- From: dehora <bill@dehora.fsnet.co.uk>
- Date: Fri, 18 May 2001 01:59:01 +0100
- To: "pat hayes" <phayes@ai.uwf.edu>
- Cc: <www-rdf-logic@w3.org>
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 : dehora : >I think that these two are not at all the same: : > : >1: RDF reification is a technique to make statements about : >statements. : > : >2: KR reification is a technique for objectifying a statement. : : pat hayes : These seem to me to be clearly identical. Maybe you mean something : more by 'objectifying' than I do, but calling something an 'object' : (or an 'entity') in KR simply means that it is considered to be in : the semantic domain of description, and this is exactly what is : implied by saying that one is making statements about it. Objects : *are* things that one makes statements about (actually, it would be : better to say, things that one could make statements about, but thats : a technical quibble.). : : Maybe you could elaborate on what you see as the distinction here? I'll try. I made 2 mistakes at least. First (my bad), I should have said this: 2: KR reification is a technique for objectifying relations. Second, I mixed up reification and mentioning (and then proceeded to waffle on about the difference...oh dear). Though I claim that this is easy to do in RDF. I don't know enough to say whether reification itself is a dud for RDF. In my KR102 class and in the 2 or 3 books I have that mention reification, it came across as a technique to allow a language to refer to its categories which are sometimes treated as predicates, like dotcom(shop.com), and offers a trick that allows you to say titsup(dotcom, shop.com) and treat the predicates as terms in the language. And stuff like genus/inheritance using isa() and ako() becomes available as you go. Now, I don't think RDF statements are categories that can be treated like this for the most part, which is why I say that reification over them isn't like KR reification. Then again, I found KR102 tough going. However my real beef as an implementer is with the 4 triples that make up an RDF reification, not with the use of a URI acting as a reified statement. How about this; all imho: 1: RDF reification is a technique that turns statements into URIs. 2: KR reification is a technique that turns predicates into terms. in RDF: 3: a statement is not a predicate. 4: a statement is not a resource. 5: a predicate is a resource. 6: a resource clearly doesn't need to be reified to have a statement made about it. 7: excluding literals, things that are not resources cannot have statements made about them. 8: a reified_statement is a resource. 9: a _reification consists of 4 statements, which share a reified_statement. so I'm inclined to say: 10: RDF and KR reifications are not the same or at least not operating on the same stuff. 10.a: a _reification is not an object. 10.b: a reified_statement is an object. and inclined to believe that: 11: I want to be able to nest statements, especially queries. 12: I want to be able to hang properties off statements. 13: I might want to reify statements. Who knows. 14: I'd like to mention a statement with having to make a _reification. 15: I'd like to reify a statement with having to make a _reification. 16: I'd like to hang properties off a statement with having to make a _reification. 17: I'd like to be able to get my software to easily distinguish between 15,16,17. 18: Bookkeeping _reifications in software is a hassle I could live without. 19: In fact the thing I like least about RDF as an implementer are _reifications. 20: I've suggested a tacky way to avoid _reifications using literals. 21: Jonathan Borden's query syntax proposal has better articulation, has real legs. regards, Bill - ---- Bill de hOra : InterX : bdehora@interx.com -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 7.0.3 for non-commercial use <http://www.pgp.com> iQA/AwUBOwRy4+aWiFwg2CH4EQJzbwCeLW0mKpQqSFbMm2ZaLOIDcIrKYCIAmwfa qg1GGb7zoPL242draVhPLVic =eMK3 -----END PGP SIGNATURE-----
Received on Thursday, 17 May 2001 20:59:22 UTC