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Re: help wanted: RDF issue rdfms-assertion

From: Tim Berners-Lee <timbl@w3.org>
Date: Wed, 29 May 2002 13:18:10 -0400
Message-ID: <052501c20734$cf06ac10$0301a8c0@w3.org>
To: "Brian McBride" <bwm@hplb.hpl.hp.com>
Cc: "RDF Core" <w3c-rdfcore-wg@w3.org>, "Dan Connolly" <connolly@w3.org>, <www-rdf-logic@w3.org>

----- Original Message -----
From: "Brian McBride" <bwm@hplb.hpl.hp.com>
To: <timbl@w3.org>
Cc: "RDF Core" <w3c-rdfcore-wg@w3.org>
Sent: Tuesday, March 26, 2002 1:38 PM
Subject: help wanted: RDF issue rdfms-assertion

> Tim,
> The RDFCore WG seeks your help with an RDF issue, rdfms-assertion:
>    http://www.w3.org/2000/03/rdf-tracking/#rdfms-assertion
> [[
> Summary: RDF is not just a data model. The RDF specs should define a
> semantics so that an RDF statement on the web is interpreted as an
> assertion of that statement such that its author would be responsible in
> law as if it had been published in, say, a newspaper.
> ]]
> The WG believes that this issue originates with you.
> I would like to clearly establish what it is that you would like from us.
> A number of concerns have been raised about this issue:
>    o RDF is just one of several specifications that are 'in play' when an
> RDF statement is retrieved from the web.  What is the minimum the RDF
> must say to achieve the effect that you want.

I think that it should say that the predicate determines the meaning of any

It should specify in the specific case of predicate rdf:type that the
definition of rdf:type is that the object determines the meaning of the

It should then hand off to the URI spec to say that "determines" above means
that those publishing issuing or owning terms are the ones who definitively
define (through specs etc) what they mean.  Issues of
ownership, and dereference are covered not in the RDF spec but
directly or indirectly in the URI spec.

>    o Whilst the RDF specs might say what a statement means, that meaning
> might be modified by its context.  For example, what about an RDF graph
> entitled "Myths about Namespaces".  Would the publisher of that graph be
> asserting the statements therein?

*** The role of the RDF spec is to state what an RDF document means. ***

The role of SMTP spec to say that a message delivered under certain
circumstances is
a message from one party to another.

In other words, other protocols deal with the question of who is asserting
Typically these things are complex and recursive, but the common point of
reference is the meaning of a document.

>    o Some on the WG do not believe that the WG is empowered to make law;
> that is a matter for the lawyers, governments, parliaments and the like of
> the many countries of the world. Different countries may make different

They are right, RDF Core cannot determine the punishment to meted out to
an individual who makes a false statement in  given case and
a given jurisdiction. However, it is vital that RDFCore explain concisely
unequivocally the algorithm for  determining the meaning of an RDF document,
so that legal folks have a sound base for their own arguments, but no
basis for wriggling out between the specs.

Note that RDF specs are referred to by XML specs (via the namespace)
which are referred to by the MIME registry which is referred to by the HTTP
spec which is referred to by the TCP port registry, which is referred to
by the TCP spec, which you effectively agree to when you get an IP
So there is a well accepted and important chain of delegation, in which
RDF plays a role of one link.

(See my www2002 keynote)

>    o Do you expect us to define exactly what an RDF statement means?
>     _:b <rdf:type> <foo:Liar> .
>     _:b <foo:email> <mailto:bwm@hplb.hpl.hp.com> .

Yes. By delegating to the specification of the Properties and Classes
used as predicate and (in the case of rdf:type predicate) object.

> What chain of evidence would be required to prove that this is  a
> derogatory statement about me.

The chain would be  that I mentioned above showing that the
definitions of foo:Liar and foo:email define the meaning of the document.

To then show an HTTP response from server for foo, which has
been, though established social procedures and technical specs of DNS been
delegated the ability to publish information by the owner of the foo.
That response could contain information in a suitable language which
indicated that
foo:Liar was a class of people who were liars, and that foo:email was
an emailmox which a person used, then the chain would be complete
about the meaning of the document.

There is a simple step to show that no one else has your mailbox.

Now suppose that document were published by sending it to
a public email list.  There is an indisputable body of history which
accepts that such a message is considered a public assertion by the sender.
So you could sue.   You couldn't if the document were sent in an attachment
as attachments break the chain, unless there is a something in the cover
(e.g. "I agree with the enclosed") to connect the chain of assertion.

It is arguable what happens if it is published
on a website.  Normally it is clear (for example though links from someone's
home page) which documents published are deemed to be asserted, and which
are archive copies of other people's things, for example.  In other cases,
there is explicit link from elsewhere -- such as a chumping in IRC which
agrees with the doc.

> The current model theory WD
>    http://www.w3.org/TR/rdf-mt/
> in section 1.3 states:
>    [[Asserting an RDF graph amounts to claiming that it is true, which is
> another way of saying that the world it describes is, in fact, so arranged
> as to be an interpretation which makes it true.
>    ]]
> Is this sufficient to meet your needs?

No.  I would not want the above to be dependent on the Model Theory at all,
but asserted in the RDF spec.

The model theory does not as far as I know have such a spec hand-off, which
is essential to the meaning of RDF.  It only considers things you can know
by only taking into account the RDF spec, and so, while it gives a mapping
of RDF into set theory, it does not as far as I could see explain what an
RDF document means.  (Maybe I am wrong and I missed it).

> Other means would be needed to
> establish that a statement was about the world we live in and that it was
> being asserted.  It seems that such claims could only be established from
> the context in which the statement was used.

So RDF for those claims relies on other specs which invoke RDF.
The RDF Core group should just define the meaning of an RDF document.

> The RDFCore WG has discussed other possible statements that it might
> make.  The following text, which might be included in the primer,  was
> suggested for discussion:
> [[
> Assertions made in RDF are analogous to assertions made in any other
> language. The author and/or publisher of these assertions is responsible
> for these assertions. It remains the responsibility of courts to determine
> legal responsibility considering the effects of context and other factors.
> ]]

I think reference to the other specifications which invoke RDF is more
useful here.
It is *NOT* a good idea to give the slightest indication that you leave to
the courts
any discussion of the connections between IP, TCP, SMTP, MIME, XML and RDF

> Brian McBride
> RDFCore co-chair

Tim Berners-Lee
Received on Wednesday, 29 May 2002 13:17:13 UTC

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