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Re: TEST: Functional and InverseFunctional tests for approval

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Sun, 1 Sep 2002 08:01:44 +0200
To: <www-webont-wg@w3.org>
Message-ID: <MABBLGKMPIJFCKFGDBEPIECGCBAA.jjc@hpl.hp.com>


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 Sunday, 1 September 2002 01:56:32 GMT

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