- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Thu, 30 May 2002 07:49:47 -0400
- To: connolly@w3.org
- Cc: phayes@ai.uwf.edu, danbri@w3.org, www-rdf-logic@w3.org
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