- From: Axel Polleres <axel.polleres@urjc.es>
- Date: Wed, 28 Jun 2006 01:07:49 +0200
- To: "Hirtle, David" <David.Hirtle@nrc-cnrc.gc.ca>
- CC: Chris Welty <cawelty@frontiernet.net>, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>
Hirtle, David wrote: > Hi Chris, > > >>The word "intensional" is being used in a way that I am >>unfamiliar with. The text seems to imply that intensional == >>implicit (which is isn't), and is contrasted with "factual" >>which is equated with "extensional" (which it also isn't). > > > The use case is heavily based on Axel's > http://www.w3.org/2005/rules/wg/wiki/UCR/Candidate_Use_Cases_for_2nd_Dra > ft/PublicationAlternative > > and the intensional vs. extensional distinction came from there. Axel > explained it in an earlier email as: > > This goes along with the notion in deductive databases to distinguish > between extensional (facts) and intensional (rules) knowledge. This terminology is common in DB textbooks and surveys, where stored factual knowledge is called intensional database (EDB) whereas views, i.e. implicitly defined knowledge is called the "intensional database" (EDB). Since the example was meant to demonstrate exactly this, that rules can provide for defining metadata as such non-materialized views, I still find the term appropriate, see e.g. H. Gallaire, J. Minker, and J. M. Nicolas. Logic and databases : a deductive approach. ACM Surveys, 16(2), 1984. >>The text also seems to imply that e.g. "Every science fiction >>movie is a movie" is implicit and intensional - but the mere >>fact of saying it makes it explicit, so I'm really not sure >>what you mean. I mean that this rule makes whenever you give a fact: X is a sciFiMovie. then you implicitly also define the fact X is a movie. without the need to make this explicit. Clearly this very simple form of implicit knowledge can already defined using, e.g. RDFS, but not the more involved rules such as "All movies listed at http://alternativemdb.example.org/ are independent movies" and extensions thereof, where the source (context) where the metadata comes from plays a role, etc. > Well, "Every science fiction movie is a movie" *is* implicit, until > being made explicit by rules... > >>Unless I'm missing something, this does not correspond to any >>meaning I know, or can find, of intensional (or extensional, >>for that matter). I don't think "intensional" or "implicit" >>is what you want here, so I suggest not confusing a reader >>with obscure terminology that is used incorrectly. > > Whether used correctly or not, I agree that it's probably not necessary > to the use case. Now as you say it, the only argument that could count against IDB/EDB distinction might be that it is slightly misinterpretable, since in the deductive database use, EDB/IDB are often viewed disjoint IIRC, which is too restrictive in general... >>To be constructive, how about something like, "Publishing >>rules for interlinked metadata" > > I'd be fine with this, but let's see what Axel has to say. I am not religous about these terms, although I thought they properly describe what I wanted to say. best regards, axel >>-----Original Message----- >>From: public-rif-wg-request@w3.org >>[mailto:public-rif-wg-request@w3.org] On Behalf Of Chris Welty >>Sent: Monday, June 26, 2006 11:05 PM >>To: Public-Rif-Wg (E-mail) >>Subject: [UCR] The Use Case previously known as publication >> >> >> >>Specific comments on the new text for Use Case 2.10: >> >>The word "intensional" is being used in a way that I am >>unfamiliar with. The text seems to imply that intensional == >>implicit (which is isn't), and is contrasted with "factual" >>which is equated with "extensional" (which it also isn't). >>The text also seems to imply that e.g. "Every science fiction >>movie is a movie" is implicit and intensional - but the mere >>fact of saying it makes it explicit, so I'm really not sure >>what you mean. >> >>Unless I'm missing something, this does not correspond to any >>meaning I know, or can find, of intensional (or extensional, >>for that matter). I don't think "intensional" or "implicit" >>is what you want here, so I suggest not confusing a reader >>with obscure terminology that is used incorrectly. >> >>I realize "intensional" is a fairly slippery concept, and I >>don't want to get the WG bogged down in defining it. >> >>To be constructive, how about something like, "Publishing >>rules for interlinked metadata" >> >>-Chris >> >>-- >>Dr. Christopher A. Welty IBM Watson Research Center >>+1.914.784.7055 19 Skyline Dr. >>cawelty@frontiernet.net Hawthorne, NY 10532 >>http://www.research.ibm.com/people/w/welty >> >> >> >> > > > -- Dr. Axel Polleres email: axel@polleres.net url: http://www.polleres.net/
Received on Tuesday, 27 June 2006 23:08:33 UTC