Re: [rules-users] Egg Planning: number of facts is also a planning variable
Op 16-10-12 00:30, Paul Adams schreef:
Hi everyone,
I'm new to Drools, so apologies if I'm missing something obvious or mixing up my
terms here. Hopefully the subject line got someone's attention!
My problem is this (somewhat contrived and simplified):
Facts:
1. A person would like to eat 3 eggs per day, of each of several different breeds
(Legbar, Rhode Island Red, Dorking)
2. A hen takes 45 days to get to egg-laying stage (varies by breed)
3. At maturity, each hen lays 2 eggs every 10 days (also varies by breed)
4. A hen house has 30 available roosts
5. Each hen can lay 5 times before they give up (luckily for us this isn't really
true!)
lol! I wonder what you're really planning ;)
I would expect that:
@PlanningEntity HenAssignment {
Hen hen; // a Hen has a Breed
@PlanningVariable Roost roost;
@PlanningVariable Day startingDay;
}
I am not sure if your number of Hens is static or dynamic.
<note>
If it's dynamic you might want to consider this alternative:
@PlanningEntity EggDonation {
Day day;
@PlanningVariable Hen hen;
@PlanningVariable Roost roost;
}
Which might be better of split up 2 entity classes (but until the placer
API is released, construction heuristics don't support that well)
</note>
My planning problem is to figure out how many chicks I need to buy, when I need to buy
them, and to allocate them to a particular roost for their entire egg-laying life.
Basically what I would like the solution to contain is an allocation of a particular hen
to a roost for a particular period, when the eggs will appear, and when a roost will
become free to plan more hens.
Hard Constraint:
No hen can share the same roost
The problem feels like the hospital bed problem in the examples, but where the number of
patients is both a planning variable and a fact, and the planning period is undefined. As
I said, the problem is paraphrased and simplified - there are a number of soft constraints
- some hens like it hot :-)
It's basically hospital bed planning but without a
plannable admission
date, but with no need that a patient can switch beds ever.
Take a look at this post:
https://plus.google.com/112811208792575157490/posts/82h37pBvQ5m
I would appreciate any guidance as to how I might model this problem, or any
simplifications I could make.
Many thanks,
Paul.
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