- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Wed, 12 Sep 2001 14:29:29 +0100
- To: Martyn Horner <martyn.horner@profium.com>
- Cc: pat hayes <phayes@ai.uwf.edu>, w3c-rdfcore-wg@w3.org
Martyn, This debate has clearly gone beyond the original point that sparked it. I should have changed the subject line -- I think it has more bearing on the nature of the model theory and its interpretations than the terminology (though use of terminology is part of our debate). I don't think we're yet ready to propose a glossary clarification based on our exchange. But I am hopeful something useful will emerge. #g -- At 01:46 PM 9/12/01 +0200, Martyn Horner wrote: >Since I contributed last, Pat and Graham have been going at it >hammer-and-tongs > >See: >GK: http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Sep/0127.html >PH: http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Sep/0130.html >GK: http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Sep/0131.html >PH: http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Sep/0132.html >GK: http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Sep/0061.html > > >I am grateful for the attention paid to this question. > >But, chaps, what I wanted to make was a glossary for the layperson which >would help their initial understanding of some of our terms. I see, >again, how dubious some of these terms are. > >Pat knows, from an exchange which came to nothing probably because I >didn't express myself that well, that I am concerned about what I call >the `temporal coherence' of stuff `on the Web'. This does seem to be an >issue and, I can see, it's an issue which will not disappear just by >defining (and redefining) the words we use. We have to offer to the >newcomer a definition which allows for temporal variance without >completely denying the usefulness and significance of the words. > >For those who haven't been following the thread, much of what has flowed >past has been about the validity of defining a resource at all given its >changing nature (whether incidentally in a changing world or >functionally as a news service, for instance). Graham initially wanted >to point out how separated the ideas of entity and resource were as in, >for example, `today's weather forecast'. Then the discussion started... > >Just to quote some of GK's and PH's dialogue: > >Graham refers me (usefully, thanks) to >http://www.w3.org/DesignIssues/Fragment.html where a distinction is made >between a fragmentid-less URI which refers to a generic document and a >fragmentided URI which refers to an identification within that document >(and not just, as we know, a point in that document :-). Thus no '#' >suggests just generic access and a '#' suggests an identification (eg, >of a resource). Then he says: > >GK: `I find it difficult to unify the RDF idea of a resource (a thing >that is identified) with the general Web idea of a resource (a thing >that is queried or accessed) in light of these comments.' > >Me: So do I, Graham. So do I. I also find it difficult to generalize >this distinction to non-document resources (you know the list, people, >organisations, trees in the park, numbers,...) > >GK: (on the time-variance track) `The approach that I have seen adopted >is to treat such things as sequences of values, or time-varying >functions.' ... `Then, the resource can correspond to the current >weather forecast, but its extension includes the set of all weather >forecasts for all times; the particular member of that extension one >retrieves depends on when the retrieval is performed.' > >Me: Yes. This is why I think it's important to say that a `resource' is >an entity identified by need (if you like), that the act of identifying >it as a resource includes an understanding of such characteristics. This >may not be its most precise definition but it would suggest for a new >reader the role of the concept. > >PH: `As I understand it, the real-world objects *are* resources, so the >idea of being retrievable on the web simply isn't applicable to >resources in general.' > >Me: Retrievability is a characteristic of some resources, of course, but >is not the crucial aspect of their identification even if the identity >of a resource (`today's weather forecast') is expressed in terms of its >retrieval. The resource is identified as `today's weather forecast' and >its usefulness (the `need' for identification) is in its timeliness BUT >the act of retrieval is not what makes it a resource. > >GK: `The alternative view I'm trying to offer here is that real-world >objects are not resources, per se. In addition to the octet-sequences >that are web-retrievable entities, I'm suggesting that the real world >objects are >(also) part of the resource extension I mentioned previously, rather >than the resource directly.' > >GK: `... but such (time-sensitive) semantics would be part of the >semantics of a resource, about which the RDF model theory you have >described seems to be agnostic.' > >Me: Ah-ha! Yes. This is how I think of it. The timeliness of information >belongs in the semantic of that information but should not, in some >sense, invalidate the identification of it as a resource. Again, a >resource is an entity identified as required: the semantics may suggest >that the entity will change. > >PH: `In the meantime however we could also just put this issue off to >the future, and the current MT be thought of as kind of instantaneous >time-slice of this extended temporal semantics.' > >Me: Oh, please, no. Or at least, let me get my glossary done with a nice >clear message for the newcomer while we perhaps agonize about the real >meanings. I don't think we have forced ourselves to consider that RDF >refers to `a time-slice of an extended temporal semantic'... > >The ref >(http://www.ietf.org/internet-drafts/draft-masinter-dated-uri-00.txt) >that Graham includes is a good one, I admit. The idea of a duri: URN >protocol to state that `I am referring to the page as it was then' is, >of course, a valid one but it does not fit in with the requirements of a >practical Semantic Web. Larry has it right but it's not going to help. >It's great for putting in legal documents. However, the Semantic Web is >going to have to cope with time-variant data and not just deliberately >time-variant (like today's weather) or with time-variance created by >retrieval or time-variance due to decay. > >Help. What shall we tell the novice? `Resource' (and its relationship to >`entity') must be in the vocabulary of anyone starting to read the RDF >documentation. I'd have thought it completely reasonable that some >kernel of meaning can be attached to these words before such a reader >has to face that the `true' meaning has certain unclear aspects. > >Do my definitions suffice, I still wonder... > >-- >Martyn Horner <martyn.horner@profium.com> >Profium, Les Espaces de Sophia, >Immeuble Delta, B.P. 037, F-06901 Sophia-Antipolis, France >Tel. +33 (0)4.93.95.31.44 Fax. +33 (0)4.93.95.52.58 >Mob. +33 (0)6.21.01.54.56 Internet: http://www.profium.com ------------------------------------------------------------ Graham Klyne MIMEsweeper Group Strategic Research <http://www.mimesweeper.com> <Graham.Klyne@MIMEsweeper.com> ------------------------------------------------------------
Received on Wednesday, 12 September 2001 09:33:21 UTC