Re: [rules-users] drools queries: strange dependency
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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