[rules-users] fact tuples selection - what are the principles - a bit confused?

[Olenin, Vladimir (MOH)]

No, I'm not concerned with the order in this particular case - just trying
to figure out what I should be taking into account or rely on when doing the
design. Thanks for taking the time to go through (now that I scrolled
through it myself :-) ) this quite lengthy email.

 

Vlad

 

  _____  

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Michael Neale
Sent: 12 February 2007 23:53
To: Rules Users List
Subject: Re: [rules-users] fact tuples selection - what are the principles -
a bit confused?

 

that sounds correct.

No you can't really depend on things happening in a certain order. of course
it will be consistent between executions for the same data, but you can't
count on that. It would mostly be effected by the order in which you assert
facts. 

I guess the question is why are you concerned in what order it does things?

Michael

On 2/13/07, Olenin, Vladimir (MOH) < <mailto:Vladimir.Olenin at moh.gov.on.ca>
Vladimir.Olenin at moh.gov.on.ca> wrote:

Hi,

I was trying to find more detailed explanation on how the fact tuples for 
activations are being selected based on the constraints, but couldn't find
much. So, I guess I just want to assert my understanding of this process is
correct.

Assuming I have the following set of 'Accounts' with the fields: 

ID  | Province       | City        | Type        | Balance
----------------------------------------------------------------
1  | ON             | Toronto     | Checking    | 1000
2  | BC             | Vancouver   | Checking    | 100 
3  | ON             | Toronto     | Visa        | 2000
4  | ON             | Toronto     | Checking    |-100
5  | BC             | Vancouver   | Checking    | 100
6  | BC             | Vancouver   | Visa        | 150 
7  | AB             | Calgary     | Checking    | 100
7  | AB             | Toronto     | Checking    | 300

I have two rules to process:

1) within each province, the sum of balances on Visa accounts should less 
then 10 times the sum of balances on Checking accounts (within the same
province)
2) within each province, the sum of balances on Checking accounts should be
a positive number
3) within each province and within each city, the number of visa accounts 
should be no more than 2 times the number of checking accounts

If I model my business objects like this:

1) Account  (id, province, city, type, balance)
2) Province (province)
3) City     (province, city) 


And WorkingMemory will be initialized (for the data above) with:
        - 7 Account instances (ids 1 through 7)
        - 3 Province instances (ON, AB, BC)
        - 3 City instances (Toronto, Vancouver, Calgary) 


Then the rules containing 'within province' would read like:
-----------------
Rule '1'
When
        Province($prov: province)
        $a: Account(province == $prov)
Then
        // accumulate sums on Checking and Visa accounts as Edson showed in 
previous emails
End
-----------------


The rule containing 'within province, within city' would have then:
-------------
Rule '3'
When
        Province($prov: province)
      City($city: city, province = $prov) 
        $a: Account(province = $prov, city = $city)
Then
        // accumulate sums on Checking and Visa accounts as Edson showed in
previous emails
-------------


Is this correct business object model to achieve the goal? Do I understand 
correctly that the LHS statement:


        Province($prov: province)
      City($city: city, province = $prov)
        $a: Account(province = $prov, city = $city)


Can be read as:

        For each province 
                For each city within the province
                        For each account for the given city and province



What 'guides' the order in which fact tuples are selected from the set of 
all facts in the WorkingMemory? Can any particular sequence be guaranteed?

Thanks!

Vlad
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