​LEARNING OBJECTIVES

• Identify a range of applications which use expert systems​

• Identify the components of an expert system

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• Expert systems have been developed to mimic the expertise and knowledge of an expert in a particular field

• Knowledge from human experts is entered into the system and stored

• People using the expert system can then question it (query) and access this stored knowledge

• The system searches it's stored data for anything that provides an answer to the information that a user has input​

EXPERT SYSTEM

• prospecting for oil and minerals

• diagnostics (finding faults in a car engine, finding faults on a circuit board, etc.)

• medical diagnosis

• strategy games (e.g. chess)

EXAMPLES

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• tax and financial planning

• route scheduling for delivery vehicles

• identification of plants, animals and chemical compounds

EXAMPLES

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• They offer a high level of expertise.

• They offer high accuracy.

• The results are consistent.

• They have the ability to store vast amounts of ideas and facts.

• They can make traceable logical solutions and diagnostics.

ADVANTAGES

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• It is possible for an expert system to have multiple types of expertise.

• They offer a very fast response time (much quicker than a human expert).

• They provide unbiased reporting and analysis of the facts.

• They indicate the probability of any suggested solution being correct.

ADVANTAGES

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• Users of the expert system need considerable training in its use to ensure the system is being used correctly.

• The set-up and maintenance costs are very high.

• They tend to give very ‘cold’ responses which may not be appropriate in certain medical situations.

DISADVANTAGES

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• They are only as good as the information/facts entered into the system.

• Users sometimes make the very dangerous assumption that they are infallible.

DISADVANTAGES

STRUCTURE OF EXPERT SYSTEM

USER INTERFACE​

• This is the method by which the expert system interacts with a user.

• It allows interaction through dialogue boxes, command prompts or other input methods.

• The questions being asked usually only have yes/no answers and are based on the responses to previous questions.

EXPLANATION SYSTEM

• This informs the user of the reasoning behind the expert system’s conclusions and recommended actions.

• For example, suppose the user was investigating a series of symptoms in a patient and the expert system gave the diagnosis of mercury poisoning; the explanation system would explain its reasoning with a statement such as ‘impaired vision, lack of coordination, weak muscles, slurred speech and the

  patient used to work in a paint factory’. The user could then probe deeper if necessary.

INFERENCE ENGINE

• This is the main processing element of the expert system.

• The inference engine acts like a search engine examining the knowledge base for information/data that matches the queries.

• It is responsible for gathering information from the user by asking a series of questions and applying responses where necessary; each question being asked is based on the previous responses.

INFERENCE ENGINE

• The inference engine is the problem-solving part of the expert system, which makes use of inference rules in the rules base.

• Because the knowledge base is a collection of objects and attributes, the inference engine attempts to use information gathered from the user to find an object that matches (making use of the rules base to find a match).

KNOWLEDGE BASE

• The knowledge base is a repository of facts.

• It stores all the knowledge about an area of expertise obtained from a number of expert resources.

• It is basically a collection of objects and their attributes

KNOWLEDGE BASE

• Is it a mammal? YES

• Does it live in water? YES

• Does it make sonic sounds? YES

• Is its body covered in skin? YES

• Does it have any legs? NO

RULES BASE

• The rules base is a set of inference rules.

• Inference rules are used by the inference engine to draw conclusions (the methods used closely follow human reasoning).

• They follow logical thinking like the example above; usually involving a series of ‘IF’ statements, for example:

  IF continent = ‘South America’ AND language = ‘Portuguese’ THEN country = ‘Brazil’.

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