[rules-users] drools queries: strange dependency

[Upali Kohomban]

hi Davide,

Your summary is quite accurate about my case.

Thanks for the pointer, I will look in to hybrid chaining once I do a 
little investigation on why exactly the original problem occurred. I'm 
still having little issues with the 5.5.1 source compilation (for which 
your help worked flawlessly to get the source working, but there were 
test fails during the compilation. I will try myself to fix them before 
asking questions on that).

As i said, the bigger problem is with the rules that are transitive in 
nature. Let's say there is a is_in rule which is used to derive spacial 
relationships. For instance, a concrete example

is_in (uni_of_michigan, ann_arbor).
is_in(ann_arbor, MI).
is_in(MI, USA).
is_in(A, C) <- is_in(A, B), is_in(B, C).

I want to deduce (in general course of reasoning) such stuff as 
is_in(uni_of_michigan, USA), but if I do it in the regular drools way, 
I'd end up with a load of unnecessary deductions. This is the biggest 
problem I have. If you want a more involved concrete example, say I 
define (for the sake of simplicity)

romantic(A) <- scenic(A), secluded(A).
scenic(A) <- next_to(A, B), scenic_artefact(B).
scenic_artefact(B) <- lake(B) or waterfall(B) or ... and so on
secluded(A) <-  [ situated further than N km from the nearest city ]

Now this last rule is where logic gives way to POJO and databases. It 
seems to me that this is the most sensible thing to do. Also, this is as 
far as I want to go at the moment. (Having known the non-boolean 
reasoning ability of drools from your mail, I can think of many ways I 
want to use it :) )

I looked into your profile and saw that you have a background on the 
ontologies. Especially what you have mentioned under Drools - "Open 
Source Knowledge Integration and Reasoning Platform" in your university 
profile seems quite intersting and seems to be exactly the things I 
might be needing in the near future. I was thinking that I'll have to 
implement non-boolean reasoning using some fuzzy toolkit, if it becomes 
available with drools I'll be really happy to give it a try.

If you have any material to share for further reading on your drools 
research, I'd be grateful.

Thanks,
Upali


On 15/04/2013 03:10, Davide Sottara wrote:
> Correct me if I'm wrong, I would summarize your requirements as follows:
> - you need some "A-box" reasoning, but you are fine with a rule-based 
> approach
> - the object-oriented integration Drools provides is quite convenient
> - you have large data sets for which an opportunistic, 
> "query-oriented" approach
> would work better rather than a fully generative "forward chaining" 
> approach
>
> Drools "hybrid-chaining" approach could be very useful here - I'm not 
> sure how
> well documented it is, and how you are planning to use it, but it 
> would be interesting
> to see one of your rules - even "stripped" of the details you don't 
> want to show -
> to discuss the behaviour of the engine and its implications.
>
> I had a use case apparently very similar to yours some time ago.. I'm 
> working even
> now on some experimental forms of rule/object/ontology integration. 
> The "trait"
> feature might be an alternative to the explicit addition of classes to 
> objects .. it was
> enhanced a few days ago to support updates and modifications.
> If you have an ontology to begin with, you might also be interested in 
> the ontology -> class
> conversion tool I'm working on even now
>
> Davide


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