From: Jim Hendler (jhendler@darpa.mil)
Date: 02/05/01
>s) > >The operational difference appear, to me, to be two-fold: > >1/ Combination classes cannot be formed in Ian's and my approach. That is, > you can't create the class of ``integers greater than 15 or people with > two brothers who are doctors''. > >2/ The only concrete classes that can be formed are those that are part of > the concrete type system (in this case XML Schema datatypes). That is, > you can't create the class of integers who used to be the number of > employees of AT&T at the beginning of every month in the last year. > >My view (and I think that Ian and Deb would agree) is that these classes >are not very useful, or at least that they can be avoided. In particular, >the second class would much better be modelled as a sequence of integers, >not as a class of integers. Even if you really want an unordered >collection, an existential set (i.e., not an intensional class) appears to >be a suitable choice. > OK, I'm beginning to get it -- but here's the issue, in my paper http://www.cs.umd.edu/~hendler/AgentWeb.html I describe the sort of application I want to do with the ontology language. A key point is my being able to check whether inputs are legal within some defined range. For example, I have a service with two parts. First, it check to make sure that you enter a legal date in February of 2001 (i.e. an integer between 1 and 28). Then it checks to see if you enter a legal Credit card number (for now let's ignore format and say an integer between 0 and 999999999999999). I realize I don't have to define a type to do this, but being a dumb C programmer it seems to me that that would be a good way to do it. Can you guys tell me how to do it correctly both in Peter/Ian and Dan's approaches? (basically, I'm probing for a realistic use case to get this right - obviously a number from 1-28 can be easily handled as a sequence, but I worry about having to enumerate numbers in the trillions) thanks JH Prof. James Hendler hendler@cs.umd.edu Computer Science Dept 703-696-2238 (phone) Univ of Maryland 703-696-2201 (Fax) College Park, MD 20853 http://www.cs.umd.edu/~hendler
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