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RE: SEM Solipsistic answers to Peter's entailments and Paradox

From: Smith, Michael K <michael.smith@eds.com>
Date: Sun, 17 Mar 2002 11:43:11 -0600
Message-ID: <B8E84F4D9F65D411803500508BE322140C7ECB5C@USPLM207>
To: Jeremy Carroll <jjc@hplb.hpl.hp.com>, www-webont-wg@w3.org
Help me with this one.  I am definitely missing something.  

> owl:oneOf ( <foo> )
> owl:oneOf ( <foo> <foo> )
> owl:oneOf ( <foo> <foo> <foo> ) ...

This particular example seems to be confusing surface syntax with semantics.
A tool, when asked to return an answer, will not be required to list all
possible equivalent surface syntactic forms.  More to the point, what a tool
does and what the semantics entitle it to do are two different things.

I am assuming that by owl:oneOf we are defining a construct like the
daml:oneOf enumeration.  And that therefore
 owl:oneOf ( x1 ... xn )
will be assigned an interpretation in the model theory that is the SET 
made up of the interpretations of x1 ... xn.  (Assuming a oneOf construct
that is unordered.) 

Having used some variant of set theory to formalize parts of the model we
get all of a set's desirable properties.  The infinite possible expressions
of this set in our surface syntax are by definition identical in the model.
And tools that reason about such things will do their best to canonicalize
expressions so that repetition and ordering don't matter.

This resonates to one of the interesting properties of the RDF model.
Normally we would expect collections to be relatively straightforward to
formalize.  After all, they have been many times. But, RDF is at heart a
scopeless set of arcs (triples) defining a graph. It seems that a set
theoretic interpretation of a collection doesn't graft onto that in a
completely obvious way.  

- Mike

Michael K. Smith
EDS Austin Innovation Centre
98 San Jacinto, #500
Austin, TX 78701
512 404-6683

-----Original Message-----
From: Jeremy Carroll [mailto:jjc@hplb.hpl.hp.com]
Sent: Saturday, March 16, 2002 9:14 AM
To: Jim Hendler
Cc: www-webont-wg@w3.org
Subject: RE: SEM Solipsistic answers to Peter's entailments and Paradox

Jim found a semantically significant typo.


Using this API it is very natural to ask give me all the triples that have
<foo> as subject and <type> as predicate.

[MISTAKE: delete "not"]
It will not be:
- difficult to implement
- and unhelpful to all users

if the correct answer is at least

owl:oneOf ( <foo> )
owl:oneOf ( <foo> <foo> )
owl:oneOf ( <foo> <foo> <foo> )


solipsism provides better answers and a more usable system, and hence a more
useable language.

[[[ (snip)
 but do you mean it will be or it will not be difficult to implement and
unhelpful?  that is I think you mean it is bad to have  the infinite series
of oneOfs as answers, but the above seems to argue you suddenly are in favor
of it -- is this a typo or a conceptual problem on my part?

I think the "not" in "It will not be" was a mistake, sorry.

What I was trying to say is that my understanding of Peter's assumption is
that all the set theoretic consequences of any owl ontology should be
present in all models. While I shared that assumption until the last
telecon, I believe that that presents signification implementation
difficulties, and if we can avoid it in a sound fashion then it is
positively desirable and not merely a way out of a hole.

> p.s. Solipcism would not be my choice for what to call this,

I am quite happy to change the name ... For the sake of this discussion, I
did want an extreme label.
Received on Sunday, 17 March 2002 12:45:21 UTC

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