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Re: Conformance was Re: apologies and TEST update

From: Jim Hendler <hendler@cs.umd.edu>
Date: Mon, 6 Jan 2003 07:14:49 -0500
Message-Id: <p05200f03ba3f1ccbf61f@[10.0.1.3]>
To: Jeremy Carroll <jjc@hpl.hp.com>, www-webont-wg@w3.org

jeremy-
  While I very much like the idea of having a way that tools without a 
reasoning capability can be considered OWL compliant in various ways, 
I think I'm generally with Dan in thinking that it is too early for 
us to try to formalize this stuff,

but in case the WG disagrees, let me more specifically comment...


>
>  This section uses the language of [RFC 2117]. (sic)
>
>A language tool without a reasoning capability MAY claim OWL Lite conformance
>if it can:
>
>+ Accept all OWL Lite constructs.

that I can live with

>+ Distinguish RDF/XML documents that conform with OWL Lite from those that do
>not. Specifically, it MUST identify those RDF/XML documents that can be
>formed by applying the mapping from the abstract syntax for OWL Lite as
>defined in [OWL Abstract Syntax and Semantics].

this doesn't make sense to me and I would oppose it. Why should an 
OWL Lite tool think of OWL Full as anything other than an arbitrary 
RDF document?  If I take my tool and feed it something in OWL DL or 
Full, it will likely have some heuristics to notice and reject things 
not in the  sublanguage (i.e. our current tools could recognize that 
owl:union being applied to something is not in Lite) but we treat 
things from OWL Full as if they're RDF.  THat is, if someone says

:foo a owl:class;
   rdfs:comment "This is a owl class";
   dc:creator "hendler";
   :nodeID "37a".

and
  :nodeID a rdfs:property.

then we have put a property on a class (violating class as instance), 
but recognizing which is legal between rdf:comment, dc:creator, and 
:nodeID isn't easy (in fact, I'm not actually sure - does putting an 
rdfs:comment on a owl:class violate class as instance?  What about a 
dc:creator?) - if this was bar:nodeID the checkign gets even more 
ugly...

In short, I don't see how I can be a tool without a "reasoning 
capability" if I have to do reasoning to determine whether a document 
fits the restrictions, and while I think the notion that mapping the 
abstract syntax should be good enough, I'm not convinced it is, 
because of the potential reasoning chains that can cause the problems 
(i.e. X subclass Y subclass Z chains).


>+ Provide support for name separation corresponding to the separation of the
>domain of discourse.

I'm assuming by this you mean that if I try to create something of 
one type, when it's been declared as another, the system should 
produce an error.  If so, I could live with it.  Of course, testing 
it exhaustively will be arbitrarily hard as there are some cases 
(like the ones above) where determining the set of all legal types 
may be hard.  If we mean assuming types are separated, this maintains 
that, then I can live with it.  If it means "can determine if types 
are separated, then this is a subcase of the 2nd restriction, which I 
oppse.

>A language tool without a reasoning capability MAY claim OWL DL conformance If
>it is OWL Lite conformant and it can:
>
>+ Accept all OWL constructs.

ok

>+ Distinguish RDF/XML documents that conform with OWL DL from those that do
>not. Specifically, it MUST identify those RDF/XML documents that can be
>formed by applying the mapping from the abstract syntax for OWL DL.

sam problem as 2 above

>Language tools without a reasoning capability MAY claim OWL Full conformance
>if they are OWL DL conformant and they allow name separation support to be
>switched off. Specifically, the following possibilities SHOULD be supported.
>
>+ Classes, datatypes and properties SHOULD be useable as instance data.
>+ Classes and datatypes SHOULD be useable as properties.
>+ Data valued properties SHOULD be useable as individual valued properties.
>+ Subclasses and subproperties of classes and properties in the RDF, RDFS and
>OWL namespaces SHOULD be allowed.

this one I'm more okay with as it means an OWL Full tool cannot have 
certain restriciton.  Of course, this assumes we've changed the 
previous definition.  If not, I could live with deleting both the OWL 
DL and OWL Lite restrictions, and using this by saying ... Accepts 
both RDF and RDFS graphs as defined in <cites> and the following 
properties SHOULD be supported:

>
>  Reasoning components MAY claim complete OWL DL conformance [or complete OWL
>Lite conformance] if they provide complete reasoning over OWL DL [or OWL
>Lite]. i.e. A conformant complete OWL DL [Lite] reasoner MUST find proofs for
>all OWL DL [Lite] inferences. A conformant complete OWL DL [Lite] reasoner
>MAY find proofs for any OWL Full inference. A system which claims complete
>OWL DL conformance MUST also be OWL DL conformant.A system which claims
>complete OWL Lite conformance MUST also be OWL Lite conformant.

I won't comment since I don't intend to build reasoning components 
per se, and will let those who do decide this (modulo the comments 
above w/respect to conformance)

>
>A document MAY be described as an OWL Lite document if:
>
>+ It does not use any constructs not in OWL Lite.
>+ It corresponds to some document in the abstract syntax for OWL Lite using
>the mapping defined in [OWL Abstract Syntax and Semantics].
>
>A document MAY be described as an OWL DL document if:
>
>+ It does not use any constructs not in OWL DL.
>+ It corresponds to some document in the abstract syntax for OWL DL using the
>mapping defined in [OWL Abstract Syntax and Semantics].

these I actually like - I do think we can define conformant 
documents.  However, there are some wordings that need to be more 
careful - for example, is rdfs:comment "in OWL Lite"?  i.e. OWL Lite 
as defined in...

also, why not for OWL Full?  We could specify this is any document 
that uses RDF and RDFS, whcih would help address the question we're 
often asked as to relation between these...

>
>]]


-- 
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 Monday, 6 January 2003 16:25:03 GMT

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