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CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

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Page 1: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

CS62S: Expert Systems

Based on:

The Engineering of Knowledge-based Systems: Theory and PracticeA. J. Gonzalez and D. D. Dankel

Page 2: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. 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

Page 3: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Knowledge Representation

Logic Rules Associative (semantic) networks Frames Objects

Page 4: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Traditional Computer Programming

Structured sequence of steps

Algorithm

Finite amount of time

Page 5: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Search – alternative to algorithmic solution

Path connecting problem to the solution

Problem space Procedurally defined Network Tree

Solution space (problem space examined)

Page 6: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Search Methods

Random

Blind

Directed

Page 7: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Search Types

Depth-first Breath-first Beam Hill-climbing Branch and bound Best-first A* (best-first and branch and bound)

Page 8: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Heuristics vs. algorithm

Specific knowledge Rule of thumb Prior knowledge Expertise Timely solution Estimation

Page 9: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

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“

Page 10: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Expert systems

Separation of knowledge from how it is used

Use of highly specific domain knowledge

Heuristic rather than algorithms

Page 11: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

MYCIN

Used to diagnose blood disorderIncorporates all three elements

Page 12: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Types of expertise

Associational

The internal workings of a system are not understood. The behaviour is used to solve problems

Page 13: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Motor skills expertise

Practice makes perfect (sports, physical tasks, etc)

Page 14: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Theoretical expertise

The internal workings of a device or system are well understood. The expert can solve problems never seen before.

Page 15: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

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

Page 16: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Disadvantages

Answers may not always be correct

Knowledge limited to the domain of expertise

Lack of common sense

Page 17: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel

Expert systems architecture

User

Knowledge engineer

Tool builder

Page 18: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel
Page 19: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel
Page 20: CS62S: Expert Systems Based on: The Engineering of Knowledge-based Systems: Theory and Practice A. J. Gonzalez and D. D. Dankel