Page 187 - DCAP506_ARTIFICIAL_INTELLIGENCE

Unit 13: Expert Systems and its Architecture

is described in detail in these applications. The first action taken is to obtain values for all Notes
evidence nodes which have been assigned an “initial” attribute. Using only the answers to these
initial evidences, the rules are ordered so that the most likely to succeed is evaluated first. The
trees can be further reordered since they are constantly being updated as a selected tree is being
traced.
It has been found that the type of information that is solicited by the system from the user by
means of questions or classes should be tailored to the level of knowledge of the user. In many
applications, the group of prospective uses is nicely defined and the knowledge level can be
estimated so that the questions can be presented at a level which corresponds generally to the
average user. However, in other applications, knowledge of the specific domain of the expert
system might vary considerably among the group of prospective users.

One application where this is particularly true involves the use of an expert system, operating in
a self-diagnostic mode on a personal computer to assist the operator of the personal computer to
diagnose the cause of a fault or error in either the hardware or software. In general, asking the
operator for information is the most straightforward way for the expert system to gather
information assuming, of course, that the information is or should be within the operator’s
understanding.

Example: In diagnosing a personal computer, the expert system must know the major
functional components of the system. It could ask the operator, for instance, if the display is a
monochrome or color display. The operator should, in all probability, be able to provide the
correct answer 100% of the time. The expert system could, on the other hand, cause a test unit to
be run to determine the type of display. The accuracy of the data collected by either approach in
this instance probably would not be that different so the knowledge engineer could employ
either approach without affecting the accuracy of the diagnosis.
However, in many instances, because of the nature of the information being solicited, it is better
to obtain the information from the system rather than asking the operator, because the accuracy
of the data supplied by the operator is so low that the system could not effectively process it to
a meaningful conclusion.
In many situations the information is already in the system, in a form of which permits the
correct answer to a question to be obtained through a process of inductive or deductive reasoning.
The data previously collected by the system could be answers provided by the user to less
complex questions that were asked for a different reason or results returned from test units that
were previously run.

Task Illustrate the concept of Procedure Node Interface.
13.3.5 User Interface

The function of the user interface is to present questions and information to the user and supply
the user’s responses to the inference engine. Some responses are restricted to a set of possible
legal answers, others are not. The user interface checks all responses to insure that they are of the
correct data type. Any responses that are restricted to a legal set of answers are compared against
these legal answers. Whenever the user enters an illegal answer, the user interface informs the
user that his answer was invalid and prompts him to correct it.

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