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Re: bbc-programmes.dyndns.org

From: Peter Ansell <ansell.peter@gmail.com>
Date: Sun, 22 Jun 2008 13:52:29 +1000
Message-ID: <a1be7e0e0806212052x481471d8p4db5ea079a079293@mail.gmail.com>
To: "Alan Ruttenberg" <alanruttenberg@gmail.com>
Cc: "Richard Cyganiak" <richard@cyganiak.de>, "Nicholas Humfrey" <Nicholas.Humfrey@bbc.co.uk>, public-lod@w3.org

2008/6/22 Alan Ruttenberg <alanruttenberg@gmail.com>:
>
> On Jun 21, 2008, at 10:42 PM, Peter Ansell wrote:
>
>> 2008/6/22 Alan Ruttenberg <alanruttenberg@gmail.com>:
>>>
>>> The target of foaf:page is a thing, a web page.
>>>
>>> If you write a literal string, you are saying the foaf page is that
>>> string.
>>> That's not what you want to say.
>>
>> Not if you type it with xsd:anyURI...
>
> The you are saying the page is an xsd:anyURI, not a web page.

You aren't saying that all RDF Resource (non-literals) are web pages
though. So why is saying that it is an RDF Resource supposed to
indicate that it is a web page?

>> Is there no separation allowed between the web and the semantic web
>> really?
>
> Need there be?

Clearly, there is a big wide world out there with a web that exists
perfectly fine with the semantic constrains ;) IRL!

>> I thought the semantic web was based on logic not web structures?
>
> Where did you get that idea?

By definition not all URI's are web structures, therefore the basis is
in a non-web scenario, of which web structures occupy a distinct
logical subset. RDF and OWL assume that there are abstract classes,
which are not web structures by any means.

>> The semantic web doesn't gain anything from the result of that page, which
>> clearly has an
>> alternative semantic representation available that you are already
>> looking at when you see the foaf:page (or whatever predicate allows
>> literals) statement.
>
> It isn't about the result of what you fetch so much as it is speaking
> clearly, as I said earlier. The domain of foaf:page is a document. Neither a
> string nor an xsd:anyURI is a document. End of story.

It is clear to me what the string means. And saying it is a
foaf:Document doesn't help with that at all. foaf:Page having a domain
of rdf:Resource doesn't have any more practical benefit than if it
didn't say what its domain was.

>> If you accept that the ontology you are using puts xsd:anyURI typed
>> literals into a given field it is perfectly meaningful to use the
>> string as you do any other URI string,
>
> If you use another ontology than foaf, with a different relation whose
> domain is an xsd:anyURI, and that relation is documented in such a way as to
> make sense, then sure. I don't happen to see what is gained by doing that.

The ability to have a string as you say which won't be presumed to be
a semantic resource identifier on its own which people can look at and
resolve themselves.

>> just in a context which won't be interfered with, or interfere itself
>> with, the logic based semantic
>> web rules.
>
> I don't know what you mean by "interfered with" or what connection you are
> making between this particular choice and logic based semantic
> web rules. It seems to me that the main benefit of using foaf:page here is
> that a lot of people know what it is supposed to mean.

Do they really gain the benefit specifically from its use as an
rdf:Resource though? Or do they really do a non-semantic retrieval of
the resource? Should they only expect to be able to retrieve machine
readable representations if they resolve this resource? How do you
actually say that a specific rdf resource doesn't actually direct to
an rdf representation as an idenfifier itself.

>>> The web page is
>>>
>>> <http://www.bbc.co.uk/programmes/b00b07kw.html> (the thing that the URI
>>> denotes)
>>
>> It isn't an RDF Resource any more than my street and suburb address
>> though, it is a simple human based locator which doesn't really have a
>> need or want to be an RDF Resource IMO.
>
> In both the case of the house, and the case of the web page, there is the
> resource - the house and the web page - and there is the address of the
> house and of the web page (also resources, but different ones). In
> discussion, one says different things about the address and the thing. For
> instance,
>
> "http://www.bbc.co.uk/programmes/b00b07kw.html" has 45 characters.
> or <http://www.bbc.co.uk/programmes/b00b07kw.html> uses the stylesheet
> <http://www.bbc.co.uk/programmes/r/23870/stylesheets/decor.css>
> or "http://www.bbc.co.uk/programmes/b00b07kw.html" is a name for
> <http://www.bbc.co.uk/programmes/b00b07kw.html>

I don't see why your convention of not dealing with URI's as strings
themselves really helps. Interestingly the difference between the RDF
resource identifier and the URL in the last one is what I am trying to
get at, just in the opposite way as the last statement is in the wrong
order for RDF.

> "32 vassar avenue, cambridge, ma, usa" has 36 characters or
> <the MIT Stata Center> foaf:depiction
> <http://en.wikipedia.org/wiki/Image:Wfm_stata_center.jpg>
> or "32 vassar avenue, cambridge, ma, usa"  entered into google maps, will
> locate <the MIT Stata Center>

And I am trying to say your last statement exactly. When entered into
a web browser the .html version will produce something they can look
at... Why is it different for addresses?

>> It is a coincidence IMO that it is defined in the same way that RDF
>> Resources are, and it isn't
>> useful to mix everything up by presuming that URL's of web pages are
>> useful as RDF Resources any more than arbitrary string literals.
>
> First, in the RDF world, everything is an rdf:resource, including
> rdf:Literals. So they are "mixed up" already. While there were perhaps
> mistakes made in RDF, that web pages are considered resources is most
> certainly not one of them. Finally, I'll point out once again that the issue
> here isn't what is or is not a "good" resource. The issue is speaking
> clearly. If you want to talk about the literal, by all means do so, and if
> you want to talk about the web page, likewise. But don't confused one with
> the other.

I have never quite understood the reason for putting Literals inside
of "Resources" when you can't say anything about Literals as a subject
except in reverse as the object of a statement and by common-sense you
should be able to state properties of Resources directly rather than
indirectly as RDF provides for the Literal subset.

I personally think its a bad idea to smudge the differences by saying
all web pages are semantic resources, as they aren't... Many have no
inherent RDF semantics whatsoever and hence can't be reasonably used
as the subject of statements. It would be much better if by default
they were thought of as Literals and kept as objects of statements in
semantic terms.

Peter
Received on Sunday, 22 June 2008 03:53:04 UTC

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