Re: Annotations in Abstract Syntax

From: Sean Bechhofer <seanb@cs.man.ac.uk>
Subject: Annotations in Abstract Syntax
Date: Mon, 19 May 2003 16:09:29 +0100 (GMT Daylight Time)

> Peter -
> 
> The abstract syntax [1] allows one to make annotations about classes,
> but with the transformation rules as defined, I'm not sure how useful
> this is. For example, if we have something like:
> 
>  Class(x partial annotation(rdf:comment "Xs are Ys") y)
> 
> this gets transformed into triples whose subject is the ID of the
> class being defined. So from the above we get:
> 
>  x rdf:type owl:Class
>  x rdfs:subClassOf y
>  x rdfs:comment "Xs are Ys"
> 
> However the way that the transformation is defined means that it's
> impossible to recreate the original intention as the annotation is
> only associated with the classID. For example, if I had another axiom:
> 
>  Class(x partial annotation(rdf[s]:comment "Xs are Ys") y)
> 
>  Class(x complete annotation(rdf[s]:comment "Xs are actually Zs" z)
> 
> then I'd get:
> 
>  x rdf:type owl:Class
>  x rdfs:subClassOf y
>  x rdfs:comment "Xs are Ys"
> 
>  x rdf:type owl:Class
>  x owl:intersectionOf <List with only z in it>
>  x rdfs:comment "Xs are actually Zs"

Correct so far.

> When trying to reverse this transformation I've got no way of knowing
> where the comments should "go".

Yes, I agree that this is not ideal.  However, I don't see any better way
of translating this to triples.

Again, if we could have had our own syntax, then all this could have worked
much better, but the limited organizational power of RDF means that it is
very difficult to build the kind of structure needed to associate
annotations with pieces of syntax.  

Consider, for example

  Class(x partial annotation(rdfs:comment "Xs are Ys") y)
 
  Class(x partial annotation(rdfs:comment "Xs are actually Ys" y)

I don't see any way of keeping the annotations straight here.

> Is this a fair assessment or am I mistaken here, and if I'm not
> mistaken is it something to worry about (I think it might be...)?

Yes, I do worry about this sort of thing occasionally, but I try not to let
it get in the way of doing real work.  :-)

> Cheers,
> 
> 	Sean
> 
> [1] http://www-db.research.bell-labs.com/user/pfps/owl/semantics/

peter

Received on Tuesday, 20 May 2003 05:23:35 UTC