[rules-users] Query on loading facts dynamically

[Wolfgang Laun]

For simplicity's sake, I'll assume that a student's exams are numbered
consecutively, and that the number of exams taken is available from a
Student attribute. Then, rules like this one

rule "load last exam"
when
   Student( $id : id, $ex : exams >= 3 )
   not Exam( id == $id, no == $ex )
then
   // code to load and assert last Exam

will create the missing facts.

It seems that you are looking for a "generic" way. There isn't,

-W


2010/7/1 jobin wilson <jobinwilson at gmail.com>
>
> Thanks W for the quick response....you are absolutely correct,to reward all the students based on some criteria,all of them should be in WM.But the average of "last 3 out of all > 75" should become a part of the reward criteria and the challenge as you mentioned would be how to restrict the exam facts to the ones which are relevant for evaluating this criteria.
>
> Is there a concept of some kind of a rule pre-processor or an engine which can identify the context of the rule and load the limited facts based on that context?
>
> Thanks & Regards
> Jobin Wilson
>
>
> 2010/6/30 Wolfgang Laun <wolfgang.laun at gmail.com>
>>
>> If you want to reward all students you'll have to have all students in WM, at one time or other. Assuming that you aren't dealing with all the students in China, it doesn't matter much how you do this.
>>
>> Now as for a student's exams, there might be an advantage if you could restrict the set of facts to those that are actually required to compute the average of "last 3 out of all". But to fetch just these, you'd have to know some key (e.g., student+course) - but I don't see how you can construct that without having the exam object with all its attributes, especially the date.
>>
>> Regards
>> -W
>>
>>
>> 2010/6/30 jobin wilson <jobinwilson at gmail.com>
>>>
>>> Hello List,
>>>
>>> I have a very basic question about inserting facts into the working memory dynamically.For firing the rules,we should be having all our facts in the working memory.In that case,How will we deal with the situation where the facts that we need for evaluation of a particular rule is dependent on the rule itself (needs to be brought it dynamically)?
>>>
>>> Say for example say i want to use rule engine to reward all students with average scores for all subjects > 75 for the past 3 exams.
>>>
>>> The facts that i have are the Student objects & their Subject wise scores(one to many relation;one student to many exams & each exams having many subjects).
>>> I want the "when" condition to be satisfied for all students whose average scores for all subjects for the past 3 exams to be greater than 75
>>> and the consequence to be to just print out the name of the student.
>>>
>>> In this case,should i be loading all the student objects & each of their past exam scores in the whole system to find student objects satisfying this critera?
>>> Since i already know that the rule just need the average scores for just the past 3 exams for each student,wouldn't loading the whole facts be inefficient?
>>> Is there a way in which i can specify somehow how much of the facts needs to be loaded before firing the rule based on the rule itself?
>>> i mean a rule which is aware of the quantity of the facts on which it needs to work on(considering loading 3 facts versus 100 facts)?
>>>
>>> Thanks a lot in advance for all your inputs and suggestions on this.
>>>
>>> Thanks & Regards
>>> Jobin Wilson
>>>
>>>
>>>
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>>>
>>
>>
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