Hierarchically arranged knowledge domains

Details Hierarchically arranged knowledge domains Hierarchically arranged knowledge domains

1999-02-22

2001-06-12

Davis, George B. (Department: 2122)

Data processing: artificial intelligence

Knowledge processing system

Knowledge representation and reasoning technique

C706S047000

Reexamination Certificate

active

06247007

ABSTRACT:

TECHNICAL FIELD
This invention relates to expert systems, and more specifically, to a hierarchically arranged system of rules which provide an efficient method for operating on various objects, where such objects may be indeterminent at the time such rules are written.
BACKGROUND OF THE INVENTION
Recently, expert systems have come into use in the management and operation of large computer and other systems. Such expert Systems typically rely upon a plurality of rules which are applied to make decisions about the operation of the system intended to be governed by the rules.
One problem with such systems is that they are typically application specific, or, if not totally application specific, are intertwined with the particular application so much that portability and/or modification is problematic. Thus, while an expert system can be written to govern a particular set of circumstances, any time a new problem arises which an operator desires to control via the expert system, the system must be substantially modified and often totally rewritten in order to be ported to a new application. Even slight modifications to the existing application often require substantial reworking of the entire expert system.
One prior art reference which is directed to rules organized in an expert system hierarchy is U.S. Pat. No. 5,619,621 to Puckett. The '621 patent includes a plurality of rules which are broken down into sets and subsets and sub-subsets, and also provides a technique for executing the rules in an appropriate order. The rules are intended, in the main exemplary embodiment, to diagnose faults and other problems in an automated data storage system. The hierarchial set of rules is organized to correspond with a hierarchy of potential problems within this system. Thus, the highest level of rules in the hierarchy determines which of a plurality of high level data storage modules have malfunctioned. If so, the next level of rules determines what particular sub-portion of the module caused the malfunction. Each level in the hierarchy operates upon facts returned by a rule executed at the next higher level of the hierarchy.
The arrangement of the rules in such a manner allows for efficient application of the rules to various different problems which may arise with the system under consideration. The rules however, can only operate upon specified objects, namely, a database record in a particular format. Thus, if the structure of the database record is changed, or the knowledge system is to be applied in a totally different application, the whole system must be substantially rewritten.
Additionally, the rules at each level of the hierarchy are not restricted at all. Specifically, the rules operate on all types of data returned from other rules, and cause various activities to take place in response to such rules. Accordingly, minor changes in the databases or the system require that most of the software implementing the system be rewritten.
Moreover, in the '621 patent, no attempt has been made to provide for portable expert systems which are usable across a variety of fields of endeavor. Additionally, in certain applications, the data upon which the rules will operate will not actually exist until after such rules are already coded and compiled. Thus, it would be difficult to write a set of rules which apply to data items that have not yet in fact been-created. The teaching of the '621 patent provides no solution to this problem.
Additionally, it is always desirable for any rule based expert system to learn from experience as the system operates. Ideally, the system should learn from as many different sources as possible. The '621 patent provides a single and permanent rule base which does not change or update itself.
Another issue not addressed by the '621 patent relates to the formation of the rules themselves. Specifically, there are no safeguards built into the rule set to ensure the proper hierarchical structure of the rule set is preserved.
Recently, object orientated programming has become a preferred technique for implementing systems. In object oriented programming, objects are passed to different software routines, and the software operates upon the object.
Objects, for purposes of explanation herein, are anything that have a set of attributes and to which rules can be applied. For example, a database query is an object. A file is an object.
Objects are organized into domains, with objects having common attributes, regardless of the values of such attributes, being classified into a common domain. Objects in a domain may have numerous attributes which differ, as long as they all have the common subset of attributes required to meet the definition of the domain. Each domain of objects may have subdomains, and each subdomain may have further subdomains.
There are no known rule based systems for easily operating on objects of different types and which may be easily ported to other applications. Additionally, although object oriented systems can provide a technique for each object to identify itself as a particular type of object, there are no known rule based systems that take advantage of this fact.
SUMMARY OF THE INVENTION
The above and other problems of the prior art are overcome in accordance with the present invention which relates to a novel technique of organizing, structuring, applying, and updating rules in a knowledge system such that the rules are simplistic, portable, and efficiently applied to a variety of objects, one or more of which may be unknown at the time such rules are initially put into place.
In accordance with the invention, the rules are organized into a hierarchical structure and a variety of objects may be passed to the rules at the highest levels of the hierarchy. The highest level of the hierarchy includes one or more domains. A domain may have objects passed to it whether or not the rules from that domain are to be applied to such objects.
Before a rule in a domain executes, the domain first determines if the object which has been passed to such rule is an object type to which rules in the domain apply. If not, the object is said to be not within the “domain” of the rule. In such a situation, rules at any level below such rule in the hierarchy are not to be executed, and thus efficiency is maximized by automatically concluding that any rule related to such rule is inapplicable to such an object.
Every object passed to any domain of rules is first interrogated to determine what type of object it is. This can be accomplished with features included in modern object oriented languages. If the object is not of the type to which rules in the particular domain apply, or if the object does not identify itself as being of any particular type, then the rules are simply not applied. Thus, if objects are added after the system has been built, the system need not be substantially rewritten. Rather, the domains will simply determine that the new objects do or do not fall within their respective domains, and thus, the rules will or will not, respectively, be applied to such domains.
The hierarchy of domains is organized so that as the hierarchy is traversed, each level differs by the minimum possible amount. Thus, the domains proceed, for example, from a database to a, record to a field, not from a database to a field.


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Cardiff, J.P., “The Use of Integrity Constraints to Perform Query Transformations in Relational Databases”, IEEE International

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