Re: Friendly amendment to rif:subClassOf

Thinking more about Chris' proposal, I think it may make people more open
to the idea. I do not thing we need to introduce rdfs:subclassOf
explicitly, but we could explain that rif:subclassOf is a subrelation of
rdfs:subclassOf, which is non-reflexive. And the reason is to enable
exchange of models that use such non-reflexive subclasses.

By the way, in the F-logic paper (not in the implementations of F-logic)
the subclass relationship *is* reflexive. The reason is that this
simplifies the proof theory.

Theoretically it does not matter if the relation is reflexive or not. With
equality op and the != ops one can define one relationship using the other.
But in practical systems such a reflexive relation proved to be inconvenient.
In queries one had to constantly say "?X is a subclass of ?Y and ?X != ?Y".
If we use the RDFS version, this is what people will have to do.

For RIF, the implication is even worse, since the motivation for
rif:subclassOf is to support exchange of models. Since most languages use
the non-reflexive notion of subclassing, they would not be able to use
rif:subclassOf (if the latter is the same as rdfs:subclassOf).


	--michael  



> On 16 Aug 2007, at 16:04, Jos de Bruijn wrote:
> 
> > <snip/>
> >
> >>> rif:subclassOf is not a new concept. It is there in
> >>> every standard OO language. Jos' arg was that it is a new word in  
> >>> the
> >>> vocabulary, and Dave was questioning whether RIF should define  
> >>> such a
> >>> concept (incl. rdfs:subclassOf) in the first place.
> >>
> >> I'm just hoping it makes what you proposed a little more  
> >> palatable. But
> >> let's see - Dave and Jos?  Does Michael need still more coffee or  
> >> do I?
> >
> > My argument was that there are already semantic Web languages for
> > defining ontologies (including the subclass relation), so that RIF
> > should probably not invent a new vocabulary for defining ontologies  
> > (or
> > classifications), but rather show how existing vocabularies for  
> > ontology
> > definition (including (subsets of) RDFS) can be combined with the RIF.
> [snip]
> 
> If rif:subClassOf turns out to be too contentious, one might choose a  
> different name e.g., rif:subType, or something like that.
> 
> (I personally might have preferred something like "subSetOf" for rdfs  
> and owl subsumption, but it wasn't up to me and my time machine is on  
> the fritz again.)
> 
> (I know that the "rif" is supposed to make all the difference in the  
> world, and of course, rif:subClassOf is a different symbol; I just  
> can imagine furor over it; if such furor comes, a simple renaming is  
> an option.)
> 
> Cheers,
> Bijan.
>

Received on Thursday, 16 August 2007 15:46:29 UTC