- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Fri, 07 Dec 2001 12:22:16 -0500
- To: bert@w3.org
- Cc: connolly@w3.org, phayes@ai.uwf.edu, janet@w3.org, em@w3.org, liam@w3.org, www-webont-wg@w3.org
(By the way, I do appreciate the attempt to get something about RDF, ontologies, and W3C's Semantic Web activity into a widely-distributed document.) From: Bert Bos <bert@w3.org> Subject: Re: review of XML in 10 points [was: AGENDA...] Date: Fri, 7 Dec 2001 17:35:56 +0100 [...] > I will mull over your text (thanks!) and see what changes it suggests. > At first sight, though, it doesn't look as different as your use of > "rubbish" had suggested. I think that you have severely underestimated my disagreements with the paragraph in question. I'm going to make another try at stating my disagreements. XML is the basis for RDF and the Semantic Web XML provides an unambiguous syntax [What is unambiguous doing here? Any syntax should be unambiguous.] for W3C's RDF, the language for expressing metadata [RDF may be W3C's language for expressing metadata, but it is certainly not the only one, and not the only one that was designed for use on the web.] (in fact, for knowledge in general). [This claim---that RDF can express knowledge in general---is the most dangerous kind of hype. Readers who know little about the topic will take away the impression that expressing knowledge is a solved problem, which it certainly is not. Readers who know more about the topic will take away the impression that W3C is clueless in this area, which I hope it is not.] RDF is like hypertext elevated to the next level. Whereas hypertext links pieces of text and leaves their relation vague, RDF can link anything and everything [This statement is again hype, but not nearly so dangerous as the hype above. RDF doesn't link anything to everything. It can, perhaps, link formal objects can be considered to denote something to other formal objects. ] and assigns names to the relations: [RDF also doesn't assign names to anything. At best one could say that RDF can provide distinguishing tags on the relations and relate these tags to each other in interesting ways.] 'A is the price of B' can be a relation between an object and a sum of money; 'A is heavier than B' can be the relation between two sumo wrestlers; 'A is the cause of B' can be the relation between a shower and your being wet. [These examples severely overstate the reach of RDF in several ways. RDF does not yet address typed data, needed for a decent handling of the first example. RDF cannot do any causal reasoning, and cannot even represent states of affairs.] To communicate knowledge, whether in XML/RDF or in plain English, both people and machines need to agree on what words to use. [Here there is a severe understatement. Agreement on the words is insufficient---agreement on meanings is needed instead. (Think of false cognates in natural laguages.) Using ``words'' for machine communication is also a form of hype---machines do not yet have access to the richness of natural language, which is evoked by the use of the word ``word''.] A precisely defined set of words to describe a certain area of life [Again ``words'' is not an appropriate word to use here. As well ``life'' is one of those words that carries a gigantic halo of meaning along with it and should be avoided when talking about the current capabilities of machines.] (from 'shopping' to 'mathematical logic') [I'm not sure if ``mathematical logic'' qualifies as an ``area of life''. In any case, RDF is totally inadequate for expressing any significant portion of mathematical logic.] is called an 'ontology.' [An ontology is not really a ``precisely defined set of words'' or even ``a precisely defined set of terms''. However, for a paragraph of this sort the difference may not be worth worrying about.] RDF, ontologies, and the representation of meaning so that computers can help people do work are all topics of the Semantic Web Activity. [Agreed, at least to some reasonable approximation.] In my view, the biggest change between the paragraph above and the paragraph that I produced is that I drastically reduced both the scope of and claims made for RDF. Peter F. Patel-Schneider Bell Labs Research
Received on Friday, 7 December 2001 12:25:14 UTC