Re: rdf inclusion

>Jeff's response to Pat's "dream world" comment reminded me that I
>hadn't responded.
>
>      [Jeff Heflin]
>      >In terms of merging RDF graphs, daml:imports means you can't add that
>      >triples from some graph unless you also add all the triples from the
>      >graphs of the resources that are imported.
>
>    [Pat Hayes]
>    But wait a minute.  What does it even mean for your ontology to say
>    what my reasoning engine can or cannot do? Of course I CAN add
>    triples from one graph without adding triples from another. All that
>    any ontology can do is to express some propositional content. What
>    another engine does with that content can be reasonably expected to
>    conform to the semantics of the language, but that's about all. If
>    the engine decides to ignore some of what you say, that's it's
>    business, not yours. Ignoring part of any RDF graph is perfectly
>    valid considered as an inference, after all: an RDF graph entails all
>    its subgraphs.
>
>I would disagree with Jeff on technical grounds: the daml:imports
>statement states what is *not* to be included, as opposed to what
>*must* be included.  That is, it points to a DAML+OIL document, and
>says that any triple outside this document is not encompassed by the
>import unless specifically authorized by daml:imports within that
>document.  As I've said elsewhere, this leaves open the possibility
>that the document uses proper-name URIs from other, unimported
>documents.
>
>However, pragmatically, Jeff has a point: If my inference engine fails
>to draw an inference, and the inference follows from premises I have
>in hand plus stuff from an imported ontology, I can't call up the
>tech-support staff for the ontology

Look, you are having a problem with your inference engine, right? So 
why are you calling the tech-support for the *ontology* ?? The 
conversation ought to go like this:
Drew: "My inference engine didn't conclude....."
Tech Support: "Excuse me, sir. This is the *ontology* support number. 
Is your inference engine certified valid?"
Drew: "Sure."
Tech Support: "Did it draw any conclusions that you consider to be incorrect?"
Drew: "No, it didn't draw any conclusions."
Tech Support: "Sorry, sir, we make no warranties about inference 
performance, only about correctness. You need to talk to whoever 
wrote your inference engine. Have a nice day."

>and expect much if the
>conversation goes like this:
>
>    Me: "My inference engine didn't conclude P when it clearly follows
>       from premises Q1 and Q2.  Q1 is in my local dataset, and Q2 is
>       in your ontology, which my dataset imports."
>
>    Tech Support: "What exactly does your inference engine do with Q2?"
>
>    Me: "Oh. It ignores it.  Pat Hayes said I was free to do that, and
>       it did make the implementation of my inference engine much
>       simpler."
>
>    Tech Support: <dial tone>
>
>    [Pat]
>    I think this entire discussion is in a dream world. First, there are
>    no clear notions of definition to appeal to.
>
>And none needed.
>
>    Second, no ontology can restrain the actions of a remote inference
>    engine. 
>
>True but irrelevant.
>
>    Third, why would one want things to be different?
>
>Because it's not a matter of "restraining" anyone.  If ontologies are
>posted with well-defined semantics, and people advertise inference
>engines that claim to use those ontologies, then consumers should have
>a reasonable expectation that the inference engines respect the
>semantics

Yep

>and draw mostly useful inferences

Nope, because this is meaningless. When I publish some content, I 
have NO IDEA what use someone else is going to make of it, nor could 
I possibly have any such idea. There is no well-defined concept of a 
'useful inference', so no expectation that only those will be drawn.

But in any case, the 'customer' here is going to be using two things, 
got from different sources: the inference engine (a piece of software 
probably costing some real money, like a web browser) and some 
content (provided free from a website, probably, like a web page). If 
the former doesnt perform properly its the fault of the software 
vendor, not the website.

>that mostly don't require
>an exponential amount of work.  It's in everyone's interest to play by
>the rules.  Am I missing something?

Yes. You are missing the fact that there are no rules to play by.

Pat

Received on Monday, 13 May 2002 11:32:49 UTC