Explain What is Meant by an Expert System and Describe its Components and

Applications

What is an Expert System?

• An Expert System is also known as a Knowledge Based System (KBS).

• It is a computer programme made up of knowledge and rules that can be used to diagnose a problem.

• It is called an Expert System because the knowledge and rules are defined by experts in their field.

• The system will try and replicate the role of a human expert.

NHS Example

• A popular expert system is that used by NHS Direct on their website.

• Experts (doctors) have collated all their knowledge about illness and the symptoms of those illnesses and identified the rules that state which symptoms suggest which illness.

Expert System

• A true expert system will:– Be able to make decisions based on uncertain data.

(e.g. ‘don’t know’ answers from users).– Be limited to a particular subject or area of expertise.– Give advice based on the answers given by the user.– Explain the reasoning behind its decision.

Components of an Expert System

• There are three main components in an expert system:– A knowledge base– An inference engine– User interface

Knowledge Base

• Knowledge base consists of the factual knowledge and the rules gathered by knowledge engineers using methods such as interviewing experts.

• Examples of knowledge are:– The VAT rate is 17.5%– A mobile phone needs a

battery or power to work– A human has two hands

Rules

• Example of rules include:– If the product is food then VAT should not be applied.– If the battery is not inserted the phone will not turn on.– If the phone is plugged in the phone should turn on.– If a patient has a cut on their hand and the bleeding

can be controlled by putting a finger on the cut.

Inference Engine

• The inference engine is the software that makes the decisions based on the answers given by the user and the knowledge and rules stored in the knowledge base.

• It bases the next question on the answer given.

• If the answer is uncertain then it will ask more questions.

Inference Engine

User Interface

• The user interface is the part of the expert system that asks the user the questions and then gives an answer with a diagnosis.

• An example of this is the NHS Direct Self-Help where questions are being asked about what type of ailment the

person has.

Microsoft Office User Interface

Applications of Expert Systems

• Here are some examples of how expert systems might be used:– Fault diagnosis for a car

engine – car mechanic can plug in a laptop computer into the engine management system and it will run various tests,

– Based on the results of the tests, it will identify what the fault is with the engine.

• Broadband Internet Service Provider (ISP) fault diagnosis.

• When you call your ISP to report a fault the operator is likely to be using an expert system.

• The operator will ask you questions that the expert system tells them to ask.

• The expert system will then suggest possible solutions that could be tried out.

Applications of Expert Systems

• Social Services can use expert systems to determine what benefits are due to a claimant.

• All the answers that the claimant puts on the forms are input into a computer and the expert system will then determine the benefits.

• It will also give a reason why those benefits apply.

Applications of Expert Systems

Jobseekers Allowance

The advantages and disadvantages for a given application

Think about the example and be able to look at the advantages (Remote access, frees up human time, logic and modelling of what if scenarios) Vs. the disadvantages (GIGO, Human knowledge could be incorrect, irrelevant, not timely, IT systems could crash, the interface may confuse people etc etc)

Questions

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