Page 244 - DCAP310_INTRODUCTION_TO_ARTIFICIAL_INTELLIGENCE_AND_EXPERT_SYSTEMS

Introduction to Artificial Intelligence & Expert Systems

Notes
Figure 13.2: Expert System Shell
Expert System Shell

Explanation Case—
system
User specific
data
User
Interface Inference
engine
Knowledge
Knowledge base
base editor

One important feature of expert systems is the way they (usually) separate domain specific
knowledge from more general purpose reasoning and representation techniques. The general
purpose bit (in the dotted box in the figure) is referred to as an expert system shell. As we see in the
figure, the shell will provide the inference engine (and knowledge representation scheme), a
user interface, an explanation system and sometimes a knowledge base editor. Given a new
kind of problem to solve (say, car design), we can usually find a shell that provides the right sort
of support for that problem, so all we need to do is provide the expert knowledge. There are
numerous commercial expert system shells, each one appropriate for a slightly different range
of problems. (Expert systems work in industry includes both writing expert system shells and
writing expert systems using shells.)

!
Caution Using shells to write expert systems generally greatly reduces the cost and time
of development (compared with writing the expert system from scratch).

Self Assessment

State whether the following statements are true or false:

1. Expert systems typically contain the two components.
2. Expert system shells on microcomputers.
3. The user interface is the part of the program that interacts with the user.

13.2 Rule-based Systems

Conventional problem-solving computer programs make use of well-structured algorithms,
data structures, and crisp reasoning strategies to find solutions. For the difficult problems with
which expert systems are concerned, it may be more useful to employ heuristics: strategies that
often lead to the correct solution, but that also sometimes fail. Conventional rule-based expert
systems, use human expert knowledge to solve real-world problems that normally would
require human intelligence. Expert knowledge is often represented in the form of rules or as data
within the computer. Depending upon the problem requirement, these rules and data can be
recalled to solve problems. Rule-based expert systems have played an important role in modern
intelligent systems and their applications in strategic goal setting, planning, design, scheduling,
fault monitoring, diagnosis and so on. With the technological advances made in the last decade,
today’s users can choose from dozens of commercial software packages having friendly graphic
user interfaces (Ignizio, 1991).

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