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Re: [OEP] Classes as Values - A detailed review

From: Natasha Noy <noy@smi.stanford.edu>
Date: Fri, 4 Mar 2005 11:55:59 -0800
Message-Id: <f09b55eed021631d5061aa7569c8a6e2@smi.stanford.edu>
Cc: public-swbp-wg@w3.org
To: Christopher Welty <welty@us.ibm.com>

Chris, Mike,

I think we are close to done ;)

> THis reflects agreement between Mike and me (except where noted).   A 
> version with these changes is attached for you to merge with the 
> official editors draft:

ok, I have the lock now.

>
> Natasha Noy <noy@smi.stanford.edu> wrote on 03/04/2005 12:15:39 AM:
>  > [New abstract] "This document addresses the issue of using classes
>  > as property values in OWL. It is often convenient to put a class 
> (e.g.,
>  > Lion) as a property value (e.g., topic or book subject) when 
> building an
>  > ontology. While OWL Full and RDF Schema do not put any restriction 
> on
>  > using classes as property values, OWL DL and OWL Lite do not 
> generally
>  > allow this use."
>  >
>  > Fine up to here. Then you removed:
>  > "In OWL DL and OWL Lite, most properties cannot have classes as 
> their
>  > values. "
>  >
>  > Any particular reason you removed this sentence? This qualification 
> is
>  > important, otherwise the preceding statement is misleading: you CAN 
> use
>  > classes as valued in OWL DL, but only for a limited, pre-defined 
> set of
>  > properties (such as rdf:type)
>
> Because the previous sentence says the same thing ("OWL DL and OWL 
> Lite do not generally allow this use.").
>
> OK?

How about we keep the other sentence then, instead of this one -- I 
think it's a bit more clear. Thus the abstract will read:
"While OWL Full and RDF Schema do not put any restriction on using 
classes as property values, in OWL DL and OWL Lite, most properties 
cannot have classes as their values"

ok?

> > [New abstract] "We present various use cases to motivate the need for
>  > representing classes as values."
>  >
>  > I don't think the document does this, nor should it.
>
> Neither of us feel that strongly about having this in the abstract, 
> however we can't figure out why you think the document doesn't do 
> this.  It presents one use case in detail, under the section titled 
> "USE CASE", which is then addressed in all the examples, and in 
> addition there is a section "Other use case scenarios" which mentions 
> other possible use cases, all in the context of motivating why you are 
> doing this.
>
> If you agree, maybe a slight re-wording would be acceptable, but if 
> this will generate prolonged debate it's not worth it and you can 
> remove it.

Hmm... I still feel that the note doesn't try to motivate the use of 
classes as values. In fact, it almost does the opposite: it shows how 
you can represent the same (or very similar) information _without_ 
using classes as values.

>  > >I added a paragraph on issues and considerations.
>  > >  
>  > >
>  > I am still uncomfortable with having this paragraph there. First, I
>  > think it is more than an editorial change and has more of a feel of
>  > value judgment than the rest of the document. Also adds new
>  > information/opinions. Some examples:
>  >
>  > "If inferencing is going to feature in a big way, this may require 
> the
>  > use of OWL-Lite or OWL-DL"
>  > This is just not true: you can do inferencing in OWL Full, it will 
> be
>  > different type of inferencining. I guess what you wanted to say was 
> "If
>  > automatic classification is required" or "If the use of a DL 
> reasoner is
>  > required" or something like that.
>  >
>  > "Is the approach natural, succinct and easy to understand or is it
>  > technically complex"
>  > The problem is that this is also a value judgment. To me, approach 
> 4 is
>  > technically complex, to Alan Rector, nothing could be more natural. 
> Note
>  > that consideration points talk about "Some may consider it to 
> be..." It
>  > really is subjective.
>  >
>  > Also, technical complexity does not necessarily imply difficulty in
>  > maintenance. The approaches that replicate information require
>  > additional maintenance, but they may still be fairly simple (at 
> least
>  > for some).
>  >
>  > "Does the approach entail changing the semantic interpretation of an
>  > ontology that is being reused"
>  > What if you are reusing your own ontology that no one else uses?
>  >
>  > You see where I am going here. For each issue--possible implication 
> pair
>  > that you have in that paragraph, the implication part is easily
>  > controversial. We can keep arguing these points, but it's exactly
>  > because they are not that objective.
>  >
>  > Second, I think this paragraph is not terribly useful at the 
> beginning
>  > of the document anyway: it probably won't make much sense to 
> someone who
>  > hasn't read the document yet. Something like that would be more
>  > appropriate in the summary, but that still doesn't allay my first 
> concern.
>  >
>  > So, Chris is the TF chair, so he can decide whether this indeed 
> amounts
>  > to more than an editorial change. If he thinks it can still be
>  > classified as an editorial change, and you feel strongly about 
> including
>  > it, I am not going to argue and will include it. The issues I 
> mentioned
>  > above will still need to be ironed out -- should be possible.
>
> Mike recognizes your points are valid and still thinks there would be 
> value to adding a section like this. However, he reluctantly agrees to 
> skip this.  

Thanks, Mike, for being flexible on this -- I appreciate it. Note that 
all of this would have been different if we were writing a paper on 
this rather than a W3C note -- then value judgments are appropriate and 
having a section like this is, indeed, valuable. It's valuable for the 
note, too, but at this pint, it would take too much time to build a 
"non-judgmental" consensus, and I am not even sure it is possible. I 
just want to make clear that I don't disagree on this point in general, 
but just for the purposes of this note.

>  > >I did not yet get to a conclusion section.
>  > >  
>  > >
>  >
>  > Let me know what your timing is on that and if you still plan to do 
> it.
>  > Also let me know when you want me to "own" the document. I won't 
> touch
>  > it until you tell me it's ok to do so.
>
> We decided to drop the conclusion.  I do not think it would be 
> "editorial" and I am not convinced it would add any value anyway.

I agree.

>
> Mike had another point that I agreed with - it is easy to miss the 
> sentence that makes clear that this document is not intended to be 
> construed as a statement of how to represent subjects on the semantic 
> web, rather it focuses on ways to represent classes as values.  To 
> address this, in the "other use cases" section I added a little more 
> description of a possible medical classes-as-values use case that 
> specifically mentions another possible property name, moved the 
> statement about this note to a new paragraph, and emboldened the 
> statement.

Yes, I completely agree. Your message arrived just in time to save me a 
whole lot of typing in reply to Mike's message on this :) I think 
expanding the "Other use cases" section is the most appropriate way to 
address this issue. Thanks for doing this.

I'll try to put everything together today, go through it and try to 
weed out typos, etc. and have a new draft later in the day.

Mike, Chris, thanks again for all the help with the documents and 
comments. What an exercise in consensus building :)

Natasha
Received on Friday, 4 March 2005 19:56:04 GMT

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