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RE: question: datatype reasoning?

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Fri, 24 Jan 2003 09:34:21 +0100
To: "Jim Hendler" <hendler@cs.umd.edu>, "webont" <www-webont-wg@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDIEABCBAA.jjc@hpl.hp.com>


My understanding is as follows:

There are many difficult cases
e.g.

<p> range xsd:negativeInteger
<p> range xsd:byte

DL-entails

owl:Thing owl:sameClassAs
  restriction(p, maxCardinality=128 )

There are worse cases when we are considering potential compatible types
that do not have the same primitive base type (e.g. try xsd:float instead of
xsd:byte). Such cases are in need of clarification from XML Schema WG.
Nasty questions that can be asked in OWL DL assuming floats and decimals
share the same underlying real values is how many floats are unsignedLongs
(algorithm is keep increasing the maxCardinality in an entailment like that
above until the entailment does not hold).


I am not sure that there can be an effective OWL DL reasoner that cannot
reason about the cardinalities of sets of individuals, and hence it may also
need the ability to reason about the cardinalities of sets of datatypes (as
in the above example).
OWL Lite is largely rescued from this by restriciting cardinalities to 0 and
1. A complete OWL Lite reasoner would I suspect need to simply know the
intersection lattice of the XML Schema builtin datatypes and which
intersections are empty and singleton.

e.g.

<p> range xsd:nonNegativeInteger
<p> range xsd:nonPositiveInteger

Lite-entails

owl:Thing rdfs:subClassOf
  restriction(p, maxCardinality=1 )

or

<p> range xsd:unsignedByte
<p> range xsd:nonPositiveInteger
<i> rdf:type restriction( p, minCardinality=1 )

Lite-entails

<i> <p> "0"^xsd:int

OWL with user defined datatypes (that we want) is worse.
OWL Full (with or without user defined datatypes) is much worse.

I was planning on adding such tests under the datatypes issue.

see:
http://lists.w3.org/Archives/Public/www-archive/2002Nov/att-0092/02-index
for long discussion of these issues (RDF not OWL)


Jeremy


> -----Original Message-----
> From: www-webont-wg-request@w3.org
> [mailto:www-webont-wg-request@w3.org]On Behalf Of Jim Hendler
> Sent: 24 January 2003 03:26
> To: webont
> Subject: question: datatype reasoning?
>
>
>
> I was asked the following by a colleague, we tried to find the answer
> in the Semantics document, but we couldn't quite work out the
> details.  Question is, does a complete Owl Lite or DL reasoner have
> to do complete datatype reasoning?  i.e. for all the XML schema
> primitive types, does a complete OWL reasoner have to be able to do
> the correct class reasoning, etc -- knowing integers are numbers,
> URIs are strings, etc. and appropriately applying these.
>   If the answer is that an OWL system must do so, do we have any
> implementation evidence to offer in this space?  If we don't expect
> complete datatype reasoning, what level of such do we expect, and
> where will we specify it (document-wise)
>   thanks
>   JH
>
>
>
>
> --
> Professor James Hendler				  hendler@cs.umd.edu
> Director, Semantic Web and Agent Technologies	  301-405-2696
> Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
> Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
> http://www.cs.umd.edu/users/hendler
>
>
Received on Friday, 24 January 2003 03:34:40 GMT

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