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Re: TEST: Functional and InverseFunctional tests for approval

From: Christopher Welty <welty@us.ibm.com>
Date: Tue, 3 Sep 2002 11:47:42 -0400
To: "Jeremy Carroll" <jjc@hpl.hp.com>
Cc: www-webont-wg@w3.org
Message-ID: <OFBC6A8EE0.20895DC9-ON85256C29.0051774E@pok.ibm.com>

Jeremy,

I found Peter's alternative test case much easier to understand.  I 
couldn't make heads or tails of the one you originally posted.  This is 
likely because I don't understand the syntax you used.  While Peter's 
syntax was clearer to me, I don't know what variant that was.  Is there 
anything wrong with the test case Peter posted?  What do you call the 
syntactic style of it?  (sorry for the naive questions)

There are other entailments that should follow from FunctionalProperty, 
even if we consider the feature in isolation.  Should there be a test case 
for each one?  These have to do with the equivalence of FunctionalProperty 
and (MaxCardinality 1), subsumption tests, and also the relationship 
between FunctionalProperty and InverseFunctionalProperty.

-Chris






"Jeremy Carroll" <jjc@hpl.hp.com>
Sent by: www-webont-wg-request@w3.org
09/01/2002 02:01 AM

 
        To:     <www-webont-wg@w3.org>
        cc: 
        Subject:        Re: TEST: Functional and InverseFunctional tests for approval

 



Peter I am very sorry but I missed your earlier contentful message about
these test cases:

http://lists.w3.org/Archives/Public/www-webont-wg/2002Aug/0226.html

In light of that, I overreacted to your continued opposition to these test
cases at the telecon, sorry.

I reply to  that message here.


>> DESCRIPTION
>>
>>  If prop is an owl:FunctionalProperty,
>>  and a resource has prop arcs pointing to two
>>  different URIrefs, then those two URIrefs denote the
>>  same resource, and hence each have the same properties.

Peter:
>This description mixes syntax and semantics, and thus need to be 
rewritten.

In defence of the comment, I don't think the mixing introduces 
difficulties
of understanding; but I agree with you on stylistic grounds.

It would have been helpful if you had suggested alternative text.

How about:
[[
If prop is an owl:FunctionalProperty,
then any resource has at most one prop value.
Thus if a single URIref is described with
two different prop arcs with objects which
have two different URIrefs, then those two URIrefs
denote the same resource; and hence each have the
same properties.
]]

It's longer, is the extra length necessary?
Is it clearer?

>This test is actually a test of two things:
>1/ Functional properties are partial functional.
>2/ If two different URIrefs denote the same object, then statements that
>   have the first as a subject can also be written using the other.

Yes. I did not want to use sameZZZAs in the conclusions, so that
syntactically I was testing just one aspect of owl. But you are right to
point out that then semantically I am testing two aspects. (One aspect of
owl, your point 1; one aspect of RDF, your point 2).

I think this is correct design, in that at least some of our readers and
implementors understand RDF; hence this test is only testing point (1) and
RDF.

>RATIONALE
>
>  This is one of the basic tests of the entailments related to the 
various
>  different kinds of OWL properties.

Thanks. I think this is the intended rationale for half the tests, and the
other intended rationale is "This test illustrates the resolution for 
issue
ZZZ".
As such I think those two rationales are largely redundant. (Although we
need to clearly present which tests relate to which features and which 
tests
relate to which issues).

I think we should take these two rationales as read, and only include a
rationale for some other sort of test.

>I would actually prefer that RDF/XML not be used at all in the
>documents used to define tests, on the grounds that RDF/XML is too
>difficult to read.

While I have sympathy I am not sure where to go with this.
I think the most readable syntax is N-triple with QNames.
(N-triple being too verbose).

We could choose to present our tests in such a syntax, but that then gives
us issues about where the syntax is presented, define etc. N3 is, IMO,
unusable for a spec because there is no well-defined standard stable
definition.


Your final point, except for the repeats arising from the repeats in the
test; is to do with xml:base.

1. I made a typo error in applying an earlier comment from Dan to the 
first
test.
It says:
  xml:base="http://www.w3.org/2002/03owlt/FunctionalProperty/test002"
It should have said:
  xml:base="http://www.w3.org/2002/03owlt/FunctionalProperty/conclusions002"

(Contrast with the third of the tests which mirrors the first)

My intent is that the xml:base declarations are redundant if you download
the tests from their intended URL. The motivation is so that if the test 
is
copied elsewhere, e.g. into an e-mail message; or is downloaded from a
functional equivalent but syntactically identical URI such as one starting
with HTTP, the test is unchanged.

Actually, for the resolution of the relative URI, the typo is not
substantive.
So I will describe that resolution with respect to the uncorrected test.

   rdf:about="premises002#object2"

This is a relative URI, to resolve against the absolute base URI

http://www.w3.org/2002/03owlt/FunctionalProperty/test002

you find the "directory" by looking for / on the right, this is:

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

then you concatenate to get the full URIref

http://www.w3.org/2002/03owlt/FunctionalProperty/premises002#object2



Jeremy
Received on Tuesday, 3 September 2002 11:49:04 GMT

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