Re: Elegant solution to let OWL/RDF cover Closed World Assumptions (CWA), incl unique Name Assumption (UNA)

It has indeed crossed my mind (and that of some of the people I've been 
talking with) that one may want to have a simple "closure" - i.e., 
something much simpler than what most non-monotonic formalisms provide. 
It seems, though, that some of the things you describe below can be 
achieved by the autoepistemic K operator [1,2], by DL-safe variables 
[3,4], or the approach proposed in [5]. In any case, it needs spelling 
out explicitly...

Best Regards,







On 11/16/2010 12:52 PM, DJA222 wrote:
> Dear OWL Staff,
> Hereby I would like to suggest an elegant solution to let OWL/RDF
> cover Closed World Assumptions (CWA), incl Unique Name Assumption
> (UNA).
> Due to its Open World Assumption (OWA), OWL/RDF  can hardly be used
> for e.g.: 1. finding (:instantiating) pre-defined individuals with a
> certain number of properties or without these properties at all (e.g.
> cardinality 0). 2. validation. OWL/RDF's OWA asserts that everything
> is possible (->infinite) until asserted otherwise by constraints
> (->finite). But doesn't infinity envelopes finity? Isn't processing
> things in a finite world (CWA) just a valid part of the infinite
> world (OWA)? Finite means that things are or (immidiately) can be
> made explicit. Then why not simply introduce a term like
> e.g."Explicit" that can be added to every constraint and applies to
> things/values that are visible at the very moment of instantiation?
> Example class expression: Person and (hasChild exactly 0 Explicit) :
> at the very moment that this class is being instantiated it "scans"
> for (pre-definied) individuals in class Person for which the property
> "hasChild" is explicitly absent (:exactly 0 Explicit). Although
> OWL/RDF itself leaves open the possibility that the individuals still
> might have hidden "hasChild" properties, the reasoner just looks for
> explicitly absent properties because the class expression tells it to
> do so.
> This way it can also be used for validation/integrity-check  with a
> class expression with "Explicit" included: if something is asserted,
> that can't be derived from explicitly present assertions at the very
> moment of instantiation, than this will be reported: NOT as being a
> OWL/RDF error/conflict/inconsistency, but just as a note to the user
> who fabricated this class expression. Again, without OWL/RDF itself
> denying that there might still be assertions that are just not
> visible at the moment of instantiation.
> Same story for UNA: by adding a term like e.g. "Unique" in a class
> expression it might notify the user (who wrote the expression) upon
> instantiation, that it has found individuals who are asserted
> (directly or implied) to be identical but have different names or
> that it has found more individuals than expected. Again, without
> OWL/RDF itself denying that there might by assertions that are just
> not visible at the moment of instantiation.
> All above OWL/RDF examples would still comply with OWA and Non-UNA
> demands, by assuming the possible outcome (with the terms "Explicit"
> and "Unique" used in expressions) not as OWL/RDF conlicts, but just
> as (user) notifications.
> Above is extremely important in research where INDIVIDUALS and
> relations between them are at the focus, instead of the more generic
> class approach. In certain researches,  thousands and thousands of
> data snippets (:Individuals) come in from different places and you
> want to look for certain properties/relations that these pieces
> share/have with/to one another. This can not easily be automated with
> present OWL/RDF. Yes, one might use SPARQL in some ways, but the aim
> is to let simple class instantiation do its work.
> In my conviction, with a slight addition, OWL/RDF semantics can proof
> to be a more complete basis for ANY semantic real world application
> and solution, and not just for a limited part!
> Hopefully you might reconsider this idea, or find find some similar
> solution, that really is in the need of many (potential) OWL/RDF
> practitioners.
> Sincerely yours,
> DJ Alexander

Prof. Dr. Pascal Hitzler
Dept. of Computer Science, Wright State University, Dayton, OH
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Received on Thursday, 18 November 2010 19:02:29 UTC