Re: [RIF] Reaction to the proposal by Boley, Kifer et al

"Peter F. Patel-Schneider" <pfps@inf.unibz.it> wrote:
> 
> I, on the other hand, have some serious concerns with the proposal.  
> 
> I worry about using a substitution in the basis of the semantics of
> conditions, in particular because the rest of the semantics of conditionals
> (including the semantics of existentials) are unspecified in the proposal.
> Will this actually end up close to a known logic?

This is based on a known logic: infinite Herbrand interpretations.

It is easy to extend this semantics for general, non-Herbrand domains.
But this will be useful only for the FOL dialect. The others will have to
fall back on Herbrand interpretations.


> I also worry about the expressivity of conditions.  They already have
> functions and existentials, and two kinds of negation.

These features would need to be associated with the nodes of the
syntactic/semantic taxonomy (which we mentioned in the intro). There will
be nodes in this taxonomy, which will not include function symbols. Also,
FOL will obviously be located in the area that doesn't include default negation.

> We have also just seen a proposal to add counted quantifiers.

This was thrown in but to make it fly one would have to incorporate these
quantifiers into the answer-set and well-founded semantics. (My understanding
is that Francois main interest is in CWA-based dialects.)
I think a better and a more natural way to express this kind of features is to
use aggregate functions. (For CWA-based dialects.)


> I worry about the connection between the proposal and RDF and OWL.  I do
> not view it as appropriate to relegate existing Semantic Web languages to
> an add-on query interface.

Why?

A query interface is a very general thing. It can range from seamless
integration (e.g., in FOL-based dialects) to Rosati and Eiter et al. style
integration, to external calls to ontologies. Different degrees of
integration will be appropriate for different dialects. (For instance, what
would be the appropriate integration for PR rules?)


	--michael  


> Peter F. Patel-Schneider
> 
> 
>

Received on Wednesday, 3 May 2006 05:35:29 UTC