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Re: W3C specification error

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 22 Dec 2004 23:33:48 -0800
Message-Id: <p06001f15bdf0211d44de@[]>
To: Nord File <forhjoklan@yahoo.com>
Cc: www-rdf-comments@w3.org

>I know the following could seem a little stupid to you, but in my opinion
>the "rdfs:range" of "rdfs:predicate" being a not-better-specified
>just because reifications should be able to model statement errors is pretty
>letting horses having "things" instead of "feet", just because someone could
>erroneously state that a horse has four "frogs" attached to its legs - put
>it simple,
>it's conceptually incorrect...
>Can you please tell me where exactly is my mistake?

Sorry about the long delay in replying.

I think your basic mistake is in assuming that RDF is intended to 
enforce rationality. Part of the point of the semantic web is that 
information will be published all over the place and from many 
sources, not all of which can be assumed to be rational or properly 
formed. That is just asking too much, like requiring that all URIs 
will always get you a result and 404 errors should be illegal. Part 
of what makes the Web a success is precisely that it does not set out 
to be always right, and so it does not fail catastrophically when 
parts of it go wrong. There are network designs in which (the 
equivalent of) a 404 error would signal a world-wide disaster, a 
symptom of some huge breakdown in communication or failure of the 
network protocol. In the Web REST architecture, it just means some 
one has given you a bad URI or that some website is down; not a big 
deal. Similarly for RDF and the semantic web. RDF does not presume 
that all reified triples are properly managed, since some of them 
won't be; and so if it were assuming they were, inference failures 
would propagate. It does not set out to enforce them to be, because 
that would be inappropriate on an open network; and in any case, 
there is no way I or anyone else can enforce what you decide to 
publish. And finally, I would suggest that its not like the horses 
feet, because there could be genuine disagreements between you and 
whoever wrote the triples that you are referring to in your 
reification about what counts as a legal 'rdf:Property'. Presumably 
if they are not totally confused, they consider those things to be 
properties: but in YOUR world-view you might disagree.  You might 
have been using them as OWL classes, and OWL-DL does not allow 
something to be class and a property at the same time. But such a 
disagreement shouldn't prevent you from QUOTING what they are saying 
and making some comments about it (such as 'this is crap', maybe) . 
If RDF insisted as a matter of logic that the things in predicate 
position had to be properties, then just by referring to them, you 
would be forced to agree with them. That doesn't seem fair.

>Ok, that's all, I won't bother you anymore, I promise!
>Thanks again for your great feedback,

Hope this helps.  Happy Holidays.

Pat Hayes
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Received on Thursday, 23 December 2004 07:35:59 UTC

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