Re: Classes and predicates as first class objects

On August 14, R.V.Guha writes:
> 
> 
>  Much of the debate around layering of OWL on top of RDF and RDFs boils 
> down to whether the Semantic Web should treat classes and arc labels as 
> first class objects, about which arbitrary new kinds of statements can 
> be made.
> 
> This is an important architectural choice which has to take into account 
> results from systems that have been built. Looking at what was learnt 
> from such systems would probably be productive ...
> 
>  RDF, which has been largely influenced by the experimental "scruffy" 
> side of AI has gone the route of many experimental AI systems (starting 
> from KRL, RLL, .... CycL) and incorporated these as first class objects. 
> In my experience, and the experience of the builders of these systems, 
> this has been a useful feature. Description Logics, which come from the 
> more "neat" side of AI chose not to allow this ...
> 
> Clearly, not allowing this feature buys description logics something. 
> Ian, maybe you could explain exactly what this is and how it has been 
> found useful in large DL systems that have been built?

Work on DLs has resulted in the development of a family of logical
languages with precisely defined semantics and well understood
computational properties. They are (almost invariably) decidable
subsets of FOL and are closely related to propositional modal and
dynamic logics.  For many of these languages, provably sound and
complete decision procedures have been devised. Several DL systems
have been based on optimised implementations of these algorithms, thus
providing users with reasoning services that are both reliable and
efficient. These systems are being used in a wide range of
applications, e.g., in medical-informatics, bio-informatics, chemical
engineering and geographical information systems.

Ian

> 
> thanks,
> 
> guha
> 
> 
> 
>  

Received on Thursday, 15 August 2002 16:45:18 UTC