- From: Jim Hendler <hendler@cs.umd.edu>
- Date: Thu, 15 May 2003 19:09:05 -0400
- To: webont <www-webont-wg@w3.org>
Guus and I have been sorting through the comments looking for those where the WG may have to be in the critical path. We've identified the ones below as most likely to either raise or reopen an issue. We will be sending individual messages asking various editors or other WG members to "volunteer" to write responses (to submit back to the WG - not to the public-list without an okay first) - the below is to let everyone know what the list is and to solicit comments on those you feel strongly about. There are many other comments not on this list, and we hope the editors will keep working on those in the way you've been doing so far -- we've made a dent, but there's a long way to go (*sigh*) - some of these have already been assigned -- in that case they say ASSIGNED: and to whom... ======================= General LC comments overview 13 May ---------- RDFCore: Comments on OWL Reference - owl:class not needed http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0004.html #owlref-rdfcore-owl-class-denotation It has been suggested to RDFCore that owl:Class is not needed. RDFCore requests the creation of test cases to clearly illustrate the differences between owl:Class and rdfs:Class. ISSUE OPENED: NOT YET ASSIGNED (action Hayes) ------------ RDFCore: Comments on OWL Reference - more readable RDF mapping http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0053.html #owlref-rdfcore-relationship-to-RDF RDFCore requests that the specifications be amended to include a description of necessary conditions for a RDF document to be in OWL DL and OWL Lite. This description should be as accurate as possible consistent with a goal of it being comprehensible to a majority of the community. ------------- RDFCore: NP completeness of owl/RDF mapping http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0052.html #owlsas-rdfcore-np-complete RDFCore notes the a consequence of the rules for owl:equivalentClass is that distinguishing OWL DL from OWL Full has complexity NP complete and suggests WEBONT investigate whether this complexity can be reduced. ASSIGNED: PETER P-S ------------- RDFCore: B-node issues http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0052.html #owlsas-rdfcore-bnodes-restrictions [..] we request, that in Owl DL and Owl lite: a) that a b-node representing an individual may be the object of more than one triple b) that cycles of b-nodes representing individuals be allowed. --------------- Varant: OWL and Published Subjects http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0013.html [opportunities, no real issues/comments] ASSIGNED HENDLER -------------- McGregor: Non-global Keys http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0019.html OWL ought to include a syntax for defining non-global keys. For example, suppose the classes Employee and EmployeeHistory both share the attribute hasSSN. One would like to be able to assert that 'hasSSN' is a key for instances of Employee, but not for instances of EmpoyeeHistory. InverseFunctionalProperty does not permit this. ASSIGNED HENDLER/CONNOLLY -------- Reynolds: OWL comment - language subsets and complexity http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0045.html We wish to register a comment on the implementation complexity of the selected subsets of OWL - Lite and DL - based on our implementation experience with Jena. One means to simplify OWL/Lite would be to restrict class definitions to only be "partial". Our concern is that this would go too far - there is value in having complete definitions in order to support classification of individuals based on their properties. We wonder if a constraint of the form "each classId may only participate in a single axiom of the form Class(classID complete ...)" would remove this source of complexity. We ask those with greater knowledge of this field to explore whether an approach along these lines would enable OWL/Lite to better live up to its name. ASSIGNED HENDLER ------------- Merry: OWL Comment: have long CR period for OWL, or move owl:oneOf, owl: have Value to OWL Full http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0046.html An alternative, would be to redefine OWL DL downwards, excluding owl:oneOf and owl:hasValue, which would then be subject to the health warnings of OWL Full - i.e. use of these constructs means that your ontology is likely to be outside the limits of practical reasoning. Such a redefinition of OWL DL, could sensibly accompany a redefinition of OWL Lite to exclude complete class definitions. ASSIGNED HENDLER ----------- OWL comment - blank nodes in OWL DL http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0048.html It is not clear why OWL DL has not permitted, for example, an unnamed individual to be the object of more than one triple, or an unnamed individual to be the object of a triple of which it is the subject. Please either relax this constraint or offer a rationale. ----------------- Beckett: OWL S&AS comment - owl:imports http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0056.html See also Use case raised by Golbeck http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0068.html A semantic import mechanism for the RDF-based languages looks potentially useful and in considering if and how to implement it, there are some problems. Firstly it seems that owl:imports potentially will import the entire semantic web of OWL Ontologies. Have you considered the security and denial-of-service implications of this mechanism? Secondly, is not clear at what stage that this (Imports Closure http://www.w3.org/TR/2003/WD-owl-semantics-20030331/rdfs.html#5.3 ) should be done. In an example where you have some RDF/XML that will map to RDF triples describing an OWL ontology, what are the steps that you expect to happen? use case: NCI cancer ontology - wants to break into smaller pieces, but import rebuilds the whole thing. --------------------- Beckett: OWL Reference comment - RDF Schema for OWL http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0082.html > Appendix B is not normative. So that means there is no normative description in machine readable form of the OWL vocabulary, in OWL, as written down in RDF/XML. Is all the OWL vocabulary expected to be built-in application knowledge? What is the purpose of this section? It would benefit from an explanation. ASSIGNED GUUS S ---------------------- Beckett: OWL S&AS: Translation to RDF Graphs http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0059.html [only S&AS?!] This transformation table gives the mapping from OWL's abstract syntax to RDF triples which means that if you have an OWL ontology in the abstract syntax you can write it in OWL's transfer syntax - RDF triples. It is however more difficult to see how to go from RDF triples to OWL's abstract syntax. As a semantic web technology, OWL builds on RDF triples (and RDF on XML for syntax, URIs etc.) and this form of presentation makes it harder to see how to start with RDF and gain from OWL vocabulary. ---------------------- wwmm: AllDisjoint http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0076.html see also: support from Vatant and McCullough Alford: AllSame http://lists.w3.org/Archives/Public/public-webont-comments/ 2003May/0070.html see also: Use case raised by biologists (reported by Hendler) http://lists.w3.org/Archives/Public/www-webont-wg/2003May/ 0206.html Since there is an owl:AllDifferent, why is there not an owl:AllDisjoint? It means that all class disjoint with each other. use case: biological taxonoma with 100s of disjoint classes at some levels. Note this is NOT a disjoint union, just a large set of disjoints. ASSIGNED HENDLER ------------- Laskey: General issues http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0071.html I have been thinking about the OWL Last Call drafts for some time and I have been troubled by a general feel of unease. While the use cases provide a broad range of interesting and useful scenarios, my general feeling is that OWL as presented will not be an effective means to accomplish these ends. I would be more comfortable if I could point to specific shortcomings that I could suggest be corrected (such as the n^2 problem with disjoint classes - why not have a mutuallyDisjoint construct that is applicable to a list of arguments?), but my issues go deeper than this. In discussions with others (including some outside SAIC), I have encountered a pervasive feeling that OWL might be interesting but will not have significant impact on real problems. Any examples in the drafts that go beyond the trivial are complicated and tedious, and it is unlikely that anyone beyond a diehard would have the motivation to do any significant ontology capture in this format. ASSIGNED HENDLER
Received on Thursday, 15 May 2003 19:09:10 UTC