How is the knowledge in an expert system acquired?

By knowledge engineering: interviewing practitioners, observing their decisions and turning their reasoning into rules the system can apply.

Why is the inference engine kept separate from the knowledge base?

The reasoning mechanism can then be reused for a different field simply by replacing the rules, and the rules can be revised without touching the program.

What is an explanation facility?

The part of the system that shows which rules led to its conclusion, so a user can judge whether to accept it.

Why is the explanation facility important in professional use?

A professional remains responsible for the decision, so an unjustified conclusion cannot safely be acted on.

WJEC A-Level Computer Science 601-5345-3

Hardware: Architecture, Memory and Storage

Topic overview Components of a computer system and how they connect Von Neumann architecture and the CPU The fetch-execute cycle Memory and caching Parallel processing Input and output devices and their uses Secondary storage, fragmentation and defragmentation

Networks and Data Transmission

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Logic Gates and Boolean Algebra

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Data Representation and Data Types

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Data Structures

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Organisation of Data: Files and Records

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Database Systems

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The Operating System

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Algorithms and Programs

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Principles of Programming

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Systems Analysis

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Types of Software System

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Practical Programming

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Data Security and Integrity

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Computing, Society and the Law

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Advanced Data Structures and Logic

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Programming Paradigms and Translators

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System Design and Human-Computer Interaction

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Software Engineering Tools and Professional Practice

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Advanced Architecture and Assembly Language

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Communication Networks and File Organisation

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Number Representation and Floating Point

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Databases and Distributed Systems

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Operating System Management

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Software Systems and Applications

Topic overview The range of software system types Safety related and safety critical systems Computer control and automation The scope of automation in practice Expert systems The internet, intranets and search Selecting and evaluating a software system

Data Security, Cryptography and Attack

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Software Systems and Applications

Expert systems

3 things to know
A2 Unit 4

Overview

Three main components of an expert system, explanation facility and balanced conclusion about expert systems in a profession.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

How is an expert system's knowledge obtained, why is it kept apart from the reasoning, and what justifies a conclusion?

Key term

What distinguishes an expert system from a database of information?

Key term

Name the three main components of an expert system.

Questions from this subtopic

Each one with the model answer underneath.

1
What distinguishes an expert system from a database of information?
Model answer
A database returns what is stored, whereas an expert system applies rules to the facts of a case to derive a conclusion that is not stored anywhere.
2
Name the three main components of an expert system.
Model answer
The knowledge base, the inference engine and the user interface.
3
How is the knowledge in an expert system acquired?
Model answer
By knowledge engineering: interviewing practitioners, observing their decisions and turning their reasoning into rules the system can apply.
4
Why is the inference engine kept separate from the knowledge base?
Model answer
The reasoning mechanism can then be reused for a different field simply by replacing the rules, and the rules can be revised without touching the program.
5
What is an explanation facility?
Model answer
The part of the system that shows which rules led to its conclusion, so a user can judge whether to accept it.
6
Why is the explanation facility important in professional use?
Model answer
A professional remains responsible for the decision, so an unjustified conclusion cannot safely be acted on.

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