Re: Semantics, in particular DAML+OIL semantics

On August 12, R.V.Guha writes:
> 
> Ian, thank for posting these to rdf-logic. It would be good to have a 
> discussion on the issue of different approaches to providing a semantics 
> for the languages of the semantic web.
> 
> I agree with you that for the purpose of providing a semantics for any 
> one particular language, a "native" model theory, i.e., one that maps 
> sets of expressions in that language to satisfying interpretations, is 
> best in terms of perspicuity and pedagogy. So, I agree that it is 
> important that RDF, OWL, ... be given native model theories.
> 
> I would however argue that in the context of the Semantic Web, we are 
> dealing with a situation that is quite different from when we are 
> developing a single, standalone language. We are developing a set of 
> languages, that are supposed to work together, i.e., wffs on the SW may 
> include constructs from multiple of these languages. More so, these 
> languages are expected to be layered on top of each other. Now, one can 
> argue, as some have, that this charter is ill-concieved, but for the 
> purpose of this email, I will assume that as a given. Further, I am also 
> not going to get into a discussion of whether RDF/OWL should include 
> certain features. That is the topic of another email.
> 
> The problem, in this context, with relying solely on model theories, is 
> that this does not give us a tool for providing a semantics for 
> expressions that mix constructs from  different languages. That is a 
> rather severe limitation of relying solely on model theories.  Axiomatic 
> approaches on the other hand, by mapping everything into a common 
> language, do enable us to provide a semantics for such "mixed expressions".
> 
> I am not advocating that we abandon model theoretic approaches in favour 
> of the other approach. I would like to see both. Which of course brings 
> us to the issue of making sure that both are saying the same thing. 
> Fortunately, since the whole semantics game grounds out in 
> interpretations, I believe we can have a formal model of what it means 
> for these two approaches to say the same thing. Pat Hayes and I have 
> taken a stab at this in our Lbase document.
> 
> I look forward to your reactions.

I don't have much to add to the comments made by Enrico and Peter.

From my point of view, I am happy for people to study the semantics of
(combinations of) various web languages using a variety of approaches
including both MT and translation/axiomatisation.

Unfortunately, I don't see how such studies can resolve the practical
problems associated with layering OWL on top of RDF, e.g., those
caused by RDF's ability to talk about its own syntax, and the
inheritance of this ability by wore expressive languages layered on
top of it.

Regards, Ian


> 
> thank you
> 
> Guha

Received on Wednesday, 14 August 2002 06:40:40 UTC