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

In similar spirit, axioms with CWA and UNA can be seen as special cases of
integrity constraints. A semantics is proposed in [1]. DJ's proposal gave it
a syntax.



On Thu, Nov 18, 2010 at 14:01, Pascal Hitzler <>wrote:

> 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,
> Pascal.
> [1]
> [2]
> [3]
> [4]
> [5]
> 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
> Semantic Web Textbook:
> Semantic Web Journal:

Received on Friday, 19 November 2010 14:17:36 UTC