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Re: wording on Unknown returns in Conformance

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Wed, 24 Sep 2008 12:37:49 -0400
Message-ID: <29af5e2d0809240937k6c4bd50ai32f67090342fa96e@mail.gmail.com>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: public-owl-wg@w3.org
I was thinking about something along the lines of (specific words could
change). My changes in italics. There's probably a better word than "minimally
conforming" but I can't think of one right now.

An minimally conforming OWL 2 Full entailment checker is an OWL 2 entailment
checker that takes RDF documents as input, and uses the RDF-Based Semantics
[OWL 2 RDF-Based Semantics]. It must return True only when O1 entails O2,
and it must return False only when O1 does not entail O2. It may return
Unknown if it is not capable of determining whether an entailment holds or
not.
A complete OWL 2 Full entailment checker is a minimally conforming OWL 2
Full entailment checker that should not return unknown.

Then, in section 2.2.1

It *must* provide a means to determine the semantics it uses (either the
Model-Theoretic Semantics [OWL 2
Semantics<http://www.w3.org/2007/OWL/wiki/Test#ref-owl-2-semantics>]
or the RDF-Based Semantics [OWL 2 RDF-Based
Semantics<http://www.w3.org/2007/OWL/wiki/Test#ref-owl-2-rdf-semantics>]),
and whether it is minimally conformant or complete; for example, in its
supporting documentation.

Similarly for other profiles.

I would add a note that at the time of publication it isn't known whether
complete conformance for OWL Full is possible.

-Alan

On Wed, Sep 24, 2008 at 12:26 PM, Peter F. Patel-Schneider <
pfps@research.bell-labs.com> wrote:
> Huh?  What is this, and how would it be done.
>
> peter
>
> From: "Alan Ruttenberg" <alanruttenberg@gmail.com>
> Subject: Re: wording on Unknown returns in Conformance
> Date: Wed, 24 Sep 2008 12:17:07 -0400
>
>> I had thought that it might be worth distinguishing distinct levels of
>> conformance - complete versus incomplete. Do you think that would be a
>> good idea? It bothers me a bit that conformance as specified for OWL
>> Full, as stated now, is not known to be possible.
>> -Alan
>>
>>
>> On Wed, Sep 24, 2008 at 10:04 AM, Peter F. Patel-Schneider
>> <pfps@research.bell-labs.com> wrote:
>> >
>> > There have been some comments on the "should not" wording in the
>> > conformance part of the Test and Conformance document.
>> >
>> > The current wording includes
>> >
>> >  An OWL 2 Full entailment checker is an OWL 2 entailment checker that
>> >  takes RDF documents as input, and uses the RDF-Based Semantics [OWL 2
>> >  RDF-Based Semantics]. It MUST return True only when O1 entails O2, and
>> >  it MUST return False only when O1 does not entail O2. It SHOULD NOT
>> >  return Unknown.
>> >
>> > Without the last sentence, a trivial checker, i.e., one that always
>> > returned "Unknown" would be just as good an OWL 2 Full entailment
>> > checker as one that tried hard.
>> >
>> > Even worse, if the last sentence was removed from
>> >
>> >  An OWL 2 DL entailment checker is an OWL 2 entailment checker that
>> >  takes OWL 2 DL ontology documents as input, and uses the Model
>> >  Theoretic Semantics [OWL 2 Semantics]. It MUST return True only when
>> >  O1 entails O2, and it MUST return False only when O1 does not entail
>> >  O2. It SHOULD NOT return Unknown.
>> >
>> > then a trivial checker would be just as good as a complete reasoner for
>> > OWL 2 DL.
>> >
>> >
>> > I thus feel that there needs to be some wording in the conformance
>> > document to show that trivial checkers, or unnecessarily incomplete
>> > checkers, are not as good as ones that return "Unknown" in fewer cases.
>> >
>> > Remember that "should not" is not the same as "must not".  A checker
>> > could return "Unknown" if
>> > 1/ it ran out of resources (memory, time, etc.); or
>> > 2/ it is an incomplete reasoner (for OWL 2 Full, for example, or even
>> >   for OWL 2 DL).
>> > The above reasons (or others) could be used by entailment checkers to
>> > provide a justification for "Unknown" answers.  I feel, however, that
>> > this is outside the scope of the specification.
>> >
>> > Perhaps it would be useful to add some wording on justifying "Unknown"
>> > to the document, but I think that most of this is implied by the use of
>> > "should not".
>> >
>> > peter
>> >
>> >
>
Received on Wednesday, 24 September 2008 16:38:28 UTC

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