- From: Brian McBride <bwm@hplb.hpl.hp.com>
- Date: Fri, 18 Jan 2002 12:48:17 +0000
- To: Patrick Stickler <patrick.stickler@nokia.com>, RDF Core <w3c-rdfcore-wg@w3.org>
At 12:39 18/01/2002 +0200, Patrick Stickler wrote: >On 2002-01-14 5:35, "ext Jeremy Carroll" <jjc@hplb.hpl.hp.com> wrote: > > > > I was disappointed that no account was offered of the relationship > > between: > > > > <a> <rdf:type> <rdf:bag> . > > <a> <rdf:_1> <b> . > > <a> <rdf:_2> <c> . > > > > and > > > > <a> <rdf:type> <rdf:bag> . > > <a> <rdf:_2> <b> . > > <a> <rdf:_1> <c> . My understanding of Pat's plan is to get the current version out and then move on to wrapping it up by sorting out containers and reification. I suggest we don't want to delay this till those are done. Brian > > > > My belief is that we either need to offer such an account > > or drop rdf:bagID from the syntax. In certain cases a parser > > may produce either from identical input. > >Sticking my neck out.... > >Perhaps we could do the following, to alleviate this problem: > >1. Define a different closure rule for rdf:Bag and rdf:Alt > which retains the rdf:li (not rdf:_n) relations to members. > >2. Define a closure rule which declares that rdf:_n for every 'n' > is an rdfs:subPropertyOf rdf:li -- so that queries for all > rdf:li statements for a collection will match all rdf:_n > subproperties. > >This captures IMO the fact that rdf:Bag and rdf:Alt are not ordered >but rdf:Seq is, and provides a single membership relation (rdf:li) >for all collection memebers, regardless whether membership relations >are defined in terms of rdf:li or rdf:_n. > >The separate closure rules for rdf:Bag and rdf:Alt will also >preclude separate parsers from generating different, incompatable >graphs. I.e. you'd always get > > <a> <rdf:type> <rdf:Bag> . > <a> <rdf:li> <b> . > <a> <rdf:li> <c> . > >The question of repetition of bag members then depends on >the fact (?) that redundant statements are not merged in a tidy >graph, only their components. > >Thus, > > <a> <rdf:type> <rdf:Bag> . > <a> <rdf:li> <b> . > <a> <rdf:li> <b> . > <a> <rdf:li> <c> . > >Constitutes four distinct statements (triples) and the bag thus >has two instances of <b> in it. But no ordering is defined, as >is the nature of bags. > >The comparable rdf:Seq would have its member relations mapped >to rdf:_n properties according to the RDF/XML serialization >order, and thus, all parsers will produce the identical graph, >as is now the case. > > <a> <rdf:type> <rdf:Seq> . > <a> <rdf:_1> <b> . > <a> <rdf:_2> <b> . > <a> <rdf:_3> <c> . > >Eh? > >Patrick > >-- > >Patrick Stickler Phone: +358 50 483 9453 >Senior Research Scientist Fax: +358 7180 35409 >Nokia Research Center Email: patrick.stickler@nokia.com
Received on Friday, 18 January 2002 07:49:39 UTC