Re: A proposal for ISSUE-104 (built-in vocabulary)


I just want to flag an issue that may come up later in comments: on 
practical sense your proposal has a downside for RDF users. Indeed, the 
two major serializations formats, ie, RDF/XML and Turtle, have syntactic 
shorthands for RDF Lists, and these would not be valid for the owl 
version of those. And coding first/rest pairs explicitly is not pretty.

There may not be a way out due to the data/object property issue, but we 
have to know about this downside I guess...


Boris Motik wrote:
> Hello,
> The discussion around ISSUE-104 (reserved vocabulary) seemed to show that lists and reification are the main, if not the only part
> of the reserved vocabulary that might be useful in OWL 2 DL. (If we feel that it is necessary, we may verify this by sending an
> e-mail to owl-dev once we have fleshed out our proposal. I personally don't think we need to do this, given my experience how the
> built-in vocabulary has been used in OWL 1.)
> Based on the assumption that we more or less agree on the above observation, I would like to put forward a proposal for resolving
> this issue. Before I do so, let me first explain why the obvious way of resolving the problem does not work.
> 1. A slight problem with exempting rdf:List from the reserved vocabulary
> ------------------------------------------------------------------------
> For a property to be used in any OWL 2 DL axiom, the property must be declared as either an object or a data property. Now this
> causes a slight problem for rdf:List: we would make a hard-and-fast choice about how to treat rdf:first. Thus, we would have to
> decide whether rdf:first is an object or a data property, which would essentially restrict the usage of lists in OWL 2 DL in a nasty
> way.
> 2. A possible way forward
> -------------------------
> To allow for lists, we would introduce four new vocabulary elements in OWL 2:
> - owl:List
> - owl:firstLiteral
> - owl:firstIndividual
> - owl:rest
> To ensure semantic compatibility with OWL Full, we would make owl:List a subclass of rdf:List, owl:firstLiteral and
> owl:firstIndividual a subproperty of rdf:first, and owl:rest a subproperty of rdf:rest.
> We would extend the structural spec to provide built-in declarations for these properties (in the obvious way). We would also add a
> subsection to the structural spec and to the primer about how these are to be used in ontologies.
> We would leave the rest of the built-in vocabulary in OWL 2 DL as it currently is.
> Note that this does not address the reification vocabulary. Reification is considered bad in RDF anyway, and it would introduce
> similar problems in OWL 2 DL; therefore, it seems to me that disallowing it in OWL 2 DL is not a big deal.
> Let me know how you feel about this.
> Regards,
>  Boris


Ivan Herman, W3C Semantic Web Activity Lead
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Received on Wednesday, 11 June 2008 13:12:47 UTC