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Overview of Expert Systems

- A collection of software packages and tools used to develop expert systems

Randy Trevor
Randy Trevor
May 17, 2010
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Can…

Explain their reasoning or suggested decisions
Display intelligent behavior
Draw conclusions from complex relationships
Provide portable knowledge

 

Expert system shell

A collection of software packages and tools used to develop expert systems

Expert System Functionality 

Replace human expert decision making when not available

Assist human expert when integrating various decisions

Provides an ES user with

      --an appropriate hypothesis

      --methodology for knowledge storage and reuse

Border field to Knowledge Based Systems, Knowledge Management

Knowledge intensive × connectionist

Expert system – software systems simulating expert-like decision making while keeping knowledge separate from the reasoning mechanism 

Limitations of Expert Systems
 
Not widely used or tested
Limited to relatively narrow problems
Cannot readily deal with “mixed” knowledge
Possibility of error
Cannot refine own knowledge base
Difficult to maintain
May have high development costs
Raise legal and ethical concerns

 

Expert Systems Classification

Unlike classical problem solver (GPS, Theorist) Expert Systems are weak, less general, very case specific
Expert systems classification:

-Interpretation
-Prediction
-Diagnostic
-Design & Configuration
-Planning
-Monitoring
-Repair & Debugging
-Instruction
-Control

Underlying Philosophy

Knowledge representation
   production rules
   logic
   semantic networks
   frames, scripts, objects

Reasoning mechanism
   knowledge-oriented reasoning
   model-based reasoning
   case-based reasonig

 

Knowledge Representation in ES

Shallow Knowledge Models

    rules, frames, logic, networks
    first generation expert systems

Deep Knowledge Models
    describes complete systems causality
    second generation expert systems

Case Knowledge Models
    specifies precedent in past decision making

  

Capabilities of Expert Systems

 

Explore impact of strategic goal

 

Impact of plans on resources

 

Integrate general design principles and manufacturing limitations

Provide advise on decisions

 

Monitor quality and assist in finding solutions

Look for causes and suggest solutions

 

When to Use an Expert System

1. Provide a high potential payoff or significantly reduced downside risk
2. Capture and preserve irreplaceable human expertise
3. Provide expertise needed at a number of locations at the same time or in a hostile environment

4.  Provide expertise that is expensive or rare
5. Develop a solution faster than human experts can
6. Provide expertise needed for training and development to share the wisdom of human experts with a large number of people that is dangerous to human health.

Components of an Expert System


Knowledge base
    Stores all relevant information, data, rules, cases, and relationships used by the expert system
Inference engine
    Seeks information and relationships from the knowledge base and provides answers, predictions, and suggestions in the way a human expert would
Rule
    A conditional statement that links given conditions to actions or outcomes

Fuzzy logic
    A specialty research area in computer science that allows shades of gray and does not require everything to be simply yes/no, or true/false
Backward chaining
    A method of reasoning that starts with conclusions and works backward to the supporting facts
Forward chaining
    A method of reasoning that starts with the facts and works forward to the conclusions
 

Expert System Architecture

 


 

 

 

 

 

 

 

 

 

 

 

 

 

Rules for a Credit Application

 

 

 

 

 

 

 

 

 

 

 

 

 

Explanation Facility

A part of the expert system that allows a user or decision maker to understand how the expert system arrived at certain conclusions or results 

 

Knowledge Acquisition Facility

Provides a convenient and efficient means of capturing and storing all components of the knowledge base

 

 

 

 

 

 

 

 

 

 

 

 

 

Expert Systems Development

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Participants in Expert Systems Development and Use

Domain expert
The individual or group whose expertise and knowledge is captured for use in an expert system

Knowledge user
The individual or group who uses and benefits from the expert system

Knowledge engineer
Someone trained or experienced in the design, development, implementation, and maintenance of an expert system

 

 

 

Expert System


 

 

 

 

 

 

 

 

 

 

 

 

 

 

Advantages of Expert Systems

Easy to develop and modify
The use of satisficing

The use of heuristics

Development by knowledge engineers and users
 
 
 
Applications of Expert Systems and Artificial Intelligence
 
•Credit granting
 
•Information management and retrieval
 
•AI and expert systems embedded in products
 
•Plant layout
 
•Hospitals and medical facilities
 
•Help desks and assistance
 
•Employee performance evaluation
 
•Loan analysis
 
•Virus detection
 
•Repair and maintenance
 
•Shipping
 
•Marketing
 
•Warehouse optimization

 

Author's note: Courtesy: Michal Pěchouček Gerstner Laboratory for Intelligent Decision Making and Control
Keywords: Expert Systems, decision , connectionist, Functionality, Expert system shell



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