Re: MISC: Internet Media Type registration: proposed TAG finding

From: Dan Connolly <connolly@w3.org>
Subject: Re: MISC: Internet Media Type registration: proposed TAG finding
Date: 29 May 2002 20:27:11 -0500

> On Fri, 2002-05-24 at 23:05, Peter F. Patel-Schneider wrote:
> > From: Dan Connolly <connolly@w3.org>
> > Date: 24 May 2002 21:34:31 -0500
> > 
> > > On Fri, 2002-05-24 at 19:09, Peter F. Patel-Schneider wrote:
> > > > From: Dan Connolly <connolly@w3.org>
> > > > Date: 24 May 2002 16:13:32 -0500

[...]

> > Then it is up to you to show how the RDF specification admits cwm and Euler
> > as RDF agents.
> 
> You seem to think it's reasonable for you to introduce a
> term (RDF agent) into the conversation, without defining it,
> then define it later, and then hold me to your definition
> as if I had accepted it.
> 
> I repeat: I don't agree to your definition of 'RDF agent',
> i.e. something that computes inferences that are
> valid per the RDF model theory, and no others.

OK, so I'll make the argument a different way.  See an upcoming message.

[...]

> > Anyone who labels the results as valid RDF consequences is incorrect,
> 
> 'valid RDF consequences' ... another new term.
> I clearly didn't label the results of cwm nor Euler with that
> term; I haven't used it at all in this thread.

That is not a new term.  It is common in logic to refer to the things
entailed (or derviable) in a logic as consequences.

> 'valid RDF consequences' doesn't seem to bring any notions
> into the conversation that aren't captured by 'simple entailment';
> can't we stick to the terms that are defined to our mutual
> satisfaction in documents that are readily available to
> the readership of this forum?

Why?  Why not allow in constructions common to discourse about logics?  

In any case ``simple entailment'' is not the one that should be used here.
Instead ``RDF entailment'' or ``RDFS entailment'' is the appropriate term.
(By the way, the RDF Model Theory may have a typo where it mentions simple
RDF entailment.)

[...]

> > if they know that they should know, is being deceitful.  Anyone who calls
> > the results RDF is verging on deceit.
> 
> Hmm... cwm writes out its results in a format that conforms
> to the RDF syntax spec. That's not RDF? I'm pretty sure
> I don't understand what you mean by 'calling the results RDF'.

Well, having something in RDF syntax does not really make it RDF.  In any
case, by ``results'' above, I mean the inferences performed, which are
definitely not RDF entailments.

> > > > > But yes, the conclusion that "35" is an age of :margaret
> > > > > isn't supported by simple entailment alone, and
> > > > > justification of that conclusion needs to be clear
> > > > > about including the DAML+OIL spec.
> > > > 
> > > > How can this be done in RDF?  It cannot.
> > > 
> > > I disagree.
> > > 
> > > If you had some argument beyond
> > > assertion, we might productively discuss it further.
> > 
> > Well, there is no way in the RDF model theory to entail that two different
> > URIrefs denote the same resource.  The DAML+OIL meaning of UniqueProperty
> > (or whatever the name for making a property be functional is) can be used
> > to DAML+OIL-entail that two different URIrefs denote the same resource.
> > QED
> 
> Hmm... you introduced the term/phrase 'do in RDF' into the conversation;
> now you clarify that you mean 'reach conclusions
> that are simple entailments, and no others'.
> I wish you had said so in the first place.

What else is there in RDF?  Point me to *some* place where there is an
indication that anything besides RDF(S) entailment (not just simple entailment)  
is part of RDF(S).

> My position on media types for the Resource Description Framework
> is that the RDF model theory isn't the end of the story for the
> whole framework; folks that send documents labelled
> with application/rdf+xml (or whatever) definitely license
> all simple entailments. But they also license other inferences,
> based on the vocabulary they choose to use in their document.

This is just crazy.  It is like saying that a document whose media type
indicates that the contents of the document is zero-order predicate
calculus can be treated as if the forall predicate is first-order universal
quantification.

> So just because an agent's inferences aren't simple entailments
> doesn't mean they're false, wrong, deceitful, or unjustifyable.
> On the contrary: I suggest there's an emerging protocol for
> introducing new vocabularies into the framework, and that
> documents labelled with this media type are part of that protocol.

Sure, but then that agent is not doing RDF.

> > > > > > > > Sure, but the non-understood part may completely change the meaning of the
> > > > > > > > other part,
> > > > > > > 
> > > > > > > No, I don't think so...
> > > > > > 
> > > > > > Why not?  What about 
> > > > > > 
> > > > > > 	<fol:negation>
> > > > > > 	  <fol:statement>
> > > > > > 	    <rdf:Person rdf:about="#John">
> > > > > > 	      <loves rdf:resource="#Mary">
> > > > > > 	    </rdf:Person>
> > > > > > 	  </fol:statement>
> > > > > > 	</fol:negation>
> > > > > 
> > > > > I'm not sure how to parse that. If I presume that fol:negation
> > > > > is an RDF typednode, and convert to (something close to) KIF, I get:
> > > > > 
> > > > >   (exists (?n)
> > > > >     (rdf:type ?n fol:negation)
> > > > >     (fol:statement ?n #John)
> > > > >     (rdf:type #John rdf:Person)
> > > > >     (loves #John #Mary)
> > > > >   )
> > > > > 
> > > > > so... ?n is a negation, and it's somehow related to John.
> > > > > I think you meant to express something like
> > > > >   (not (loves John Mary))
> > > > 
> > > > That is indeed what I meant. I expressed it in RDF syntax, which according
> > > > to you, should be perfectly fine.  I used my extension to RDF reasoning,
> > > > which, according to you, should also be perfectly fine.
> > > 
> > > I can't make sense of this extension. Maybe you could explain
> > > how it works a little more generally than this one example.
> > > I don't understand how the fol:negation class's specification
> > > reaches out thru #John to the (loves #John #Mary) triple.
> > 
> > But according to your rules, any method of providing meaning for this
> > extension is adequate.
> 
> No, only those that are monotonic. i.e. when you specify an extension,
> you can only throw out models; you can't put any back in.
> 
> >  OK, the method that I will use is that it means
> > what I mean it to mean.  
> 
> So long as it's monotonic, then you haven't provided an example
> that ...

But monotonic was not part of your rules before.

> > > > > > > > [...] the non-understood part may completely change the meaning of the
> > > > > > > > other part,
> 
> 
> > This is no harder for an RDF-only agent to understand than the DMAL+OIL
> > meaning of daml:UnambiguousProperty.
> > 
> > > In particular, I don't understand it well enough to
> > > see if it's non-monotonic.
> > 
> > Why should this be a problem?
> 
> Because that's against 'my rules'; i.e. the rules I'm
> suggesting for this new media type.

Well, just wait a bit, an example has already been given, and I will be
sprucing it up to make the point clearer.

> > > > > but that's really awkward to do in RDF, but I suppose
> > > > > it could look like:
> > > > > 
> > > > >   <fol:Negation>
> > > > >     <fol:predicateSymbol>http:...#loves</fol:predicateSymbol>
> > > > >     <fol:subjectSymbol>http:...#John</fol:predicateSymbol>
> > > > >     <fol:objectSymbol>http:...#loves</fol:objectSymbol>
> > > > >   </fol:Negation>
> > > > > 
> > > > > where fol:Negation is specified ala:
> > > > > 
> > > > >   (forall (?n ?s ?p ?o)
> > > > >     (<=>
> > > > >       (and
> > > > >         (predicateSymbol ?n ?p)
> > > > >         (subjectSymbol ?n ?s)
> > > > >         (objectSymbol ?n ?o)
> > > > >         (wtr
> > > > >            '(not (holds `(str->sym ?p) `(str->sym ?s) `(str->sym ?o))) )
> > > > >       )
> > > > >       (rdf:type ?n fol:Negation)
> > > > >   )
> > > > > 
> > > > > But even in that case, I *only* eliminate models when I
> > > > > learn the meaning of fol:Negation (i.e. when I add that axiom).
> > > > 
> > > > Yes, and this is no longer RDF.
> > > 
> > > I accept that as your opinion. I disagree.
> > > Argument by assertion is really no fun.
> > 
> > Well, how could it be RDF?  It doesn't match any syntax for RDF.  QED
> 
> 
> Please allow me to clarify; 

I will if you will.  (No joke here, by the way.)

> I might publish, at the address
> of fol:Negation, something ala:
> 
> <rdfs:Property rdf:about="#specInKIF">
>   <rdfs:subPropertyOf rdf:resource="http:.../rdf-schema#comment">
> </rdfs:Property>
> 
> <rdfs:Class rdf:about="#Negation">
>   <specInKIF>
>    (forall (?n ?s ?p ?o)
>      (<=>
>        (and
>         (predicateSymbol ?n ?p)
>          (subjectSymbol ?n ?s)
>          (objectSymbol ?n ?o)
>          (wtr
>             '(not (holds `(str->sym ?p) `(str->sym ?s) `(str->sym ?o))) )
>       )
>       (rdf:type ?n fol:Negation)
>   )
>   </specInKIF>
> </rdfs:Class>

Now you are expecting RDF to encompass KIF?  

This, by the way, is not a rhetorical question.  Although I have my
answer, which is a resounding NO! I want to get your answer on the record,
for all to see.

> Dan Connolly, W3C http://www.w3.org/People/Connolly/

peter

Received on Thursday, 30 May 2002 07:50:35 UTC