From: Peter F. Patel-Schneider (pfps@research.bell-labs.com)
Date: 02/11/04
From: Sandro Hawke <sandro@w3.org> Subject: reifying variables Date: Tue, 10 Feb 2004 23:42:25 -0500 > > This came up at the end of the call, and Benjamin asked if I could be > more clear about it in e-mail. I'll try. The issue is about handling > variables in in RDF syntaxes. > > SWRL 0.5, at the start of section 6 says: > > "In this section we present an RDF concrete syntax for the > rules. It is straightforward to provide such an RDF concrete syntax > for rules, but the presence of variables in rules goes beyond the > RDF Semantics. We do not yet know if the intended semantics of the > resultant RDF graphs can be described as a semantic extension of > RDF." > > So SWRL makes no claim to get it right, which is okay, but of course > this means it's not really an "RDF Concrete Syntax", it's an "RDF-Like > Concrete Syntax." Not so good. Well, this is probably the best that can be done. As Drew said: > Making the triple be the fundamental unit of > meaning in RDF was a bad idea, and no reasonable solution to the KR > problem on the web can retain it. Note that it is the ``fundamental unit of meaning'' that is the cause of problems here. Triples are adequate (but not great) as encoders of syntax, but when they also have to carry all meaning they are inadequate in general, and inconvenient in just about every situation. peter
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