W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > May 2003

RE: timbl-03

From: pat hayes <phayes@ai.uwf.edu>
Date: Tue, 6 May 2003 11:56:12 -0500
Message-Id: <p05210603badd97329ed2@[10.0.100.9]>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: <w3c-rdfcore-wg@w3.org>

>  > I personally agree
>>  with Tim that these (type List) triples are redundant, and I would
>>  bet that the OWL stuff, even if it does need them, could be trivially
>>  rewritten so that it did not. I was hoping that we could get back to
>>  Peter and find out whether he thought the problem was serious.
>
>
>Peter punts the problem back to me - since I am the most recent person on
>record as arguing for type triples in general (in OWL DL).
>
>Here are my thoughts:
>
>1: this is merely aesthetic either way
>    People who don't/do want the type triples can have what they want simply
>by not using the rdf:parseType="Collection" syntax (whichever way we
>decide).
>
>2: the triples *are* redundant
>    It is easy to automatically add them; or for that matter, automatically
>remove them.

Adding them is a valid entailment. Removing them is not. There would 
be no reason to remove them if they had not been gratuitously added 
in the first place by special fiat from the syntax rules.

>
>3: the construct was added for OWL, and so the aesthetic judgement as to
>whether they should be there or not in the convenience
>rdf:parseType="Collection" syntax, should be made by WebOnt.
>
>4: Given that in OWL DL and OWL Lite many type triples are needed, it is, in
>my opinion, more aesthetic, to have these type triples also for Lists.

That seems like a VERY weak argument; it is purely aesthetic, and it 
is predicated on a reduction of List to a form of typing, which 
itself is highly arguable in OWL in any case (try selling that line 
to Ian and watch his face carefully). And the disadvantage for many 
other uses of RDF is considerable: the collection syntax - already 
rather overkill for many purposes but likely to be widely used 
because of the incredibly bad job we have done with containers - now 
is obliged to generate 50% more triples than it did formerly, none of 
which provide the slightest extra information. Given that lists are 
likely to be ubiquitous in many 'layerings' on top of RDF, this seems 
to me like a very bad decision for RDF to make on dubious aesthetic 
grounds in OWL.

Seems to me that timbl-03 is a reasonable request which it would be 
trivial for us to comply with and which identifies an error we made, 
or maybe copied from DAML. The only reason to reject it was because, 
we were told, Webont needed us to reject it; and apparently Webont 
does not need us to reject it. So I think we should accept it.

>The
>need for type triples is principally to distinguish the various types of
>user defined in Property in OWL Lite and OWL DL.

But these triples, notably, provide absolutely no functionality of that kind.

Pat


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Received on Tuesday, 6 May 2003 12:56:21 EDT

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