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Re: When does a document acquire (web) semantics?

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 2 Feb 2010 01:06:01 -0600
Cc: w3c semweb HCLS <public-semweb-lifesci@w3.org>, Oliver Ruebenacker <curoli@gmail.com>
Message-Id: <657C0474-4DFA-4352-8782-904151CC2028@ihmc.us>
To: John Madden <john.madden@duke.edu>

On Feb 1, 2010, at 3:53 PM, John Madden wrote:

> Hi Oliver,
> I don't want to speak for Eric, and I'm not even sure I've  
> accurately represented his point here. Nor am I sure that they *are*  
> different scenarios.
> Instead of saying they are or aren't, let me throw out a scenario  
> that concerns me, and in the context of which they *might* be  
> different, and ask for people to comment.
> Suppose I publish a medical document in English, and purport to  
> attach to it an "official" RDF/OWL graph.
> 	A problem (sidebar):
> 	Is this possiible? If so, what makes it "official"? Not sure. Maybe  
> the graph is connected to the document
> 	with grddl transform that I have published, which makes explicit  
> the rules I use to go from English to RDF.
> 	Maybe the graph contains some assertions that reference some  
> provenance/trust vocabulary, such that
> 	triples are contained in it that assert -- in some way -- that it  
> is a privileged graph. Maybe the RDF/XML
> 	document has an XMLSig on it and I've stated to the world that I  
> nobody is allowed, under penalty of my
> 	wrath, to represent this document by RDF/OWL graphs except provided  
> that ones I've signed are provably
> 	consistent with them (which is an inane thing for me to do, and not  
> only because I don't know anybody who
> 	is afraid of my wrath.)
> 	(For a medical document, it might not be *me* that insists on this  
> claim; it might be my employer/hospital.
> 	They don't want people attributing meanings to the document other  
> than those they have had a chance
> 	to approve, because they don't want somebody claiming the RDF/OWL  
> they published led to a subsequent
> 	adverse event (by, e.g. being used in a decision support system at  
> some later time that attributed a different
> 	meaning to some vocabulary item). So for example they might only  
> allow locally defined classes properties
> 	to be used in the graph.)
> Anyway, I somehow put a stake in the ground and loudly assert that  
> **this** is what it means.
> Now later Eric comes along and wants access to my document, and many  
> others in a bunch of different databases, because he is aggregating  
> data about patient encounters for a research project of his. In his  
> SPARQL query, he does a bunch of joins, that in effect are mappings  
> between the local vocabularies in the existing RDF graphs and  
> whatever vocabularies he's attempting to aggregate to. In this  
> process, my "official" RDF triples get left behind.
> 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.

Now, however, that said, the Web (and hence the Sweb) does give some  
useful structure, in that every URI has an owner, and its not a bad  
presumption that what the owner of it says using it  might have more  
legitimacy than what others say using it. in cases of doubt. (This  
doesnt always work, but its not a bad heuristic.) So it might be a  
good idea to take Eric's publications using Eric's URI as having more  
authority on what that URI refers to, or at any rate being a more  
accurate reflection of what Eric intended them to mean.

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.

Pat Hayes

[1] www4.wiwiss.fu-berlin.de/bizer/SWTSGuide/carroll-ISWC2004.pdf

> John
> On Feb 1, 2010, at 3:14 PM, Oliver Ruebenacker wrote:
>>    Hello,
>> On Mon, Feb 1, 2010 at 1:30 PM, John Madden <john.madden@duke.edu>  
>> wrote:
>>> We had an interesting call in TERM today. One of the topics I  
>>> would like to boil down to the question "When does a document  
>>> acquire its semantics?" or, "when does a document come to mean  
>>> something?"
>>> I argued the (admittedly intentionally) radical view that  
>>> documents have no semantics whatsoever until a reader performs an  
>>> act of interpretation upon the document, which in the Semantic Web  
>>> world would be the same as attributing an RDF/OWL graph to the  
>>> document.
>>> Even if the author of the document attributes a a particular RDF/ 
>>> OWL graph to her won document, I argued that this graph is not  
>>> privileged in any way. That others could justifiably argue that  
>>> the author's own RDF/OWL graph is incomplete, or flawed, or  
>>> irrelevant, or even incorrect. And the same is true of any  
>>> subsequent interpreters (i.e. authors of RDF/OWL graphs that  
>>> purport to represent the "meaning" of the same document).
>>> Eric argued a really interesting point. He argued (and Eric,  
>>> correct me if I'm interpreting you wrong here), that semantics  
>>> instead come into existence (or perhaps *can* come into existence)  
>>> at the point when somebody executes a SPARQL query on a set of RDF/ 
>>> OWL graphs. That is to say, maybe I'm wrong and semantics doesn't  
>>> even come into existence when somebody attributes an RDF/XML graph  
>>> to a document; but rather it only comes into existence when  
>>> somebody queries across (possibly) many graphs of many different  
>>> people.
>>> What do you think?
>> Can you give an example were this difference is relevant?
>>    Take care
>>    Oliver
>> -- 
>> Oliver Ruebenacker, Computational Cell Biologist
>> Systems Biology Linker at Virtual Cell (http://vcell.org/sybil)
>> Turning Knowledge Data into Models
>> Center for Cell Analysis and Modeling
>> http://www.oliver.curiousworld.org

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Received on Tuesday, 2 February 2010 07:07:08 UTC

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