Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!uunet!zephyr.ens.tek.com!uw-beaver!ubc-cs!alberta!naren From: naren@cs.UAlberta.CA (Narendra Ravi) Newsgroups: comp.object Subject: Re: Survey: how do we really use objects? Message-ID: Date: 3 Dec 90 08:01:37 GMT References: <2586@runxtsa.runx.oz.au> <47024@apple.Apple.COM> Sender: news@cs.UAlberta.CA (News Administrator) Organization: University of Alberta, Edmonton, Alberta, Canada Lines: 85 ksand@Apple.COM (Kent Sandvik) writes: >In article egdorf@zaphod.lanl.gov (Skip Egdorf) writes: >>In article <2586@runxtsa.runx.oz.au> timm@runxtsa.runx.oz.au (Tim Menzies) writes: >>> >>> Are inheritance hierarchies a good way you represent >>> knowlege? >>While some (as you point out, simple) hierarchies exist that capture some >>bits of knowledge, real knowledge-based systems require more complex >>representations than are available in object-oriented programming systems. >>While object-oriented programming systems can be used to capture such simple >>heirarchies, such use in real applications does not allow the capture of >>the more complex relationships. The object-oriented programming system >>captures the lower-level details of the construction of the higher-level >>knowledge-representation system (when properly used as am implementation >>tool.) Not always true. See below. >The objects are quite cabable of knowing knowledge about their internal >data and relationships between. But it is true that the OOPS paradigm >is not very well suitable for cross-knowledge. No, Not just the OOPS paradigm, but coupled with deduction it definitely is a good tool. See below. >If we look at multiple inheritance and knowledge inheritance, we still >have problems with definitions of relationships between objects. Yes, but addition of epistemic knowledge would definitely help. >Has anyone looked at providing meta-information in meta-objects that >have built-in methods for knowledge requisition, for example having >Prolog methods and fields embedded in meta-objects? The people working on the CYC project at MCC should be able to answer this question. The articles they publish definitely give an indication that they use inheritance hierarchies. But what exactly they use to enhance the usability/maintenance of information (even) at the meta-level is not very clear. They do talk of special inference procedures to manage large bodies of (non-programmer) knowledge. Here is a small quote ... it is likely that the new constructs (to CycL, the representation language) are going to be incrementally added to improve CycL's inferencing. ... such special purpose constructs (templates for classification, inheritance, special-purpose inference mechanisms, and so on) is likely to prove bothersome to other programs that use Cyc. The representation provides (according to the authors) a basis of epistemological and default reasoning. The paper I am referring to is the Midterm report on Cyc. Cyc: A Midterm Report: R. V. Guha, D. B. Lenat AI Magazine, Fall 1990. But this is not where actual technology is discussed. One gets only a flavor for what is happening. I have said enough. Now other enlightened people can provide a better analysis of the issue. >regards, >Kent Sandvik Cheers, Naren. -- ======================================================================= * Narendra Ravi * 615, General Services Building, * * Email : naren@cs.ualberta.ca * Department of Computing Science * * : naren@alberta.UUCP * University of Alberta * * Tel : (403) 492-3520 (Off) * Edmonton, Alberta, CANADA T6G 2H1 * ======================================================================= Brought to you by Super Global Mega Corp .com