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Re: WOWG: first language proposal

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Wed, 27 Mar 2002 17:43:04 -0500
Message-ID: <3CA24AF8.6328D3EF@cse.lehigh.edu>
To: Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>
CC: www-webont-wg@w3.org
Frank et al.,

I've been meaning to write regarding your language proposal, and now is
the first chance I've had to respond. I'd like to thank you for your
work on this, I think it's heading in the right direction. Now on to my
comments...

First, I'd like to suggest that we attempt to maintain the frame-nature
of the language for properties as well (kind of like facets). For
example, we could have the productions:

<definition> ::= Property ( <propertyId> ,<facet>* )
<facet> ::= <domain> | <range> | <supersprops> | Transitive |
SingleValued | UniquelyIdentifying 
<domain> ::= domain( <classId> )
<range> ::= range( <classId> | <dataTypeRange> )
<superprops> := supers( <classId>*)
etc.

I'd even like to see this idea carried over into the non-frame portion
of the language. What do you think?

Second, I think we should include some kind of syntax to indicate that a
specific set of definition make up an ontology. Perhaps include:

<ontology> ::= Ontology ( <definition>*)

This can also serve as a place holder for us to later attach ontology
metadata and versioning information.

Third, what are you thoughts on using AND, OR, and NOT instead of
intersectionOf, unionOf, and complementOf (as is done in OIL)? I think
these might be more intuitive, and would certainly be easier for people
to type.

Finally, an important issue will be finding a way to map your abstract
syntax into XML/RDF and still preserve its simplicity. I believe that in
order to get a good, intuitive syntax, we'll have to seriously consider
dropping the idea of using triples to represent the language, i.e., do
not layer on top of RDF Schema (but this is a point I've already raised
in another thread).

Jeff


Frank van Harmelen wrote:
> 
> As per our action item from March 7, we have prepared a first language
> proposal, for discussion in this weeks teleconf, and as the basis for further
> work by the language focus group.
> 
> At http://www.cs.vu.nl/~frankh/spool/OWL-first-proposal/
> you will find three documents:
> 
> - A short motivation of our design and choices (2pgs)
> - An annotated example to give you the flavour (walkthrough) (5pgs)
> - The language definition as a simple grammar (5pgs)
> 
> We suggest you read the documents in this order.
> 
> EXECUTIVE SUMMARY:
> 
> Our proposal for the OWL Knowledge Base Language comes in two parts:
> 
> 1. The first ("light") part is loosely based on the frame idiom found in the
> frame-style systems that have been used in AI for decades. This idiom has been
> extended with commonly found ontology modelling idioms and a number of
> features that are important in the Web context.
> This "light" version will provide a lower entry threshold to the language,
> while still providing much of the required expressiveness.
> 
> 2. The second ("full") part is very close DAML+OIL.
> 
> Peter Patel-Schneider,
> Ian Horrocks
> Frank van Harmelen.
>     ----
Received on Wednesday, 27 March 2002 17:43:08 GMT

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