23-01-2013, 12:08 PM
Introduction to Expert Systems
Introduction to Expert.ppt (Size: 2.91 MB / Downloads: 53)
Objectives
Learn the meaning of an expert system
Understand the problem domain and knowledge domain
Learn the advantages of an expert system
Understand the stages in the development of an expert system
Examine the general characteristics of an expert system
Examine earlier expert systems which have given rise to today’s knowledge-based systems
Explore the applications of expert systems in use today
Examine the structure of a rule-based expert system
Learn the difference between procedural and nonprocedural paradigms
What are the characteristics of artificial neural systems
What is an expert system?
Emulation (mimics cause/process) is stronger than simulation (mimics outward appearance) which is required to act like the real thing in only some aspects.
The basic idea is that if a human expert can specify the steps of reasoning by which a problem may be solved, so too can an expert system.
Restricted domain expert systems (extensive use of specialized knowledge at the level of human expert) function well which is not the case of general-purpose problem solver.
Expert System Main Components
Knowledge base – obtainable from books, magazines, knowledgeable persons, etc; or expertise knowledge.
Inference engine – draws conclusions from the knowledge base.
Problem Domain vs. Knowledge Domain
In general, the first step in solving any problem is defining the problem area or domain to be solved.
An expert’s knowledge is specific to one problem domain – medicine, finance, science, engineering, etc.
The expert’s knowledge about solving specific problems is called the knowledge domain.
The problem domain is always a superset of the knowledge domain.
Expert system reasons from knowledge domain.
Advantages of Expert Systems
Increased availability: on suitable computer hardware
Reduced cost
Reduced danger: can be used in hazardous environment.
Permanence: last for ever, unlike human who may die, retire, quit.
Multiple expertise: several experts’ knowledge leads to
Increased reliability
The Role of AI
An algorithm is an ideal solution guaranteed to yield a solution in a finite amount of time.
When an algorithm is not available or is insufficient, we rely on artificial intelligence (AI).
Expert system relies on inference – we accept a “reasonable solution.”
Languages, Shells, and Tools
Expert system languages are post-third generation.
Expert system languages (e.g. CLIPS) focus on ways to represent knowledge.
Tool = language + utility program (code generator, graphics editor, debuggers, etc.).
Shell: is a special purpose tool designed for certain types of applications in which the user must supply the knowledge base. Example, EMYCIN (empty MYCIN)