- From: Dan Brickley <danbri@w3.org>
- Date: Thu, 20 May 2004 10:44:26 -0400
- To: Adrian Walker <adrianw@snet.net>
- Cc: Richard Lennox <listserve@richardlennox.net>, www-rdf-interest@w3.org
* Adrian Walker <adrianw@snet.net> [2004-05-20 10:46-0400] > Richard -- > > Actually, I think you may have put your finger on a general problem..... > > The general problem is, deductions that seem OK in RDF-ish notation are > sometimes OK in English, and sometimes absurd. > > There's a nice example from John Sowa about this: Clyde is an elephant, > elephant is a species, therefore Clyde is a species. That's wrong in > English, but there are ways of writing it in RDF/OWL that look OK. This is a classic example, stemming from two senses of 'isa'. Modern KR systems including RDF/OWL distinguish them carefully. In RDF, we have 'rdf:type' and 'rdfs:subClassOf' to represent two notions which might colloqially be described as 'is a' by an English speaker. In RDF, 'type' relates an individual to a class; 'subClassOf' is a relation between classes. Dan
Received on Thursday, 20 May 2004 10:44:29 UTC