W3C home > Mailing lists > Public > public-owl-comments@w3.org > November 2010

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

From: DJA222 <dja222@hotmail.com>
Date: Tue, 16 Nov 2010 18:52:45 +0100
Message-ID: <COL116-DS1686AB5A419B88BD35663C92370@phx.gbl>
To: <public-owl-comments@w3.org>
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
Received on Thursday, 18 November 2010 10:56:56 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 18 November 2010 10:56:56 GMT