Expert system

Expert system are computer based systems that make use of wide range of human knowledge on a specific topic to solve various problems

Sometimes they can replace a human expert.

Components of an Expert System

1. Knowledge Base

Experts systems gather the knowledge of experts to form a knowledge base. 
In order to create an expert system it is necessary to employ a knowledge engineer.
He collects information and knowledge from subject specialists based on their experience.
He also gathers data from databases that exists for the topic.
This process is referred to as data mining.

2. Rules Base

Rule base is a set of rules which an inference engine uses, together with the data in the knowledge base.

3. Inference Engine

Inference engine is an important aspect to be designed to create an expert system
This is the reasoning part of the system

4. User Interface

The other important feature of an expert system is user interface
This is how the computer interacts with the user
It displays questions and information on the screen and enable the user to type the answer.

5. Shell

Shell include user interface, explanation system, inference engine and knowledge base editor.
Knowledge base editor software that enables the knowledge engineer to edit rules and facts within the knowledge base.

Applications of Expert system

1. Mineral Prospecting

Used to explore geological sites for the likelihood of a particular ore being found.
Expert system gathers input from sensors, satellite data or input from an expert.
System is used to calculate the probability of finding a particular ore.
By comparing the input values with models of similar areas.
The information required by the system is the geological make-up of the area.

2. Investment analysis

Used to monitor stock markets by looking at how prices of the various stocks vary.
Huge knowledge bases containing fats about prices of many stocks over years are kept
Then expert system can suggest possible trends.
This system is used by investment companies to decide the companies they should put their money into.

3. Tax Calculation

Many countries require their citizen to complete their own tax form
Expert system is used to calculate how much tax they have to pay.
System ask questions about:
– Their income
– Number of children they have
– Savings they have
– Pension contribution they make
– How old they are
- Whether a resident or non-resident

4. Route scheduling for delivery vehicles

This expert system calculate most efficient route for delivery vehicles.
The city map is input to the system then it outputs the shortest route for the vehicle to visit all the delivery points.
Typical services are postal service delivery, courier companies and travelling salesmen
Inputs required are:

–Number of drop off points
–Distance between each points
–Type and speed of vehicle used
–The lay out of the area being delivered (mountainous or flat)

5. Plant and Animal identification

User is asked about the features of the species of plant or animal
From the responses expert system can suggest the likely plant or animal.
System might ask;
–Does it eat meat?
–Does it live on land?
–Does it have vertebral column?
–Does it have a long neck?
–Does it have four legs?

6. Medical Diagnosis

Used by doctors, also allows patients to type in their symptoms and then generate possible illness.
It can’t replace a doctor but it acts in a consultative role.
Medical expert system is the largest of all expert systems, because there are incredible number of facts and rules that are always varying.

Advantages of Expert systems

  1. Expert systems provide accurate answers
  2. They never forget a fact or to ask a question.
  3. Can store more information than a human expert.
  4. Service is available round the clocklonger service period than a human expert

Disadvantages of Expert system

  1. It lacks common sense in some of the decision making situations
  2. Errors in the knowledge base can lead to incorrect advises being given
  3. Cannot adapt to changing situation unless knowledge base is continually updated.
  4. It is expensive to set up an expert system


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