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Re: TEST: FunctionalProperty InverseFunctionalProperty 3.4 4.1

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 01 Aug 2002 19:32:57 +0100
Message-ID: <3D497ED9.2050502@hpl.hp.com>
To: Ian Horrocks <horrocks@cs.man.ac.uk>
CC: Jeremy Carroll <jjc@hplb.hpl.hp.com>, www-webont-wg@w3.org



Ian Horrocks wrote:

> On July 26, Jeremy Carroll writes:
> I am also concerned about tests in the style of FunctionalProperty
> test 003. Here, we are asked to conclude that a property is
> InverseFunctional given that its inverse is functional. This is a
> higher order inference that is a consequence of the semantics of OWL,
> but cannot be proved within OWL. I.e., OWL does not state anything
> like:
> 
> forall P,Q . FunctionalProperty(P) ^ inverse(P,Q) -> InverseFunctionalProperty(Q)
> 
> I would *NOT* expect an OWL reasoner to find this inference.
> 



I could support this as a non-entailment test.

As soon as we have an interesting divergence of views it behoves
to make up our minds and choose either an entailment test or
a non-entailment test.


i.e. instead of the comment:

<!--
  If prop is an owl:FunctionalProperty,
  then its inverse is an owl:InverseFunctionalProperty.
-->

We could have the comment

<!--
  If prop is an owl:FunctionalProperty,
  then its inverse, while being constrained to be
  consistent with being an owl:InverseFunctionalProperty
  should not be deduced as being one.
-->


i.e. from

http://www.w3.org/2002/03owlt/FunctionalProperty/premises003.rdf

it does not follow that

http://www.w3.org/2002/03owlt/FunctionalProperty/conclusions003.rdf


This would fit with my preferred reasoning style in which the statements
such as


:inv a owl:InverseFunctionalProperty .

are within the domain of discourse, and have semantic import over and above
their definition, which is a necessary but not sufficient condition.

As far as I can see, the non-entailment test follows from a
Connolly/solipsistic/DAML+OIL axiomatic style of semantics

whereas the entailment test reflects a Patel-Schneider view of the
world in which the definition is a neecessary and sufficient condition.


Jeremy
Received on Thursday, 1 August 2002 14:33:33 GMT

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