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Re: Review Direct Semantics

From: Thomas Schneider <schneidt@cs.man.ac.uk>
Date: Mon, 6 Apr 2009 12:39:49 +0100
Message-Id: <407E0FE2-2EEE-4011-BA64-D831F9CB261E@cs.man.ac.uk>
To: OWL Working Group WG <public-owl-wg@w3.org>
Hi Boris,

thanks for your reply and changes. I have comments on some of them:

On 6 Apr 2009, at 11:30, Boris Motik wrote:
>> -----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
>> * 1 Introduction
>>  - 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.

Your rephrasing does make it a lot clearer, and is more elegant than  
my suggestion.

>> * 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.


>> * 2.3.5 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".

OK, I wasn't aware of this.

>> * 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".

Yes, that's the reason why I wanted to see the term "model w.r.t. D"  
defined in addition to "model" only. Since for interpretations the  
term is "interpretation *for* D", it might not be obvious to the  
reader that "model w.r.t. D" means "model that is an interpretation  
for D".

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

I don't think that adding the sentence "A model of O w.r.t. D is an  
interpretation for D that is a model of O." would complicate  
terminology. It simply gives the reader a point of reference for the  
terminology already used in defining the inference problems.

>> * 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}.)

Thanks, that's better.

> 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.

(1) I agree that the maths will always look ugly.

(2) But I don't think we have to live with the addressed ambiguity. My  
suggestion was actually to replace I with J *globally*, which could  
avoid confusion at least between the capital letter I and the digit 1  
used in super-/subscripts. I'm aware that this change (a) doesn't make  
the maths nicer (which just confirms theorem (1) ;-)), and (b) can  
have far-reaching consequences. But it might make reading easier,  
which I find a justifiable motivation. As for (b), I can offer help  
with the necessary changes.



|  Dr Thomas Schneider                         schneider@cs.man.ac.uk  |
|  School of Computer Science       http://www.cs.man.ac.uk/~schneidt  |
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|  University of Manchester                                            |
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|  Manchester M13 9PL                                      (o~o)       |

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Received on Monday, 6 April 2009 11:40:33 UTC

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