- From: Pat Hayes <phayes@ihmc.us>
- Date: Sat, 9 Apr 2011 08:49:56 -0500
- To: William Waites <ww@styx.org>
- Cc: Richard Cyganiak <richard@cyganiak.de>, Ivan Herman <ivan@w3.org>, RDF Working Group WG <public-rdf-wg@w3.org>
On Apr 9, 2011, at 7:28 AM, William Waites wrote: > * [2011-04-09 13:09:15 +0100] Richard Cyganiak <richard@cyganiak.de> écrit: > > ] ISSUE-25 is about the RDF reification vocabulary, which is a > ] built-in vocabulary for reifying *statements*. You are talking > ] about a common modeling practice in domain vocabularies for > ] reifying *relationships*. That has nothing to do with ISSUE-25. > > Right, that was what I wanted to have explicitly clear. It's not the > idea or practice of reification that is to be deprecated but the > baked-in support for reifying binary relations. No, really, you have this wrong. It IS the idea of reification that is being deprecated; and this device that you have mentioned, of encoding an n-ary relation using a bundle of binary 'role' relations, is NOT reification. The two things are distinct. Using the name of one to refer to the other is going to cause a lot of confusion. Reification is using RDF to *describe* other pieces of RDF. > > Whilst I support this, I think the distinction between *statements* > and *relationships* is highly artificial. A statement is just a binary > relationship. WRONG! A relationship is, well, a relationship. Formally, it is a set of pairs of things. A statement is something that asserts that a relationship holds between some things (or it can be more complicated, of course). The statement that, say, PatHayes owns 121HIghPinesPlace asserts that the relationship *owns* holds between the pair of things <PatHayes, 121HIghPinesPlace>. The statement uses a relationship name and mentions the relationship, but it is not the same thing as the relationship. > The only reason the number 2 is special and the reason > that RDF is not prolog, is because it is the smallest arity in which > you can expres arbitrary arity relations *if you use reification*. No, it is special because it is the smallest arity in which you can express arbitrary relationships if you can share names between atomic sentences, so you can say things like a R1 b & b R2 c & c R3 d ... or like a R1 b & a R2 c & a R3 d ... Either pattern (and others) can be used. But none of this has anything to do with reification. (BTW, if you restrict things so that you can only share a name once then you need triadic relations, which Pierce in around 1880 thought was terribly significant: trinities and all that.) Pat > Because 2 is special we have a special vocabulary for dealing with it, > but that turns out not to be especially useful because there's direct > support in the language for it, and the remaining use for it, > provenance, we have better ways of handling. > > Cheers, > -w > -- > William Waites <mailto:ww@styx.org> > http://river.styx.org/ww/ <sip:ww@styx.org> > F4B3 39BF E775 CF42 0BAB 3DF0 BE40 A6DF B06F FD45 > > ------------------------------------------------------------ IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Saturday, 9 April 2011 13:50:51 UTC