Expert Systems (Cambridge International IGCSE ICT)
Spec point —
6.8.1
Expert Systems
What is an expert system?
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An expert system mimics human knowledge and experience and uses a combination of the two to solve problems or answer questions
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Examples of expert systems include:
- Equipment troubleshooting and repair
- Technical support
- Medical diagnosis system
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Expert systems share five key characteristics
| Knowledge base | - A database of facts to generate rules that are used to solve problems and make decisions |
|---|---|
| Rule base | - A set of rules or logic that is used to apply the knowledge in the knowledge base to specific problems |
| Inference engine | - A program that applies the rules in the rule base to the facts in the knowledge base to solve problems |
| Interface | - A way for users to interact with the system and provide input |
| Explanation system | - Provides the users with explanation and reasoning behind decisions or recommendations - Gives a percentage probability of the accuracy of its conclusions |
Case Study Movie recommendation system
Inputs
- Indicate favourite genres/directors
- Rate movies watched (stars/thumbs up, thumbs down etc.)
- Previous movie searches (keywords)
Inference engine
- Matching similar movies to users history (based on director/genre/actor/reviews etc.)
- Filtering movies with similar characteristics as previously watched
- Filtering movies based on what users with similar tastes have watched/liked
Output
- Display a personalised list of movie recommendations
Advantages and disadvantages of expert systems
| Advantages | Disadvantages |
|---|---|
| - Consistent results - Faster responses - Can store large amounts of data - Unbiased | - Only as good as the data entered - Responses can be cold and lack human emotion - Requires training to use correctly |
Worked Example Expert systems are used by doctors. a. Describe how an expert system can be used to diagnose illnesses.
[5]
b. Name two other applications of expert systems.
[2]
Answers
a. five of:
Final answer: An Interactive user interface appears [1] Questions are asked about the illness [1] Yes and No type answers to the questions [1] Answers lead to other questions [1] The inference engine searches the knowledge base [2] Using the rules base [1] Probabilities/possibilities of diagnoses and treatments are displayed [1] Displays the ways it achieved the solutions/conclusions / explanation [1]
b. two of:
Final answer: Mineral prospecting [1] Car engine fault diagnosis [1] Chess games [1] Tax queries [1] Careers recommendations [1] Movie recommendations on streaming platforms [1]
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