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RE: Review Direct Semantics

From: Boris Motik <boris.motik@comlab.ox.ac.uk>
Date: Mon, 6 Apr 2009 11:30:06 +0100
To: "'Thomas Schneider'" <schneidt@cs.man.ac.uk>, "'OWL Working Group WG'" <public-owl-wg@w3.org>
Message-ID: <E8A3D2095A9A4F379ECB582E2CC49D7B@wolf>
Hello Thomas,

Thanks a lot for your comments. Please find my answers inline.



> -----Original Message-----
> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On
> Behalf Of Thomas Schneider
> Sent: 05 April 2009 15:40
> To: OWL Working Group WG
> Subject: Review Direct Semantics
> Hi Boris, Peter and Bernardo,
> please find below my comments.
> Cheers
> Thomas
> ============================================================
> Review for "OWL 2 Web Ontology Language -- Direct Semantics"
> ============================================================
> revision 21904
> http://www.w3.org/2007/OWL/wiki/index.php?title=Semantics&oldid=21904
> Summary
> -------
> I find this document clear, precise and technically correct, and have
> only a few minor comments.
> Specific comments
> -----------------
> * 1 Introduction
>   - 2nd sentence: This is much clearer than before. However, I have
>     stumbled over "is compatible with", which is quite lax and not a
>     standard term in this setting.  It is of course explained in the
>     following sentences, but why not say "extends" in the first place?


>   - 4th paragraph, 1st sentence: It might be clearer to repeat "of",
>     i.e., "annotations of ontologies, *of* anonymous individuals, *of*
>     axioms, and *of* other annotations". Otherwise an unexperienced
>     reader might misunderstand the meaning of the sentence as "OWL 2
>     allows for annotations of ontologies, *for* anonymous individuals,
>     *for* ...".

I'm not sure whether repeating *of* would be grammatically correct. I have,
however, rephrased the sentence to make things clearer.

> * 2.1 Vocabulary
>   - Here and in the following subsections, I'm still not happy with
>     "(C)^C" and "(DT)^{DT}". I know we have discussed quite a few
>     alternatives and ruled them out for several reasons. But still I'm
>     sure that "(C)^C" etc. will confuse non-experts, although I don't
>     have a suggestion for a new solution.

Unfortunately, we are dealing here with HTML and not LaTeX, and there are just
limits to what one can achieve in such an environment.

> * 2.2.2 Data Ranges
>   - The remark that data ranges can be n-ary doesn't make it clear
>     that this document (following the Specification) only considers
>     the unary case. For a moment, I was expecting to see the
>     interpretation of an "atomic" n-ary data range. The wording in the
>     Specification [ http://www.w3.org/2007/OWL/wiki/Syntax#Data_Ranges
>     , 4th sentence ] makes this clearer than the wording in the Direct
>     Semantics; perhaps it should be copied.

I've rephrased the paragraph to make this clearer.

> * 2.3 Satisfaction in an Interpretation
>   - What is the purpose of the last occurrence of "the axiom" in the
>     1st sentence? If "axiom" has to occur three times in this
>     sentence, it might be given a name. I remember that we had issues
>     with greek letters not being rendered correctly, but why not call
>     the axiom A, Ax, or ax?

I've rephrased the paragraph.

> * 2.3.5 Keys
>   - Why not replace "keys" (in heading, sentence and table caption)
>     with "key axioms"? This would be consistent with the 2nd sentence
>     of 2.3.

I've followed the heading structure for the Syntax document. Some people
expressed the desire to call these just "Keys", rather than "Key Axioms".

> * 2.5 Inference Problems
>   - Now that all inference problems are defined w.r.t. a datatype D,
>     we have the problem that the term "model" is not defined w.r.t. D.

A model is an interpretation, so it is clearly defined w.r.t. D. In all
definitions of the inference problems, we already say things such as "a model
w.r.t. D exists".

I'm not sure whether being more explicit would be desirable: if would just
complicate the terminology without any substantial additional information.

>   - 3rd last sentence: I've added a reference to the definition of a
>     simple OPE to the word "simple".

Great -- thaks!
> * Throughout
>   - When viewing the document with sans-serif fonts, the capital
>     letter I and the digit 1 can hardly be distinguished. This
>     complicates reading some of the expressions used in the document,
>     e.g. those in the 3rd and 4th line of Table 4. In 2.4, you even
>     use I_1, which contains \Delta_I and \cdot^{I_1}, but all
>     subscripts read like the capital I.
>     I remember that Boris has mentioned this problem in the last
>     discussion, but I don't think we've fully discussed the
>     alternatives here. I'm aware that possible changes can be
>     far-reaching and therefore require a lot of work, but still I'd
>     prefer to avoid confusion whenever possible. So how about using
>     the capital "J" instead of "I"?

I've changed I into J in the definition of models. (I believe the latter was the
only place where we used {I_1}.)

The changed text looks again quiet ugly, but there is nothing I can do here:
HTML is just completely inadequate for typesetting mathematics and we will just
have to live with this ugliness.

> +----------------------------------------------------------------------+
> |  Dr Thomas Schneider                         schneider@cs.man.ac.uk  |
> |  School of Computer Science       http://www.cs.man.ac.uk/~schneidt  |
> |  Kilburn Building, Room 2.114                 phone +44 161 2756136  |
> |  University of Manchester                                            |
> |  Oxford Road                                             _///_       |
> |  Manchester M13 9PL                                      (o~o)       |
> +-----------------------------------------------------oOOO--(_)--OOOo--+
> Kentucky (adj.)
>   Fitting exactly and satisfyingly.
>   The cardboard box that slides neatly into a small space in a garage,
>   or the last book which precisely fills a bookshelf, is said to fit
>   'real nice and kentucky'.
>                   Douglas Adams, John Lloyd: The Deeper Meaning of Liff
Received on Monday, 6 April 2009 10:31:18 GMT

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