Time: 16:00 - 18:00
Thursday 6th March
Read Section 4. Meaning of RDF in RDF Concepts Last Call WD.
Read Bijan Parsia's Last Call comment.
Make changes to RDF Concepts section 4. (This is the perogative of the Working Group)
Make a consensus comment on RDF Concepts section 4, being:
This is intended to be minimalistic, in an effort to maximise the support for it, the intent is that where discussion in the meeting shows support for stronger text, then the text would be strengthened. In particular, this text is so weak, that suggesting it is intended to be nearly equivalent to suggesting striking section 4.
Pragmatics of RDF (informative)
RDF/XML documents are intended to be used for communication.
The communication is informed by: the formal semantics of RDF; a shared understanding of the effective meaning of URIrefs and literals in such a document; and a shared understanding of which system of entailements is being used.
The mechanisms by which the participants in the communication may share such understandings are outside the scope of this recommendation.
A majority position, and a minority position, i.e. no consensus.
Not even that.
Nature of defining information is separate issuette.
RDF Concepts 4.3 These social conventions are rooted in the URI specification [URI] and registration procedures [URI-REG].
Parsia: *how one fixes the meaning of the asserted graph* [...] to a *specific* grounded interepretation.
[...] are these social conventions true in all societies? Are you reporting, or specifying?
[...] How does this fit in with my ability to use any URI in my ontology, making any defining assertions I like about it?
The RDF last call documents do not indicate a method for indicating the formal definition of a URIref; however, section 4.2 does use the idea of 'defining information' for the social meaning.
RDF Concepts 4.2 An RDF graph may contain "defining information" that is opaque to logical reasoners. This information may be used by human interpreters of RDF information, or programmers writing software to perform specialized forms of deduction in the Semantic Web.
Parsia: Scare quotes are used to indicate that the enclose words are not being used in their normal sense. 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?
RDF Concepts 4.1 RDF/XML expressions, i.e. encodings of RDF graphs, can be used to make claims or assertions about the 'real' world. Such expressions are said to be asserted.
Not every RDF/XML expression is asserted.
Parsia: this section doesn't say HOW one asserts with RDF expression.
Patel-Schneider: How does an RDF expression get to be asserted? What syntax can I use to assert RDF expressions, or to prevent their assertion?
RDF Concepts 4.2 Issuing an HTTP GET request and obtaining data with a "200 OK" response code is a technical indication that the received data was published at the request URI; but data received with a "404 Not found" response cannot be considered to be similarly published information.
Swartz: I think the author of:
would considered it a published document.
RDF Concepts 4.4 Human publishers of RDF content commit themselves to the mechanically-inferred social obligations.
The meaning of an RDF document includes the social meaning, the formal meaning, and the social meaning of the formal entailments.
Parsia: Do you mean that only RDF(S) entailments can be logically drawn from an RDF graph? That's wrong, as with an OWL reasoner I can draw more conclusions. And, if we interpret logically strongly, e.g., as "reasonable" (distinct from formal) then I can logically draw *all sorts* of conclusions from an RDF graph that aren't sanctioned by the Semantics.
with HTML, I'm not committed to the mechanically-inferred conclusions of the HTML dom tree. So....?
A formal semantics does make it easier to reason about the *formal* meaning of an RDF expression. [...] It doesn't help with social meaning, though, contrary to 4.4:
Example (jjc) of last point - rdfs:comment is often used to describe a property or a class, and hence indirectly describe the participants in such properties or classes. In some cases, e.g. classes of properties, the levels of indirection of the description is greater. Without understanding the natural language in the rdfs:comment it is hard even to know which comments you need to understand.
RDF Concepts 4.2 A combination of social (e.g. legal) and technical machinery (protocols, file formats, publication frameworks) provide the contexts that fix the intended meanings of the vocabulary of some piece of RDF, and which distinguish assertions from other uses (e.g. citations, denials or illustrations).
The social machinery includes the form of publication: publishing some unqualified statements on one's World Wide Web home page would generally be taken as an assertion of those statements. But publishing the same statements with a qualification, such as "here are some common myths", or as part of a rebuttal, would likely not be construed as an assertion of the truth of those statements.
Parsia: Plus, *intended* meanings, by their nature *ALWAYS* can come unstuck from the conventions and formal/techincal structures of the meaning carrying expression. How does speaker's meaning (vs. sentence meaning) come into play. If I *intended* to refer to John when I say Mary, what have I done from the RDF point of view? [...]
But what if the social meaning of the set of explicit assertions is different from the set of those of the set of implicit assertion? heck, if people general work with a relevance logic (more likely than RDF entailment), then you *explicitly* don't always endorse/believe P & ~P even if you assert/believe each conjunct separately.
[Patel-Schneider - private communication] the difference between saying something explicitly and saying it implicitly [...] is often of paramount importance in social contexts
RDF Concepts 4.2 When an RDF graph is asserted in the Web, its publisher is saying something about their view of the world.
The social machinery includes the form of publication: [...]
Crowther: Consider a variant of the UMD DAML+OIL to OWL translator that takes DAML+OIL and/or KRSS as input and that produces OWL[/RDF] output. [...] Consider further that some public-spirited soul makes this available as a service on their Web site. Who is responsible for the 'social meaning' of the produced (and effectively published) OWL?
Parsia: a publisher may not be, and may *typically* not be the asserter. Indeed, what is it to be the *publisher*, in this context? The ISP? The web hosting company? The author of the document?
RDF Concepts 4.5 the person identified as C:JohnSmith might reasonably consider himself to be insulted.
Moreover, [...] the publishers of the third Web site [...] have insulted C:JohnSmith.
Patel-Schneider: there would be no way for any organization to deploy any RDF-based application. Such applications would not be able to understand the social meaning of the RDF they created or manipulated, and thus could easily create documents holding the organization liable for just about any imaginable consequence.
Parsia: (General comment) Does this mean, "Hey there, by the laws of the US and most countries of the world, if you publish RDF on your website, then you're committed to the mechanically-inferred social obligations"? If so, it's merely informative (and, in fact, probably false). If it's intended to *make it so*, then where do you get this authority?
Crowther: Social meaning is not something that a spec can influence, or should attempt to influence; that is up to the courts and the governments of our existing legal structures, not to W3C.
Parsia: (General comment) specifying much of anything about social meaning is an INCREDIBLY hard task. So either this section is vacuous (i.e., it doesn't really specify anything and thus can be ignored) or it's dangerously underthought and underspecified.
These are additional factors that I am aware of that have come up in conversation.