Expert systems Cambridge IGCSE Information & Communication Technology revision
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In plain words
A good doctor or mechanic carries years of knowledge in their head. An expert system is an attempt to put that knowledge into a computer, so that it can ask the right questions and suggest an answer, for anyone, at any time.
6 things to know
- An expert system is software that mimics the knowledge and reasoning of a human expert in one subject.
- Uses: medical diagnosis, car engine fault diagnosis, mineral prospecting, financial planning, chess, route scheduling for delivery vehicles, and identifying plants and animals.
- Its parts. The user interface asks the questions and shows the results. The knowledge base stores the facts. The rules base stores the rules that link the facts. The inference engine applies the rules to the facts to reach conclusions. The explanation system shows how a conclusion was reached.
- How it is used: the user answers questions on screen. The inference engine searches the knowledge base, using the rules. Possible solutions are displayed, often with a probability and an explanation.
- Advantages: it is always available, it gives consistent answers, it does not forget, and it brings expert knowledge to places with no expert.
- Disadvantages: it has no common sense, it is only as good as the knowledge put in, it is expensive to set up, and it must be kept up to date.
Worked example
A mechanic uses an expert system to find a fault in a car engine. Describe what happens.
- The system asks questions about the symptoms through the user interface, and the mechanic types or selects the answers.
- The inference engine searches the knowledge base, using the rules in the rules base to match the symptoms to faults.
- The possible faults are displayed, with how likely each one is, and the explanation system shows the reasoning.
Tips and tricks
- Five components in this syllabus: user interface, inference engine, knowledge base, rules base and explanation system.
- The inference engine does the reasoning. The knowledge base only stores facts.
It lands in your notebook with its questions as flashcards.
Expert systems: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What is an expert system?
It works in one subject area.
Which component stores the facts?
The rules are kept in the rules base.
Which component applies the rules to reach a conclusion?
It does the reasoning.
What does the explanation system do?
The user can see the reasoning.
Which is a disadvantage of an expert system?
It can only follow its rules.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
2 questions, 6 marks. Write your answers on paper, then check them.
Expert systems
Cambridge IGCSE Information & Communication Technology 0417 · 6 marks · papermunch.org
Name ______________________________ Date ______________
Name four components of an expert system.[4]
Show answerHide answer
The user interface, the knowledge base, the rules base and the inference engine. (Also: the explanation system.)
Give two advantages of using an expert system for medical diagnosis.[2]
Show answerHide answer
It is available at any time, even where there is no specialist. It gives consistent answers and does not forget anything.
Answers: Expert systems
- 1. The user interface, the knowledge base, the rules base and the inference engine. (Also: the explanation system.)
- 2. It is available at any time, even where there is no specialist. It gives consistent answers and does not forget anything.