- From: rick <rick@rickmurphy.org>
- Date: Tue, 10 Feb 2009 09:58:23 -0500
- To: semantic-web@w3.org
Thanks Richard, Good humor is often missing from lists and I enjoyed the laugh! Richard Cyganiak wrote: > > 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 >> >> > > > > -- Rick cell: 703-201-9129 web: http://www.rickmurphy.org blog: http://phaneron.rickmurphy.org
Received on Tuesday, 10 February 2009 14:59:33 UTC