timm@runxtsa.runx.oz.au (Tim Menzies) (11/28/90)
Are inheritance hierarchies a good way you represent knowlege? I recently presented a paper (by proxy, thanx Alan) to the 1990 Australian Joint Artificial Intelligence conference. In that, I observed that in the three years that I have been using OO tools for expert systems, I have **never** shown an object hierarchy to a expert. My own hierarchies were so intiricate, I ended up hiding them behind interfaces that presented some abstarcted/filtered view of networks of instances to the experts. One of the comments after the presentation was that hierachies **MUST BE** a good way of representing knowlege because of the all the real world knowledge represented as hierarchies. For example, in biology, the classification of plants and animals are all presented hierarchically. (I don't agree with this argument BTW, see below). Now, we could debate this issue, or we subject it to an emperical test. Could anyone who has actually built a non-trivial object system email me (or the net) and let me know how much of the explicit business/expert knowledge was clearly defined in an inheritance hierarchy? If there is enough interest in this, I'll post a reply. As to the above argument re plant/animal classification: Just what are those hierarchies used for? Actually expert processing of significant biologically problems? Or only as a learning tool for new biologists? (I suspect the latter.) My own experience has been that in order to make an inheritance hierarchy useful (in some non-trivial sense), then we need to surround/bury the hierarchy in such an intricate architecture that the significance/usefulness of the hierarchy reduces to zero. Hierarchies, I have found are useful for storing programmer knowledge, but not non- programmer expert knowledge. -- Tim Menzies (timm@runxtsa.oz) HiSoft Expert Systems Group, 2-6 Orion Rd Lane Cove, NSW, 2d066 02 9297729(voice),61 2 4280200(fax)