- From: Richard Cyganiak <richard@cyganiak.de>
- Date: 2009年2月10日 12:42:48 +0000
- To: rick <rick@rickmurphy.org>
- Cc: semantic-web@w3.org
- Message-Id: <A4FE6065-DFF5-4B6B-8A57-77319518F38E@cyganiak.de>
Rick, Let's continue this debate over on the armchair-semantic-web@w3.org list. Cheers, Richard (P.S. it's a joke, I have nothing more to say on this topic) On 10 Feb 2009, at 03:47, rick wrote: > > See below ... > > Richard Cyganiak wrote: >> >> On 8 Feb 2009, at 18:11, rick wrote: >>> As I have written before, the model theory on which the semantic >>> web is based is defined in Alfred Tarski's Semantic Conception of >>> Truth. >> >> Rick, that's overstating the role of model theory on the Semantic >> Web. > > The statement above makes no reference to the ROLE of the model > theory on the semantic web. But I'm glad you raised the issue. This > statement asserts the model theory on which the RDF semantics are > based. And the astute critic of the above would actually claim that > I have understated the model theory by not citing Kripke and > possible worlds. > >> The formal semantics of RDF, as defined in [1], are based on model >> theory. > > Yes, that's my assertion, too. Did you have something more specific > to say about which model theory? Possibly LBase? > >> But a lot of the deployed usage of RDF considers it simply as a >> distributed graph data model, and ignores (or even violates) the >> model theoretic semantics. > > So this statement about the ROLE of model theory raises two > important questions: > > 1. If one is ignorant of model theory, does that invalidate model > theory? > > 2. If one violates the model theoretic semantics of the semantic > web, is the deployed usage part of the semantic web? > > In either case I think there answer is no. > > First, consider music theory as an analogy. If I play two notes B > and F simultaneously on my guitar that form a harmony called a > tritone, but I am ignorant of the music theory of tritones, are > these two notes any less a tritone? I believe my ignorance does > nothing to invalidate music theory. > > Second, the RDF semantics is a W3C recommendation which I understand > is a normative document. In addition, the LBase Working Group Note > defines LBase as the model theory of all semantic web languages. By > definition, any language whose model theory is not LBase is not a > semantic web language. > > Would you suggest the recommendation and note be deprecated to suit > the convenience of usage? > > Again, my claim is that some arm chair philosophizin' would save the > semantic web community some time. I'm not alone in this opinion, but > I suggest that's a decision made by each individual that best suits > their interests and abilities. > >> Various non-RDF technologies, such as Topic Maps or microformats >> are often lumped under the Semantic Web umbrella as well. >> > > So is your claim that RDF technologies and non-RDF technologies that > violate the RDF semantics are part of the semantic web? What then > are the criteria for a semantic web technology? And how many other > technologies are semantic web technologies? > >> So, only a particular part of the Semantic Web technology portfolio >> is based on model theory. I agree, however, that it's the part that >> can benefit most from armchair philosophizing. > > As above, I suspect there's some good debate in drawing the boundary > around what's in this semantic web technology portfolio. Once the > boundary's drawn and there's agreement on questions 1 and 2 above, > let the philosophizin' begin. > >> >> >> Have fun, >> Richard >> >> [1] http://www.w3.org/TR/rdf-mt/ >> >> >>> Briefly, Tarski defines truth in terms of material adequacy and >>> formal correctness. Note that Tarski does not define meaning, only >>> truth. I think everyone would agree that material adequacy applies >>> only to resources can be dereferenced and that it is formal >>> correctness that provides the foundation for inference. >>> >>> So what can we say about meaning on the semantic web? We can say >>> that URIs are definitions, but we need to be clear that meaning is >>> not definition. Quine writes about this in Two Dogmas of >>> Empiricism. Live meaning as referenced above implies interpretation. >>> >>> The question then is whether inference is interpretation. I >>> believe inference as used on the semantic web is necessary, but >>> not sufficient for interpretation. Interpretation as it applies to >>> meaning implies abduction as well as induction and deduction. >>> Inference on the semantic web implies formal correctness and truth. >>> >>> It's not clear whether the semantic web lacks this design >>> principle intentionally, but without this design principle, the >>> semantic web will lag the web in its utility. >>> >>> As a compelling example, consider how the web serves as a meme >>> pool for cultural transmission. How would we expect the semantic >>> web to serve as a meme pool with dead languages ? >>> >>>> I think this worry becomes more so as axioms and systems of >>>> axioms become more complicated. (I just about see similarities >>>> between OWL2 and the Shorter Latin Primer I had at high school). >>>> >>>> A term which is too tightly nailed down in its relationship to >>>> other terms has been dug into an early grave. Having fixed its >>>> meaning, as our world moves on, the term will become useless. >>>> >>> A semiotic domain is a good next step to start developing this >>> flexibility. >>>> The trick, in natural language, is that the meaning of terms is >>>> somewhat loose, and moves with the times, while still having some >>>> limits. >>>> This looseness of definition gives rise to some misunderstandings >>>> (aka interoperability failures), but not too many, we hope. >>>> >>>> >>> Pragmatics is a step after semiotics. >>>> So I wonder, as some people try to describe some part of their >>>> world with great precision, using the latest and greatest formal >>>> techniques, just how long that way of describing the world will >>>> last. Maybe there is a role in such precision in allowing us to >>>> be clear about differences of opinion --- but it doesn't seem to >>>> me to be a good foundation for building knowledge. >>>> >>>> >>> While I agree that we need to recognize the limitations of where >>> we are today, I think Tarski's Semantic Conception of Truth is a >>> pretty good place to start. We also need to recognize the >>> challenges of moving along the path to live meaning. >>> >>> If you're looking for some fun reading, Robert Kent has already >>> defined the Information Flow Framework which parameterizes >>> languages, logics, models and theories into a much more flexible >>> approach than the semantic web. But hold onto your towel ... >>> >>> http://www.ontologos.org/IFF/IFF.html >>>> Perhaps fortunately, I am an engineer not a philosopher! >>>> >>>> Jeremy >>>> >>>> >>>> [1] Don Cupitt, 2001, Emptiness and Brightness, p95 >>>> >>>> >>>> >>>> >>>> >>> >>> -- >>> Rick >>> >>> cell: 703-201-9129 >>> web: http://www.rickmurphy.org >>> blog: http://phaneron.rickmurphy.org >>> >>> >> >> >> >> > > -- > Rick > > cell: 703-201-9129 > web: http://www.rickmurphy.org > blog: http://phaneron.rickmurphy.org > >
Received on Tuesday, 10 February 2009 12:43:32 UTC