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Re: What *is* RDF?

From: Richard Cyganiak <richard@cyganiak.de>
Date: Thu, 31 Mar 2011 13:23:51 +0530
Cc: <msporny@digitalbazaar.com>, <public-rdf-wg@w3.org>
Message-Id: <5C935591-A60D-43BA-BDE6-D05B89E882B6@cyganiak.de>
To: Peter Frederick Patel-Schneider <pfps@research.bell-labs.com>
Hi Peter,

This is nice. (And, I think, almost totally off-topic, but hey the chairs said it's ok to go off on tangents up to the F2F.)

A few comments/questions inline.

On 25 Mar 2011, at 22:19, Peter Frederick Patel-Schneider wrote:
> The predicate (or property) of a triple can only be a blank node.

!!!

> Aside from strings with a langauge tag, the identifiers for these
> are borrowed from XML Schema datatypes, but datatypes can be extended at
> will.  It is best not to use this extension facility, and to restrict
> oneself to strings with language tags plus the built-in boolean,
> numeric, string, and date datatypes of XML Schema datatypes.

What's the reasoning behind the assertion that custom datatypes are best avoided?

> All other parts and uses of the built-in vocabulary are controversial
> and best avoided.

I hope you didn't mean to indicate that rdfs:label, rdfs:comment and rdfs:isDefinedBy are best avoided?

> There is a full-fledged logic that provides the formal meaning for RDF
> graphs, specified by the RDF Semantics document.  [...]  For various
> historical reasons, this document divides the meaning into several
> sections, but this division can be ignored.  

What exactly do you mean here? The division into RDF entailment, datatype entailment etc?

> This document also does not define a full set of datatypes.  

I don't understand what you mean by that. It defines the XSD datatypes (by reference to XML Schema). Why is that not a full set of datatypes?

> The document is missing a few bits that many users of RDF(S) consider to be part of RDF(S), notably a notion of equality.

Do you mean graph equality? Which other bits are missing?

Cheers,
Richard
Received on Thursday, 31 March 2011 07:55:35 UTC

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