- From: Pat Hayes <phayes@ihmc.us>
- Date: 2010年1月14日 14:29:18 -0600
- To: Steve Harris <steve.harris@garlik.com>
- Cc: Dan Brickley <danbri@danbri.org>, Danny Ayers <danny.ayers@gmail.com>, Semantic Web <semantic-web@w3.org>
- Message-Id: <C0DCF641-7C4E-40BC-8033-18602E4EB2B8@ihmc.us>
On Jan 14, 2010, at 1:10 PM, Steve Harris wrote: > On 14 Jan 2010, at 17:31, Dan Brickley wrote: > >> On Thu, Jan 14, 2010 at 4:20 PM, Pat Hayes <phayes@ihmc.us> wrote: >>> A lot, perhaps all, of this hair could be avoided if RDF allowed >>> general >>> tuples as well as triples. All that is needed is some way to put N >>> things >>> into a sequence: so, put N things into a sequence. The 'graph >>> model' would >>> be a hyperlink, drawn as a polygon (eg triangle for N=3) rather >>> than a line. >>> In triples-style syntax, it would just be moving a dot. >> >> I periodically wonder what an RDF without the binary restriction >> would >> look like. >> >> Would each property/relation have a fixed arity, eg. dc:source might >> 'be a 4', 'foaf:knows' a 7? That doesn't make a lot of sense to me. >> So >> presumably they'd vary freely. In which case, we have a lot of >> figuring out to do when wondering whether livesWith(alice, bob, >> 2007, 'y') implies livesWith(alice,bob) or livesWith(alice, bob, 'y', >> 'foo.html'). The binary straightjacket makes some of these questions >> impossible, albeit maddeningly... > > I was thinking something more like a new literal type, which was a > list/vector/sequence/whatever-you-want-to-call-it. > > So, it would still bind in a query: > > [using the old list syntax for the sake of an example] > <a> <b> (1 2 3) . > > SELECT ?z > WHERE { > <a> <b> ?z . > } > > and the return value would be a list "literal". But are these necessarily literal values. then? I don' t think that would be enough. I wonder about query binding, I think it would be more use to allow item binding, with a wildcard pattern variable extending SPARQL. We followed this idea in Common Logic and it is very slick. So for example :a :P ?x . matches :a :P :foo . with ?x/foo, but does NOT match :a :P :foo :baz . However, :a :P ??x . (choose your own syntax: CL uses ...x) matches both of them with ??x bound to (:foo) (not :foo, note: the list, not its atom) in the first case and (:foo :baz) in the second. This lets a query bind an arbitrarily long tail but also allows queries to micromanage things inside argument sequences when required. Some care is required to ensure a unique match, but its workable and very convenient. Pat > > - Steve > ------------------------------------------------------------ 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 Thursday, 14 January 2010 20:30:25 UTC