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									Expert Systems
 An expert system is a computer
 program that is designed to hold
 the accumulated knowledge of
 one or more domain experts
Examples

 Diagnostic applications, servicing:
   People
   Machinery

 Play chess
 Make financial planning decisions
 Configure computers
 Monitor real time systems
 Underwrite insurance policies
 Perform many other services which previously
 required human expertise
Applications of Expert Systems
                                   PUFF:
                              Medical system
                              for diagnosis of
                           respiratory conditions




    PROSPECTOR:
   Used by geologists
   to identify sites for
    drilling or mining
Applications of Expert Systems
                               MYCIN:
                         Medical system for
                     diagnosing blood disorders.
                         First used in 1979




  DESIGN ADVISOR:
   Gives advice to
     designers of
   processor chips
Applications of Expert Systems
                          DENDRAL: Used to
                        identify the structure of
                         chemical compounds.
                           First used in 1965




LITHIAN: Gives advice
   to archaeologists
examining stone tools
Components of an Expert System

 The knowledge base is the collection of facts
 and rules which describe all the knowledge
 about the problem domain
 The inference engine is the part of the
 system that chooses which facts and rules to
 apply when trying to solve the user’s query
 The user interface is the part of the system
 which takes in the user’s query in a readable
 form and passes it to the inference engine. It
 then displays the results to the user.
Major Components

 Knowledge base - a declarative
 representation of the expertise, often in IF
 THEN rules
 Inference engine - the code at the core of
 the system
    Derives recommendations from the
     knowledge base and problem-specific data
     in working storage
 User interface - the code that controls the
 dialog between the user and the system
Why use Expert Systems?
 Experts are not always
 available. An expert
 system can be used
 anywhere, any time.
 Human experts are not
 100% reliable or consistent
 Experts may not be good at
 explaining decisions
 Cost effective
Major Roles of Individuals

 Domain expert – currently experts solving
 the problems the system is intended to solve
 Knowledge engineer - encodes the expert's
 knowledge in a declarative form that can be
 used by the expert system
 User - will be consulting with the system to
 get advice which would have been provided
 by the expert
 Systems built with custom developed shells
 for particular applications:
     System engineer - the individual who builds
      the user interface, designs the declarative
      format of the knowledge base, and implements
      the inference engine
Advantages and
Disadvantages
Advantages:
 Consistent answers for repetitive
 decisions, processes and tasks
 Holds and maintains significant levels of
 information
 Encourages organizations to clarify the
 logic of their decision-making
 Never "forgets" to ask a question, as a
 human might
Advantages and
Disadvantages
Disadvantages:
  Lacks common sense
  Cannot make creative responses as human
  expert
  Domain experts not always able to explain
  their logic and reasoning
  Errors may occur in the knowledge base
  Cannot adapt to changing environments
Problems with Expert Systems
  Limited domain
  Systems are not always
  up to date, and don’t
  learn
  No “common sense”
  Experts needed to setup
  and maintain system
Expert Systems on the Web
http://www.aiinc.ca/demos/whale.html
http://www.vanguardsw.com/
decisionscript/examples.htm
http://www.exsys.com/demomain.html
http://www.expertise2go.com/webesie/car
http://www.expertise2go.com/webesie/wine
FIN

								
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