- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Mon, 05 Nov 2001 14:03:43 -0500
- To: danbri@w3.org
- Cc: phayes@ai.uwf.edu, w3c-rdfcore-wg@w3.org
From: Dan Brickley <danbri@w3.org> Subject: Re: closing semantic issues Date: Mon, 5 Nov 2001 13:53:24 -0500 (EST) > On Mon, 5 Nov 2001, Peter F. Patel-Schneider wrote: > > > From: Pat Hayes <phayes@ai.uwf.edu> > > Subject: Re: closing semantic issues > > Date: Mon, 5 Nov 2001 12:13:46 -0600 > > > > [...] > > > > > > In particular, rdf:Bag is not a bag > > > >at all, but instead is much more like a sequence. > > > > > > Right, and that is exactly how the M&S so describes it, by insisting > > > that :_1, :_2 and so on apply to *all* containers. It would be easy > > > to change the MT to describe a different notion than rdf:Bag, but > > > then it would not in fact describe RDF. > > > > > > > If rdf is going to have > > > >something called rdf:Bag, then its *RDF* semantics should conform to the > > > >intended meaning of bags! > > > > > > Its model theory should conform to its intended meaning, but if that > > > intended meaning is not in conformity with a broader notion of 'bag', > > > then don't blame the model theory. What you are complaining about > > > here is an issue in how RDF should treat containers, but its not a > > > model theory issue. > > > > I'm not blaming the model theory at all here. However, I am blaming the > > ``theory'' of rdf:Bag as expressed in M&S. > > > > Let me restate my objection then: > > > > If RDF is going to have something called rdf:Bag, then its *RDF* semantics > > should conform to the generally-accepted meaning of bags, and not to some > > other meaning. If the RDF semantics of this thing do not conform to the > > generally-accepted meaning of bags then it should be given a different > > name. > > [thinks....] > > One way we could do this would be to define a super-property(*) of the RDF > container membership properties (rdf:_1, rdf:_2, rdf:_n). Hmm, not sure > that this delivers exactly what you ask for, but it feels close. I've had > in mind that this would be useful for other purposes too, for example in > RDF/SW apps that need to express queries about containers and their members. > > Dan > > > [*] eg called 'rdf:member','rdf:li' etc. > This works, if you get rid of the _n properties. It doesn't help to have a relationship between an rdf:Bag and its ``members'' called, say, 'rdf:member', as long as you still have rdf:_1, etc. (either explicitly in the input or implicitly). The whole point, as Dan Connolly pointed out, is that <rdf:Bag> <rdf:_1>1</rdf:1> <rdf:_2>2</rdf:2> <rdf:Bag> and <rdf:Bag> <rdf:_2>1</rdf:2> <rdf:_1>2</rdf:1> <rdf:Bag> should be equivalent, that is, a proto-bag that contains (at least) the integers 1 and 2, both with at least single multiplicity. Of course, getting rid of _n still leaves open the strange aspect that you can't ``close'' a bag, but this could be made to work. peter
Received on Monday, 5 November 2001 14:05:22 UTC