4 Showing off KR

Classic description rules are attached to concepts and fire on any individuals of that concept that pass a filter. This rule is attached to event-or-object, and the filter insures that the individual has an information-item. When the rule fires, it returns the parents below represented-thing of the information item, and adds these to the parents of the event-or-object.

Note that the converse of this rule does not work, an information item can not be assumed to be of the same type as the event or object it describes. A person, for example, may have many interests and thus be classified under several unrelated subjects, yet not all the web pages associated with that person will describe all those subjects.

The utility of this rule can probably only be realized in practise. The work of populating the knowledge-base with individuals is triggered by discovering interesting web pages and other on-line information. When discovered, the appropriate information items and views are created, and placed in the represented-thing taxonomy. Especially in the case where a new information item describes an object or event that already exists in the knowledge-base, new subject information is typically not added to the object or event (for no other reason than that it is usually overlooked by the person doing it). This automated assistance then helps keep the knowledge-base more accurate.

There are basically two kinds of these rules:

* Good places to start a search. The ontology supports an understanding that certain web sites, such as Yahoo in general, or others that are more domain-specific, are good places to start a search.

* How to construct an address. Most expert web navigators fall back on several simple rules about where web servers might be. For example, if you are looking for information about a college, try www.college.edu. This may seem inherently obvious to some, but based on experience at Vassar this useful piece of knowledge is not very widespread.

Classic provides a powerful and flexible language for describing the sufficient conditions for subsumption. In other words, part of a concept description can be the sufficient conditions for classifying an individual under it. We intend to study how this can be used in conjunction with a web crawler (a program that follows links around the web) to automatically populate the knowledge-base.

This effort is not as far-fetched as it may seem. The development of HTML is moving towards providing more meta-information in the language, and encouraging HTML developers to make use of it. This meta-information can be of tremendous use in a system capable of doing inference.

The more you know about what you are looking for, the more information that is provided in the query, the faster it goes. The ontology was specifically designed to help a user find previously seen web pages or papers with only a vague recollection of what they were.

Here are some example queries supported by the ontology, and their accompanying translations into Classic:

* "Find all the AI Conference pages"

(and information-item
     (all information-item-of
          (and conference ai-thing)))

(and home-page 
     (all information-item-of 
          (and person ai-thing)))

(and home-page
     (all information-item-of
          (and person ai-thing
               (all employee-of company))))

(and paper ai-thing
     (at-least 1 has-document-text))

(and paper 
  (at-least 1 has-document-text)
  (fills year-published 1996)
  (all published-in 
       (all proceedings-of
            (fills name "FLAIRS-96"))))