- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Fri, 07 Jun 2002 08:56:41 -0400
- To: herman.ter.horst@philips.com
- Cc: www-webont-wg@w3.org
From: herman.ter.horst@philips.com Subject: Re: current version of Feature Synopsis document Date: Fri, 7 Jun 2002 14:05:20 +0200 > In order to facilitate further work on the document of which > Peter provided a new version (6 June 2002) at > http://www-db.research.bell-labs.com/user/pfps/owl/owl.html, > 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. I resist this change. The term ``resource'' is, I feel, not appropriate at the level of this document. > 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. I feel that this would unduely complicate the document. Why not leave the (small) description of the meaning of the features in-line? > 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. These are in the last paragraph of section 2. > --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. I take it that you want wording to indicate the effect of multiple axioms for the same name. I have added a paragraph on this just before 3.1. > 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. Why should there not be an allusion to frames? This way of organizing the axioms was chosen partly for its similarity to frames, so I see only utility in mentioning the relationship. > --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." I view this sentence as more misleading than what is currently there. I have, however, modified the current text. > --Section 4 > I agree with Jeff that the first production seems superfluous. It is not. A fact is either an individualFact, a SameIndividual, or a DifferentIndividual. However, inside a propertyValue, only an individualFact is allowed, fixing a bug that you pointed out. > 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. Which problem? I fixed the problem that existed before. > The first line of the <propertyValue> production implies that a > <individualFact> always stands for an individual. Yes, an individualFact is an Individual, i.e., an RDF description element with a slighly different syntax. > But the production for <individualFact> says that a <individualFact> > stands for one or more assertions about an individual. Yes, an individualFact can include one or more propertyValues, each of which provides information about the individual. > What is meant here? Very close to what is meant in RDF. > Is an individualFact implicitly also an individual (reification), NO REIFICATION!!! NO REIFICATION!!! NO REIFICATION!!! NO REIFICATION!!! > or does the individualFact need to be projected to the > individual about which it is an assertion? I don't understand this. > 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. I don't understand how this does anything besides introduce problems. > It is desirable to add explanation about how facts about anonymous > individuals work. You mean besides referring to RDF? I'm not particularly willing to include enough to make a significant difference in comprehensibility. > Herman ter Horst peter
Received on Friday, 7 June 2002 08:56:57 UTC