CS6659 Artificial Intelligence
Topic: Expert Systems
III YEAR VI SEM
Presented by,
Ms. M. Rupa
, AP/CSE,JCTCET
Motivation & Objectives
• Utilization of computers to deal with knowledge
• Quantity of knowledge increases rapidly
• Knowledge might get lost if not captures
• Computers have special requirements for dealing
with knowledge
• Some knowledge related tasks can be solved better
by computers than by humans
INTRODUCTION
Expert systems are computer applications which embody
some non-algorithmic expertise for solving certain types of
problems.
For example :
• Diagnostic applications
• Play chess
• Financial planning decisions
• Configure computers
• Monitor real time systems
• Underwrite insurance policies
• Perform many services which previously required human
expertise.
What is Expert System ?
• An expert system, is an interactive computer-based
decision tool that uses both facts and heuristics to
solve difficult decision making problems, based on
knowledge acquired from an expert.
• Inference engine + Knowledge = Expert system
( Algorithm + Data structures = Program in
traditional computer )
• First expert system, called DENDRAL, was developed
in the early 65's at Stanford University.
Roles of Individuals who interact with
the system
• Domain expert : The individuals who currently are experts in
solving the problems; here the system is intended to
solve.
• Knowledge engineer : The individual who encodes the
expert's knowledge in a declarative form that can be used
by the expert system.
• User : The individual who will be consulting with the system
to get advice which would have been provided by the
expert.
• System engineer : builds the user interface, designs the
declarative format of the knowledge base, and implements
the inference engine.
Three Major ES Components
User Interface
Inference
Engine
Knowledge
Base
Components and Interfaces
• User interface : The code that controls the
dialog between the user and the system.
• Inference engine : The code at the core of the
system which derives recommendations from
the knowledge base and problem specific data
in working storage.
• Knowledge base : A declarative representation
of the expertise often in IF THEN rules .
Expert System Benefits
Benefits of Expert Systems
Availability − They are easily available due to mass
production of software.
Less Production Cost − Production cost is
reasonable. This makes them affordable.
Speed − They offer great speed. They reduce the
amount of work an individual puts in.
Less Error Rate − Error rate is low as compared to
human errors.
Reducing Risk − They can work in the environment
dangerous to humans.
Steady response − They work steadily without
getting motional, tensed or fatigued.
Expert System Limitations
No technology can offer easy and complete solution.
Large systems are costly, require significant development
time, and computer resources.
ESs have their limitations which includes −
Limitations of the technology
Difficult knowledge acquisition
ES are difficult to maintain
High development costs
Applications of Expert System
Knowledge Acquisition
• Knowledge acquisition is the process of extracting,
structuring and organizing knowledge from one source,
usually human experts, so it can be used in software
such as an ES.
Typical expert systems
Typical expert systems
MYCIN was an early backward chaining expert system that used
artificial intelligence to identify bacteria causing severe infections. It is used in
medical field.
DART
DART: Expert systems for automated computer fault diagnosis.
The Dynamic Analysis and Replanning Tool, explores the
application of artificial intelligence techniques to the diagnosis of
computer faults. It assists a technician in finding the faults in a
computer system. (hardware and software).
DART uses a device-independent language for describing devices
and device-independent inference procedure for diagnosis.
The primary goal of the DART Project is to develop programs that
capture the special design knowledge and diagnostic abilities of
these experts and to make them available to field engineers.
XCON
• XCON – (eXpert CONfigure) is a type of computer program used by
VAX – ("virtual address extension") or (logical address) Computers for
selecting various components based on customers requirements.
Expert System Shells
Shells − A shell is nothing but an expert system without knowledge
base.
A shell provides the developers with knowledge acquisition,
inference engine, user interface, and explanation facility.
A shell is a piece of software which contains the user interface, a
format for declarative knowledge in the knowledge base, and an
inference engine.
Many expert systems are built with products called expert system
shells.
The knowledge and system engineers uses these shells in making
expert systems.
• Knowledge engineer : uses the shell to build a system for
a particular problem domain.
• System engineer : builds the user interface, designs the
declarative format of the knowledge base, and
implements the inference engine.
Depending on the size of the system, the knowledge
engineer and the system engineer might be the same
person.
Outcome of Human Expert Behaviors in ES
• Recognize and formulate the problem
• Solve problems quickly and properly
• Explain the solution
• Learn from experience
• Restructure knowledge
• Break rules
• Determine relevance
• Degrade gracefully
