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Re: daml:collection

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Fri, 5 Apr 2002 18:16:59 -0600
Message-Id: <p05101513b8d3e7f92c3d@[65.217.30.94]>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: w3c-rdfcore-wg@w3.org
>Folks,
>
>At the last SW coordination group telecon the WEBONT folks indicated 
>that removing daml:collection would be a problem for them.

Im not sure what that means. That is, daml:collection is part of the 
DAML namespace, right? Not part of RDFS. So what has it got to do 
with us? Do we even have the authority to remove something from 
someone else's namepsace?

>  Consequently we agreed that the WEBONT chairs would solicit two 
>volunteers from WEBONT to work with RDFCore to identify to figure 
>out what they need and see if we can work out a solution.  I believe 
>that DanC and Jos volunteered.
>
>As I understand things, the key requirements are:
>
>   o a compact and relatively conventient xml syntax
>   o a way to represent a closed collection, i.e. our present 
>understanding of issue * rdfms-seq-representation
>
>I understand it is not a requirement that the resulting RDF graph 
>structure is a list.

I bet they will get into a terrible mess if they only have unordered 
collections.

>Of course I defer to the WEBONT folks to state their requirements; 
>I'm saying this just to get things started.
>
>Amongst the possible solutions, the ones I can see are:
>
>   o bless daml:collection as defined as part of RDF

Yuk.

>   o WEBONT define a syntactic transform which turns whatever syntax 
>they choose into regular rdf syntax before RDF sees it

Again, they will do that anyway, right? That is, it is up to WEBONT 
to map their syntax into RDF triples, surely: not up to us to do it 
for them. We just have to give them the tools adequate to do the job.

>   o RDFCORE defines a way of closing RDF's existing containers; 
>Pat's suggestion of an end marker as that is closer to a list 
>structure and doesn't involve integers (datatypes aghhhhhhhhhhhhhh!)

To emphasize, we don't really need to close RDF containers. We only 
need to be able to provide WEBONT with a way for them to *treat* 
their uses of RDF containers as closed.

>   o WEBONT defines a way of closing RDF's existing containers

Right, exactly. That is what my proposal was, in fact. Then we don't 
have to do anything :-)

Pat

PS. So here is the formal proposal we make to WEBONT. We say that

1. Whereas WEBONT needs to encode complex syntactic structures in RDF 
triples, and requires some structuring primitives to enable it to do 
that; and
2. Whereas the current RDF container model is apparently inadequate 
for this task, by virtue of the there being no way to mark the end of 
a container or specify an exact size for the container; and
3. By virtue of the fact that to provide such a facility in RDF would 
be a major change to the RDF language and data model, effectively 
introducing a form of negation into the language, and would therefore 
be an unacceptable burden to the RDF core WG;
THEREFORE
4. The RDF core WG respectfully suggests to the WEBONT WG that it 
adopt the following CONVENTION: that for purposes of WEBONT, a 
particular individual be chosen to be the end-of-syntactic-container 
entity, by analogy with NIL in LISP; and that for WEBONT purposes, 
any RDF container used for syntactic encoding of WEBONT expressions 
(or for whatever other purposes that WEBONT shall, in its total 
discretion, decree to be of utility to itself) shall be understood to 
contain only those elements which are lower, in the RDF ordering 
defined by the numerical indices of the RDF container properties, 
than the index of the lowest-numbered occurrence of said particular 
individual.


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Received on Friday, 5 April 2002 19:16:57 EST

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