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Re: current version of Feature Synopsis document

From: <herman.ter.horst@philips.com>
Date: Fri, 7 Jun 2002 14:05:20 +0200
To: webont <www-webont-wg@w3.org>
Message-ID: <OF11B44E64.285E4EFD-ONC1256BD1.003CC50E@diamond.philips.com>
In order to facilitate further work on the document of which
Peter provided a new version (6 June 2002) at
I summarize below the points of my previous comments
(at http://lists.w3.org/Archives/Public/www-webont-wg/2002Jun/0008.html)
which are not yet addressed or not yet addressed completely.

--Section 2
The term individual-valued property is an improvement.
However, the ambiguous phrase "Individual IDs" remains.
Replacement of the term individual by resource would
simplify terminology.

There is now a reference to model-theoretic semantics.
This is a meta-remark. I suggest combining all meta remarks
in Section 1 (and/or an appendix), so that Sections 2, 3, 4 are 100% 
devoted to what the document title says: giving a feature synopsis of 
full OWL. At this point in the text there still is a gap in the 
description of the language features and their meaning, which could be 
closed with sentences like:
-Classes denote subsets of the set of all individuals.
-Properties denote sets of pairs of individuals and/or data values.

--Section 3
Two remarks about frames.
Because the language is meant for the Web, it is of interest, also 
on the abstract level, to be able to distribute axioms for a class or 
property into different parts.  I suggest to add this explicitly.
For subclass axioms, meaning is given by intersecting the parts.
For property axioms, this is slightly more subtle.

Second remark: Use the term frame only in historical/meta remarks
(to be moved out of the feature presentation flow). 
Each simplification of terminology reduces the threshold 
between OWL and its potential users.

--Section 3.4
The notion of restriction was considered difficult in DAML+OIL.
I suggest to replace the first, brief, explanatory sentence by the more 
explicit sentence: "Restrictions enable the definition of classes in 
terms of constraints on properties."

--Section 4
I agree with Jeff that the first production seems superfluous.
The problem I noted earlier still seems to exist, with other
production names. It is not just a matter of choosing the right
name, as Jeff suggests.
The first line of the <propertyValue> production implies that a 
<individualFact> always stands for an individual.
But the production for <individualFact> says that a <individualFact> 
stands for one or more assertions about an individual.
What is meant here? Is an individualFact implicitly also an individual 
(reification), or does the individualFact need to be projected to the 
individual about which it is an assertion?
In the latter case, the first line of the <propertyValue> production 
should in my view be omitted, and replaced by the addition of such a 
projection function.

It is desirable to add explanation about how facts about anonymous 
individuals work.

Herman ter Horst
Received on Friday, 7 June 2002 08:08:11 GMT

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