[OWL Compatibility] Re: RIF & OWL compatibility

[I moved this discussion to the RIF list, where is belongs]

On Mon, 2006-01-02 at 01:22 +0100, Enrico Franconi wrote:
> In the document <http://www.w3.org/2005/rules/wg/wiki/ 
> OWL_Compatibility>, please add a reference to the use case "Managing  
> incomplete information" <http://www.w3.org/2005/rules/wg/wiki/ 
> Managing_incomplete_information>. Thi use case was exactly meant to  
> help understanding the problems in compatibility of rules with OWL/RDF.
> 
> In particular:
> 
> - at the end of section "Herbrand universe and OWL", please refer to  
> the example "9.1. (Rules involving existential information)"
> 
> - at the end of section "Disjunction in OWL", please refer to the  
> examples "9.2. (Rules involving disjunctive information)" and "9.3.  
> (Rules involving multiple model information)"

I think this is exactly where the wiki helps: Several people
contributing to the same document.

> 
> Moreover, it seems to me that the section "Negation in OWL" is a bit  
> misleading. In fact, even in the rules world there is a distinction  
> between classical negation, negation-as-failure, and intuitionistic  
> negation. Clearly, OWL negation corresponds to classical negation in  
> the rule system; so, I don't see much of a quarrel here.

Agreed.

> 
> Finally, the section "Approaches to Compatibility" neglects most of  
> the literature available, and its current goal is rather obscure.  

It's current goal is to have a first go at describing different
approaches for achieving compatibility. Everyone is invited to add more
approaches.

> What is a "superset approach"? Is it really true that "There are  
> several nonmonotonic logics which are candidates for such a  
> formalism, such as circumscription, autoepistemic logic and default  
> logic"? Can you encode DL's in such logics? Well, yes - if you really  
> mean a superset of FOL with non-mon operators; but does it really  
> make sense to say that? In the "black box approach", as you mean it,  

Yes, a superset of FOL was meant here. This approach probably doesn't
make sense in a practical setting, but it is a possible approach.

> it is *not* true that "OWL DL and the LP rules are viewed as black  
> boxes which exchange only ground facts". Please, first study Rosati's  
> and Eiter's works before stating these things. Moreover, the  
> statement: "Second, the existential consequences cannot be reused,  
> since it is not possible to deal with existential information in LP  
> rules", is false.

I actually defined the black box approach there, and I defined that the
OWL DL ontology and the LP rule base are viewed as black boxes which
exchange ground fact. Perhaps this approach needs to be refined, but I'm
not sure.
I'm not yet aware of Rosati's approach, but his paper is on my stack.
As far as I understood Eiter et al's approach, it works exactly as
described here. One can include queries to a DL ontology in the body of
LP rules; it is also possible to specify which facts needs to be added
to the DL ontology before executing the query. 

Wrt. the existential information: the semantics of LP rules is based on
Herbrand models, which means (among other things) that every individual
in the universe is represented with a name in the language. This makes
it impossible to truly capture existential information.


Best, Jos

> 
> cheers
> --e.
> 
--
Jos de Bruijn,        http://www.debruijn.net/
+43 512 507 6475         jos.debruijn@deri.org

DERI                      http://www.deri.org/
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