- From: Jim Hendler <hendler@cs.rpi.edu>
- Date: Mon, 26 Nov 2007 12:00:52 -0500
- To: "OWL Working Group WG <public-owl-wg@w3.org>" <public-owl-wg@w3.org>
- Message-Id: <A80EEDE0-78C6-4B64-AE53-C5FECF636142@cs.rpi.edu>
I have taken a long time to answer this question, because I had to count to 10, and then count to 10 again -- I've now reached somewhere around 10^^6 and am calm enough for an answer - in fact, several: ANSWER 1: Someone like me wants a reference manual OK, Bijan argued that since users will mainly use OWL through tools, they didn't really need to know most of this. Ok, maybe, but suppose I got to a SWOOP or Protege for OWL1.1 and create a new property - I get a menu asking me what kind of property it is. One of my choices is owl11:irreflexive property. hmm, I vaguely remember that reflexive and irreflexive were things I learned about in college math over 30 years ago, so I had better check the documentation to see if this is what I want. The overview gives me something like an example IrreflexiveObjectProperty(husbandOf) which confuses me a bit because the term my editor shows me is "irreflexiveProperty" but even assuming these are the same, this one example doesn't tell me anything. (and the example for Reflexive is "knows" which happens not to be a reflexive property in many systems, but I digress) In the structural document all I can discover is that it is syntactically legal in some syntax I don't use (remember, I'm doing this through an editor as Bijan argued, so I don't see any syntax except what is displayed by the editor). So that doesn't help. Gritting my teeth, I go to the model-theoretic semantic (most users by now would have simply decided not to use it, but I'm a bit stubborn). I find there (in a table, which means my browsers search didn't find it so I had to scroll through the whole document) that x ∈ ΔI implies ( x , x ) is not in RIpo (sorry for the syntax, but that's how it comes out when I cut and paste to mail it to someone who might be able to answer the question). Well maybe from that I could figure out the answer if I was slightly less stupid, but I'm still confused, I check the RDF mapping, but it also only gives me syntax. So now I go out on the Web and find some definition of irreflexive and I finally get it -- time wasted because there was no manual - on the order of 30-45 min. And that's for one of the easy one (try ObjectExistsSelf where { x | ( x, x ) ∈ RIpo } is the only explanation) There's a lot of functions in this thing named after math I'm not familiar with and defined only in a logic I'm not familiar with. My conclusion - to hell with OWL, make up my own stuff in RDFS. ANSWER 2: My students - a guide Ok, I give a lecture in class, I give some examples, I assign my students to go write an ontology. Oops. every one of them has the problem above in spades - not only don't they understand this stuff, but they don't have my experience with OWL. So they puzzle out what they think things mean, but they want to try it -- boy, would be a lot easier if they had some examples they could cut and paste into something (validator, etc.) so they could not only figure out the meaning, but also puzzle out the syntax. ANSWER 3: People considering use of OWL for a project - better overview Dean Allemang and I are in the finishing stages of a book about how to use OWL 1.0 -- we were motivated because in teaching professionals interested in using the Semantic Web (usually the decision makers for their companies or people who report to the decision makers) we found that they had read the overview, decided they liked the idea of OWL and wanted to take a course before they dove in. (They then wanted something that emphasized the stuff we had in the course, so we wrote the book). We've been teaching the course for several years now, we are finally getting the book done, but again, these users have usually read the overview - so the book alone wouldn't have been enough for them - they needed something to whet their appetites. In general these people are business people working for companies or for the government. They are well-educated professionals (college grads in general, usually some sort of professional masters, occasional PhD in engineering or some non-CS field) with a high level of domain knowledge, and usually some programming background, but they've rarely taken a logic course. These users have a lot of demands on their time, without a simple thing to look at and decide they want to learn more, they usually end up doing something else. A number of them have Shelley Powers' RDF book and are pretty much convinced by RDF/RDFS but are a bit skeptical of OWL (and I fear will be much more so of OWL 1.1 because the more complex a language, the higher the learning curve, and many of these folks are learning-curve adverse because of the time it takes) So there's my top 3. I've left out Web Application developers because in my experience they will mainly ignore all our documents and just use the pieces of the RDF (OWL Full) vocabulary that make sense to them, and ignore the rest - however, if there is a reference, they do tend to make sure that what they think is being defined is right - i.e. they would like to make sure the operational semantics of what they develop matches as close as possible to the reference manual. -JH p.s. I note that the OWL Reference and Overview are the two highest ranked in Google and interestingly the S&AS document, despite being normative, is lower in Google rank than any of the others except for Use cases, with which it is tied... I know Google rank is variable and also not a definitive argument for anything, but it does indicate more people linking to the user facing documents over the developer- oriented one. Doesn't deny the importance of that document, just stresses the importance of the others to uptake... "If we knew what we were doing, it wouldn't be called research, would it?." - Albert Einstein Prof James Hendler http://www.cs.rpi.edu/~hendler Tetherless World Constellation Chair Computer Science Dept Rensselaer Polytechnic Institute, Troy NY 12180
Received on Monday, 26 November 2007 17:01:30 UTC