Re: Friendly amendment to rif:subClassOf

Actually, semantically rdfs:subClassOf is a subrelation of rif:subClassOf.
Not the other way around.


	--michael  


> </chair>
> Here is a hopefully friendly amendment to the proposal to add a 
> rif:subClassOf relation to BLD:
> 
> If we just say that <rif:subClassOf rdfs:subPropertyOf 
> rdfs:subClassOf> I think it goes part of the way in addressing the 
> chief concern of Jos and Dave (which is, as I understand it, that we 
> shouldn't add yet another subclass relation to the semantic web).
> 
> This would make it clear that we are not really creating something 
> new, just imposing a restriction on something already there - in 
> particular all rif:subClassOf relations are also rdfs:subClassOf 
> relations, but not the reverse, and we would say that rif:subClassOf 
> is not reflexive, only holds between classes, etc.
> 
> Less the new name, this is what Jos proposed - to define a suitably 
> restricted subset of RDFS that would be usable for RIF.  I think the 
> new name (rif:subClassOf) helps to make it clear that we do not intend 
> the full rdfs semantics, rather than "hiding" that in the semantics.
> 
> <chair>
> 
> -Chris
> 
> Chris Welty 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 07:42:33 UTC