I am a little bit slow because I don't really know what is the argument?
Is their essential difference between
(1) A user performs an act of interpretation
(2) A user executes a SPARQL query
Isn't "execution of SPARQL query" an "act of interpretation"? I think
so, hence I don't know what is the fuss is all about.
Of course, one of the implication from the argument (at least it seems
to me) is that document has semantics iif there is an RDF/OWL bound to
it. I think this is absolutely false.
RDF is itself purely syntactic. RDFS/OWL is the attempt to piggyback
formal logic on RDF. But semantics doesn't have to be rooted in formal
logic. By Wittgenstein's thesis of "Meaning is use", semantics is
determined by a user's action. If a thing, document or not,
consistently triggers a certain action/interpretation, then its
semantics is clear. But here, clarity/ambiguity is relative -- relative
to an intended ontological ground. A coarse grounded ontology is more
likely to be used consistently but less likely to trigger a specific
action consistently. Conversely, a fine grained ontology is more likely
used to trigger a specific action, but it is less likely to be used on a
larger context.
Hence, does x (anything you can think of) has semantics? Yes, of course,
because "x is a Thing" is a semantic statement -- in fact, very
consistent one. Now, let's coming back to the original question, when
does a document acquire its semantics? It acquires whenever it is made.
The issue, then, is not a matter of when but what kind of semantics it
has acquired.
Xiaoshu
On 2/2/10 8:25 AM, John Madden wrote:
Is this a possible scenario? Where does it fail? Is it that the SemWeb doesn't support any notion
of an "official" graph? Is it that there is no such thing as an "official
graph" at all (on the sem web or anywhere else)?
It doesn't, and there isn't. The SWeb position on official is exactly the same as the Web position, which
might be summed up in the phrase Caveat Lector. Publication is easy and free and unfettered, and requires no
imprimateur or legitimacy. So, its up the reader of what is published, to decide whether or not to accept it,
whether or not it is trustworthy, etc.. This is why the top level of TimBL's layer cake is labelled
"trust" rather than, say, "authority" or "legitimacy". And this is, of course,
much like publication elsewhere, at least in the free world.
Pat, thanks. That's what I thought, and in fact that's the way I like it. It
does raise an interesting question in the medical realm. Usually doctors don't
express their thoughts in RDF; they usually write in (some domain-specific
dialect of) English. They publish the resulting documents, giving them a
signature.
The resulting English language document *does* have a special status. For example, some
doctor (#2) takes an action that he/she claims to base on some assertion in a document
authored by doctor #1. Something bad happens. Doctor #2 now claims the responsibility
lies with doctor #1's report, which was (claimed to be) inaccurate (contained an
objective falsehood). Doctor #1 at this point would very likely produce the original
report text, and ask if doctor #2 actually read it. Maybe they'd argue about whether #2's
"reading" of the document is reasonable or nor.
That's all pretty routine. It gets interesting when in addition to the original
English language document, doctor #1 also publishes some rendering of that
document in RDF. What exactly is the relation between the RDF rendering and the
original document?
I think the best way to think of the RDF -- any RDF, including the author's own
RDF rendition of his very own document -- is that it is an interpretation of
the original. And no interpretation is any more privileged than any other. That
includes the author's own. So, like you say, caveat lector.
This makes it rather difficult to use RDF in clinical care. With English
language documents, we reject those that are not signed and original (or
faithful copies of the signed original) for purposes of clinical care. But in
the SW world, there is no special status. You can't sign it. You can't
guarantee that your triples will stick together, or be picked apart. You can't
even expect to know where a particular triple came from (who was the original
assertor of the triple).
One of the motivations for the named graph proposal was to provide exactly the
kind of authoritative warrant of assertion that is discussed in the above
sidebar, by the way. [1]. Y'all might want to check it out, I think it was
quite ingenious. BUt no doubt too complicated for immediate adoption by the
Sweb community in its current incarnation.
I think the named graphs proposal was a great piece of work, speaks directly to
this, and I wish it had more uptake. It solves a huge piece of this puzzle.
There still remains the issue of what the relation is between the named graph
and the original (English) document is, but at a minimum it allows some graphs
to be marked with a special status.
In the interim, the closest we can come to named graphs currently seems to be
the RDF document as a unit of communication. Most of the work in HCLS has so
far has focused on the benefits you can get from aggregation, i.e. from
specifically treating RDF documents as having no distinct identity one from
another. For the clinical (as opposed to the research) use case, we do need to
start thinking about ways to use RDF documents that preserve their identify qua
documents.
John
