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Re: ACTION 20030502#3 gk: review 4.1 of OWL AS&S

From: Graham Klyne <gk@ninebynine.org>
Date: Wed, 07 May 2003 14:30:38 +0100
Message-Id: <5.1.0.14.2.20030507134000.02b7f330@127.0.0.1>
To: Brian McBride <bwm@hplb.hpl.hp.com>, w3c-rdfcore-wg@w3.org

At 13:35 07/05/2003 +0100, Brian McBride wrote:
>At 12:48 07/05/2003 +0100, Graham Klyne wrote:
>
>[...]
>
>
>>Is this really a requirement?  Why is it necessary to map RDF to abstract 
>>syntax?
>
>You have incoming RDF/XML off the wire - is it Owl FULL, DL or Lite?

Ummm... I don't think section 4.1 really helps there at all.

Section 4.2, which I didn't review, has something to say about this.  It 
gives some rules to determine whether some RDF graph is an Owl-lite or 
Owl-DL ontology.  Presumably anything that doesn't satisfy either of these 
criteria is Owl-full.  But the rule is stated in terms of an AS->Graph 
transformation, so I'm not sure they constitute an effective procedure for 
making such a determination.

There's a point that isn't entirely clear to me:
   "the ontologies in O taken together provide a type for every individual ID"
What about mixtures of arbitrary RDF and OWL ontology statements?
Does this mean that every individual must have an explicit type statement?
Exactly what counts as an individual for the purposes of this assertion?

>I was imagining that the abstract syntax might be a good abstraction on 
>which to build an implementation.  So if your implementation is based on 
>the abstract syntax, you'll need to translate incoming rdf/xml into that 
>syntax for processing.
>
>But I'm out of my depth here.  I just noticed that you'd looked at the 
>rules one way round and wondered whether the inverse was significant.

Which suggests, then, that the intended purpose of the mapping tables 
should be spelt out more clearly?  I said up-front that I'm not familiar 
with this stuff, so I just took the material as I found it, without any a 
priori expectation of its use.  That use not being stated, maybe there's 
room here for different guessing?

>>  I guess it's something to do with defining the semantics, but the OWL 
>> AS&S spec claims to contain a semantics based directly on the RDF 
>> triples.  I would assume the mapping (one way or the other) is needed as 
>> part of a proof of equivalence, but I don't see any operational need to 
>> map the RDF triples into OWL AS.
>>
>>>We need to decide what, if any, comment RDFCore wishes to make about 
>>>this aspect of the OWL draft.
>>>
>>>Graham, what is your recommendation?
>>
>>Regarding the OWL AS->RDF triples mapping, I would say:
>>
>>(a) recommend slightly more explanation of the transformation table.  I 
>>think the table itself is probably OK, possibly modulo small 
>>adjustments.  I roughly sketched an example in my previous message, which 
>>could certainly be improved, but which I hope suggests a modest level of 
>>additional detail that would be helpful.
>>
>>(b) that said, I think it's probably OK for proceeding to Proposed REC, 
>>but note that multiple interoperable implementations would be the 
>>appropriate proof-of-the-pudding for moving further along the REC track.
>
>OK - that sounds like no official comment from RDFCore is needed - or 
>would you like WG endorsement?

To be honest, I'm not sure why *any* such comment requires WG endorsement, 
except when there's an abuse of or contradiction with the WG's own 
specifications.  But we were asked to provide review, and I was asked to 
contribute a bit, without being clear (to me) what was the larger 
goal.  The only goal I was aware of was to provide some additional input to 
reinforce or mitigate some aspects of Jan's review.

Which prompts me to look up Jan's comment on this:
[[
4.1
[note] While the abstract syntax naturally associates (via syntactic
nesting) ontologies with all their directives, no such association is
made in teh RDF graph expression of the ontology (apart from
Annotations). I can see why this is the case.

I'm not really sold on the translation table; I think the meaning of it
is unclear. However, I'm stumped as to an alternative compact expression
of the translation into RDF Graph form so feel free to ignore this
comment.
]]
-- http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003Apr/0291.html

I think the association/nesting is captured in RDF in the shape of the graph.

Jan (also) seems to have assumed the table is for "translation into RDF 
Graph form".  I think the table is OK, but would benefit from a little more 
explanation.

#g
--

>>Regarding RDF->AS mapping, if this is really needed, I think more needs 
>>to be said about the selection of triples from an RDF graph.  Once 
>>triples are selected for a given transformation rule, I think applying 
>>the transformation in reverse should be relatively straightforward in 
>>most cases.
>>
>>Since Jan has reviewed the entire document, I'd be interested to hear his 
>>comments on whether I'm looking at the right aspects of this.
>
>And from Jeremy.  Jan may be at xml europe.
>
>Brian

-------------------
Graham Klyne
<GK@NineByNine.org>
PGP: 0FAA 69FF C083 000B A2E9  A131 01B9 1C7A DBCA CB5E
Received on Wednesday, 7 May 2003 09:36:35 EDT

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