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Re: Social meaning discussion 6th March

From: Tim Berners-Lee <timbl@w3.org>
Date: Sat, 01 Mar 2003 19:12:33 -0500
Message-ID: <3E614C70.6010602@w3.org>
To: Jeremy Carroll <jjc@hplb.hpl.hp.com>
CC: Dan Brickley <danbri@w3.org>, Brian McBride <bwm@hplb.hpl.hp.com>, pat hayes <phayes@ai.uwf.edu>, Bijan Parsia <bparsia@isis.unc.edu>, Graham Klyne <GK@ninebynine.org>, RDF Core <w3c-rdfcore-wg@w3.org>

Jeremy Carroll wrote:

> tbl:
>>>> 2. The meaning of the statement is defined by the definition
>>>> of the predicate, as applying to the subject and object identified 
>>>> by the
>>>> definition of the subject and object terms.
> Danbri:
>>> This for me is the crux: do we mean the machine oriented 'definition'
>>> in RDFS or OWL or N3, or some more rounded/scruffy/social notion of 
>>> definition.
> I find Bijan's observation compelling
> [[
> But there's no vague, much less precise, definition of "defining 
> information". And I'm a logical reasoner, will this information be 
> opaque to me? (Well, if in German, yes, but *all* human reasoners?)
> [...]
> So it's formal meaning isn't fixed IN ANY WAY by the "authority"? And 
> the social meaning?
> ]]

There seem to be a confusion here that things have two meanings, a 
"formal" one
and a "social" one.    I don't think that is useful.  Something has one 
"inverseProperty" can be defined mathemaically, but remember that  the
mathematical symbols used are probably defined in english somewhere.
"color" can't be defined formally in terms of mathemaics, unless you have
assume a lot of other terms to do with spectral reflectivity and light.

> Two points:
> - "whatevers available" is simply not clear enough. 

There are a lot of social systems for relating definitoins to terms.
These include domain name owndership, the Web, etc.
The web is a big place.  Predciates and terms vary enormously.
For RDF to be able to describe real things, it is essential that
some terms be defined in english.  Look at the cyc ontology.
I'm not sure what you are unhappy with, here.
Are you saying it is not clear enough?
Are you saying that
it is not clear what the definitions of the terms are?
Are you saying that the english definitions should not be allowed?
Or do you want a clean algorithm for determining which
english documents define a given term, from the web?  (That we could 

> - RDF has decided to avoid the notion of definition for the formal 
> semantics, we shouldn't then have it in the informal semantics.

Well, every specification upon  which the web has depended up till now, 
Ethernet and unicode and TCP/IP and HTTP has had the meaning of its terms
and structures explained in english, informally.  These specs have been used
to build software, resolve many discussions,  and so on.  There are a 
mass of
RDF schemas and related documents going to be written -- but it needs 
the RDF
spec to pass on the authority to them to define their fields.

Just because *some* aspects of the meaning of *some* RDF terms can
be expressed formally   does not remove the duty of the RDF spec to
say what an RDF document means.

The formal semantics cannot define "color".

Suppose I send you an RDF document syaing (in n3)

<http://example.info/ips/gg5#y004> <http://example.com/dsaf#enFap> "176".

How would you know what I was telling you?
How would someone who had not heard of RDF before?
The mime type would take them to the RDF spec and -- then what?

> For me, either of these is fatal. This cat has had its nine lives.

Fatal for the idea of defining what an RDF document means?
How sad.
In that case, I suppose we had better start all over again, as
we have ended up with a languge of meaningless documents.

If  RDF is only be to be used to encode mathmeatical
formalisms,  and not information about the real world,
do we need another langauge to express data?


> Jeremy
Received on Saturday, 1 March 2003 19:13:14 UTC

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