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Re: TEST: please do Nothing

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Tue, 24 Sep 2002 01:10:47 +0100
Message-ID: <15759.44423.204980.380852@merlin.horrocks.net>
To: Jeremy Carroll <jjc@hpl.hp.com>
Cc: www-webont-wg@w3.org

On September 23, Jeremy Carroll writes:
> 
> 
> (owl:Nothing)
> Or Thing, or cardinality or one of the other OWL features.
> 
> One of my hopes with doing the Test form:
> http://sealpc09.cnuce.cnr.it:8080/wowg/jsp/edit.jsp
> 
> is that the members of the TEST focus area (myself, Dan Connolly, Jonathan 
> Dale, Mike Dean, Libby Miller, Jos De Roo, Michael Sintek) and any other WG 
> members, might find it easier to produce tests - particularly aiming to get 
> coverage of OWL features. Most of them look straightforward e.g:
> 
> Nothing
> sameIndividualAs
> differentIndividualFrom
> samePropertyAs
> sameClassAs
> cardinality, minCardinality, maxCardinality
> hasValue
> someValuesFrom
> allValuesFrom
> unionOf
> intersectionOf
> 
> Producing one or tests for each of these would be good.
> It would be nice to have tests that illustrate the basic meaning and some easy 
> misconceptions.

I believe we also need some tougher tests, and in particular tests
that show up subtle distinctions between entailment and
non-entailment. I already provided a number of examples of such test
(admittedly not in the relevant format).

A nice example testing the interaction of functional properties with
property subsumption is the famous "W" case. E.g., we have 5
functional properties, with P1 subsuming both P3 and P4, and P2
subsuming both P4 and P5. If an object x is related via P3 and P5 to y
and z respectively, then (in the absence of other information) we can
deduce that y and z are the same individual iff we know that x is also
related to something via P4.

By the way, it is not desirable for tests always to use individuals,
as in many applications reasoning with classes will be enough (and
reasoning with individuals is in general much harder, or at least much
less tractable). The above example also works perfectly well for
classes. I.e., in the absence of other information, the class of
things that have (someValueFrom P3 C) and (someValueFrom P5 (not C))
is NOT inconsistent, but the class of things that have (someValueFrom
P3 C), (someValueFrom P5 (not C)) and (someValueFrom P4 Thing) IS
inconsistent.

Ian

> 
> e.g.
> Nothing
> <a> rdf:type owl:Nothing .
> is inconsistent.
> 
> e.g.
> the cardinality lot, crib something from FunctionalProperty tests.
> 
> e.g.
> hasValue a simple entailment showing that belonging to the restriction entails 
> having the value
> a non-entailment shoing that belonging to the restriction and having some 
> other value does not mean that the two values are equal.
> 
> e.g.
> unionOf
> Well we have to have the student/employee example! I guess we are coming round 
> to trhat being an entailment rather than a non-entailment.
> 
> Tests that are received before the end of the week will get into the test 
> document to be reviewed.
> 
> 
> Jeremy
Received on Monday, 23 September 2002 19:13:30 GMT

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