest each week"
> How do you check that constraint ? Is there a week object that you parse to
> check that there are 2 consecutive days each week? Or is that the generated
> movements already meet this hard constraint ?
>
> Thanks in advance for your answer,
>
> Samuel
>
>
> CSC • This is a PRIVATE message. If you are not the intended recipient,
> please delete without copying and kindly advise us by e-mail of the mistake
> in delivery. NOTE: Regardless of content, this e-mail shall not operate to
> bind CSC to any order or other contract unless pursuant to explicit written
> agreement or government initiative expressly permitting the use of e-mail
> for such purpose • CSC Computer Sciences SAS • Registered Office: Immeuble
> Le Balzac, 10 Place des Vosges, 92072 Paris La Défense Cedex, France •
> Registered in France: RCS Nanterre B 315 268 664
>
>
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