Page 184 - DCAP506_ARTIFICIAL_INTELLIGENCE

Artificial Intelligence

Notes A. No
Q. Is there any kind of food you would particularly like?
A. No
Q. Do you like spicy food?

A. No
Q. Do you usually drink wine with meals?
A. Yes
Q. When you drink wine, is it French wine?

A. Yes
As can be seen from this dialog, the system is leading the user through a set of questions, the
purpose of which is to determine a suitable set of restaurants to recommend. This dialog begins
with the system asking if the user already knows the restaurant choice (a common feature of
expert systems) and immediately illustrates a characteristic of expert systems; users may choose
not to respond to any question.
In expert systems, dialogs are not pre-planned. There is no fixed control structure. Dialogs are
synthesized from the current information and the contents of the knowledge base. Because of
this, not being able to supply the answer to a particular question does not stop the consultation.

13.3.2 Explanation System (Another Part of Expert System)

Another major distinction between expert systems and traditional systems is illustrated by the
following answer given by the system when the user answers a question with another question,
“Why”, as occurred in the above example. The answer is:
A. I am trying to determine the type of restaurant to suggest. So far Chinese is not a likely choice.
It is possible that French is a likely choice. I know that if the diner is a wine drinker, and the
preferred wine is French, then there is strong evidence that the restaurant choice should include
French. It is very difficult to implement a general explanation system (answering questions like
“Why” and “How”) in a traditional computer program. An expert system can generate an
explanation by retracing the steps of its reasoning. The response of the expert system to the
question WHY is an exposure of the underlying knowledge structure. It is a rule; a set of
antecedent conditions which, if true, allow the assertion of a consequent. The rule references
values, and tests them against various constraints or asserts constraints onto them. This, in fact,
is a significant part of the knowledge structure. There are values, which may be associated with
some organizing entity.

Example: The individual diner is an entity with various attributes (values) including
whether they drink wine and the kind of wine.
There are also rules, which associate the currently known values of some attributes with assertions
that can be made about other attributes. It is the orderly processing of these rules that dictates
the dialog itself.

13.3.3 Expert Systems versus Problem-solving Systems

The principal distinction between expert systems and traditional problem solving programs is
the way in which the problem related expertise is coded. In traditional applications, problem

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