Re: fulfilment of my action of today

Exactly. If we use rdfs:subclassOf then it will be useless for the most
part. It is hard to come by with languages that use the semantics of
rdfs:subclassOf.


	--michael  


Chris Welty <cawelty@gmail.com> wrote:
> 
> Michael Kifer wrote:
> > Rumblings on why we need classification terms in RIF
> > (and why RDF's vocab should not be used)
> > ===================================================
> > 
> > Two issues: whether we should define facilities for expressing some data
> > model stuff and whether we should use rdfs for this.
> > 
> > Rationale:
> >    If we do not have such constructs then everybody will be inventing their
> >    own. People will not be able to specify any part of their data model in RIF
> >    which will reduce the usefulness of RIF as an exchange language.
> > 
> > Why it is not good to use RDF's facilities to define class hierarchies.:
> >    RDF is a foreign language whose semantics is burdened with non-standard
> >    things. For instance, subclass is reflexive.
> > 
> >    This is bad because not every language out there uses reflexive subclasses.
> >    For instance, if we map, say, FLORA-2's subclass relationship to RDFS's then
> >    in the translation (RIF) the query whether foo is a subclass of foo will
> >    say "yes" but in FLORA-2 it will say "no".
> 
> </chair>
> No, no - translating flora2:subclass into rdfs:subclass would be 
> incorrect, because they have different semantics.  For me, this is the 
> stronger point in favor of rif:subclass - since so few systems use the 
> rdfs semantics for subclass, very few systems when translating into 
> RIF would use it in their translations.
> 
> Same for below.  You shouldn't translate ilog:subclass into 
> rdfs:subclass.  So, in fact, as far as we know, only rdfs based 
> systems would ever use rdfs:subclass when translating through rif, and 
> everyone else would have to invent their own.
> <chair>
> 
> > 
> >    Let's look at some other examples, like ILOG. From my limited experience
> >    with it, I remember that it uses Java as its data model. So, suppose
> >    there is a class foo in ILOG, which comes from Java. An ILOG set of
> >    rules must not derive "foo sub foo" because this is not true in the data
> >    model. However, it we translate Java subclass relationship into
> >    rdfs:subclassOf then the resulting RIF translation should generate "foo
> >    sub foo". (In truth, as I recall, ILOG does not have "sub" in the heads
> >    of the rules, but it is easy to imagine that next year ILOG is extended
> >    with something like a query facility. Then their stock will plummet
> >    because their rule sets will not be faithfully exchangeable through RIF
> >    :-)
> 
> 
> 
> -- 
> Dr. Christopher A. Welty                    IBM Watson Research Center
> +1.914.784.7055                             19 Skyline Dr.
> cawelty@gmail.com                           Hawthorne, NY 10532
> http://www.research.ibm.com/people/w/welty
>

Received on Thursday, 16 August 2007 07:45:37 UTC