- From: Jim Hendler <hendler@cs.umd.edu>
- Date: Tue, 21 Jan 2003 08:04:24 -0500
- To: Jeremy Carroll <jjc@hplb.hpl.hp.com>, Guus Schreiber <schreiber@swi.psy.uva.nl>
- Cc: WebOnt WG <www-webont-wg@w3.org>
Jeremy, I really don't agree with most of the detail of the below with respect to the CR criteria you propose (although if we meet them I think we would have the privilege of being the WG with the most complete implementation report in the history of the W3C), but there is one thing I think we need to do first whatever the group decides -- that is, get to Last Call. Let's do what we need to finish our documents and then deal with the issue of our CR/PR dates and needs. -JH At 9:27 +0000 1/21/03, Jeremy Carroll wrote: >Guus: >> >>The owl.wol file defines owl:Class as a subclass of rdfs:Class. >>So this seems redundant to me, or are we not assuming owl.owl is >>always imported? The same holds for the other examples >>(owl:ObjectProperty is a subclass of rdf:Property, etc.). >>Sorry if I misunderstand. >>Guus >> > > > >I think it might be helpful if I explain where I am coming from ... > > > >- the syntax of OWL Lite and OWL DL is defined by these mapping rules > >- the semantics of OWL Lite and OWL DL are defined in terms of the >abstract syntax. > >- there is a lot of free choice in the exact mapping rules used >(syntactic options which do not present semantic difficulties). This >choice should be made motivated by various concerns. > > >The principle goals of a syntax are: >1: connection to the semantics - this is primary, the syntax must >not present unnecessary obstacles to arriving at the meaning of a >document >(we are a bit on a loser starting from RDF/XML but that's another story) > >2: ease of exposition > It must be possible to articulate what the syntactic rules are, >in a way is reasonably clear. > >3: clarity of error messages > A syntax is used in tools like an editor or a syntax checker. > A syntax is also used in any tool that can read OWL Lite and OWL DL. > At least some of these tools need to be able to output correct >and intelligible error messages on ill-formed input. > >4: ease of porting, interoperation with other syntaxes > I see DAML+OIL, RDF and RDFS as the targets here. > > >This suggests the following syntactic concerns as CR exit criteria: > >+ OWL syntax checker: > at least two independently produced syntax checkers that: > - can be run in an OWL Lite or OWL DL mode > - at least one of which, when presented with a document that is > not OWL Lite can give clear and intellegible indications as to > why not. > - at least one of which, when presented with a document that is > not OWL DL can give clear and intelligible indications as > to why not. > - can be run in strict mode, conforming with the exact specification > (i.e. very unhelpful). > >+ OWL editor > at least two independently produced OWL editing environments that: > - can be run in OWL Lite or OWL DL mode > - in OWL Lite/OWL DL mode either prevent the user from creating > non OWL Lite/OWL DL files, or provide some assistance in fixing > syntactic problems related to belonging to the correct > sublanguage. (I personally doubt that a set of emacs macros can > achieve this satisfactorilly) > >+ OWL documents > The construction of enough OWL sample data, > e.g. two moderate sized OWL Lite ontologies, two moderate sized > OWL DL ontologies, two moderate sized OWL Full ontologies > > The porting of at least two moderate sized DAML+OIL ontologies > into OWL. > > The porting of at least two RDFS schemas into OWL Lite; in such > a way that interoperation between RDFS and OWL Lite is shown. > A strong preference that Dublin Core is one of these. > > > > > > >Now, let's get back to the original question. Why do I want the >mapping rule for owl:Class to optionally redundantly specify that >the URIref is also an rdfs:Class? >Answer, if it isn't in the mapping rule then any RDFS schema that >defines or uses an rdfs:Class is not part of OWL DL or OWL Lite. It >is semantically neutral. >The current rule that you must not use rdfs:Class or rdf:Property in >an OWL Lite document seems difficult to explain, and difficult to >justify and to present unnecessary problems in interoperation >between OWL Lite and RDFS. > >Therefore it should change; the change I propose is, as you noticed, >semantically vacuous; which is deliberate. It indicates that there >are no possible semantic problems in agreeing to it. > > >Jeremy -- Professor James Hendler hendler@cs.umd.edu Director, Semantic Web and Agent Technologies 301-405-2696 Maryland Information and Network Dynamics Lab. 301-405-6707 (Fax) Univ of Maryland, College Park, MD 20742 240-731-3822 (Cell) http://www.cs.umd.edu/users/hendler
Received on Tuesday, 21 January 2003 08:08:17 UTC