- From: patrick hayes <phayes@ai.uwf.edu>
- Date: Mon, 13 May 2002 01:45:45 -0500
- To: Drew McDermott <drew.mcdermott@yale.edu>
- Cc: www-rdf-logic@w3.org
>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