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RE: Question: disjointness of classes and datatypes

From: Peter Crowther <peter.crowther@networkinference.com>
Date: Thu, 23 Aug 2001 12:05:45 +0100
Message-ID: <B6F03FDBA149CA41B6E9EB8A329EB12D05A689@vault.melandra.net>
To: "'David Allsopp'" <dallsopp@signal.qinetiq.com>, www-rdf-logic@w3.org
> From: David Allsopp [mailto:dallsopp@signal.qinetiq.com]
> However, this disjointness is not expressed in the language
> specification of DAML+OIL 
> (http://www.daml.org/2001/03/daml+oil.daml) as
> far as I can see.
> Is there a reason for this?

The language spec specifies the syntax of DAML, not its semantics.  In a
couple of places you need to be able to specify that a class or a datatype
could occur, so it's difficult to enforce the disjointness in the syntax.

If you want to find the formal basis, you'll need to look at one of the
semantics docs: axiomatic or model-theoretic.  For example, check out the
model-theoretic semantics at
http://www.daml.org/2001/03/model-theoretic-semantics.html.  The key appears
to be in the preliminary mappings to the two domains AD (abstract) and DD
(datatype) plus the definitions of IC and IO.

> How should a resource that claims to be an
> instance or subclass of both daml:Class and daml:Datatype be handled -
> the reference description says this is illegal but the language spec
> doesn't.

The resource is incoherent, I think.

		- Peter
Received on Thursday, 23 August 2001 07:06:06 UTC

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