cs62s: expert systems based on: the engineering of knowledge-based systems: theory and practice a....
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CS62S: Expert Systems
Based on:
The Engineering of Knowledge-based Systems: Theory and PracticeA. J. Gonzalez and D. D. Dankel
Introduction to Knowledge-based Systems
General problem solving knowledge Intelligent program
Inference engine Knowledge base Data / Fact base
Separation of knowledge from its use
For a new problem domain – change knowledge base
Knowledge Representation
Logic Rules Associative (semantic) networks Frames Objects
Traditional Computer Programming
Structured sequence of steps
Algorithm
Finite amount of time
Search – alternative to algorithmic solution
Path connecting problem to the solution
Problem space Procedurally defined Network Tree
Solution space (problem space examined)
Search Methods
Random
Blind
Directed
Search Types
Depth-first Breath-first Beam Hill-climbing Branch and bound Best-first A* (best-first and branch and bound)
Heuristics vs. algorithm
Specific knowledge Rule of thumb Prior knowledge Expertise Timely solution Estimation
Gonzalez and Dankel describes knowledge-based systems as:
“A computerized system that uses knowledge about some domain to arrive at a solution to a problem from that domain. This solution is essentially the same as that concluded by a person knowledgeable about the domain of the problem when confronted with the same problem“
Expert systems
Separation of knowledge from how it is used
Use of highly specific domain knowledge
Heuristic rather than algorithms
MYCIN
Used to diagnose blood disorderIncorporates all three elements
Types of expertise
Associational
The internal workings of a system are not understood. The behaviour is used to solve problems
Motor skills expertise
Practice makes perfect (sports, physical tasks, etc)
Theoretical expertise
The internal workings of a device or system are well understood. The expert can solve problems never seen before.
Advantages of Expert Systems
Wide distribution of scarce expertise Ease of modification Consistency of answers Perpetual accessibility Preservation of expertise Solution of Problem involving
incomplete data Explanation of solution
Disadvantages
Answers may not always be correct
Knowledge limited to the domain of expertise
Lack of common sense
Expert systems architecture
User
Knowledge engineer
Tool builder