Course Instructor:

Kashif Ihsan1

Chapter # 2

Kashif Ihsan, Lecturer CS, MIHE 2

ExpertDictionary Meaning:

A person with a status of an authority in a specific subject due to special skills, training or knowledge.

Other name for an expert is Specialist.

A person who has certain expertise or who has acquired skills from experience.

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Imagine ?Imagine a piece of software that runs on your

PC which provides the same sort of interaction and advice as a career counselor helping you decide what education field to go into and perhaps what course to pursue.

ORA piece of software which asks you questions

about your defective TV and provides a diagnosis about what is wrong with it. Such software, called expert systems, actually exist.

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Definition“An expert system is a computer system that

emulates, or acts in all respects, with the decision-making capabilities of a human expert.”

Expert system is highly specialized piece of software that attempts to duplicate the function of an expert.

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Expert SystemThe program (Expert System) acts an

intelligent consultant or advisor in the domain of interest, capturing the knowledge of one or more experts.

An Inference means a conclusion drawn from data.

Most of the expert systems in the market today are the prototypes and laboratory experiments.

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Structure of Expert System

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Structure of Expert System

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Knowledge BaseExplicit (well defined) & Human

ReadableEditablePreserve Knowledge of Experts

Knowledge RepresentationRules

Fixed PartGeneric rules

Dynamic PartProblem Specific Data

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Knowledge BaseThe knowledge base (also called rule base

when If-then rules are used) is a set of rules which represents the knowledge about the domain.

The general form of a rule is: If cond1 and cond2 and cond3 ... { then action1, action2, ... }

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Inference EngineAn inference engine is a computer

program that tries to derive answers from a knowledge base.

It is the "brain" that expert systems use to reason about the information in the knowledge base for the ultimate purpose of formulating new conclusions.

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Inference EngineThe inference engine is the program

part of an expert system.

It represents a problem solving model which uses the rules and the situation-specific knowledge in the knowledge base to solve a problem.

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User InterfaceThe front end that enables to

communicate with the inference engine & knowledge base is called the User Interface of an expert system.

Text Based (using commands).Menu Based (Graphical User

Interface).

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Working MemoryWorking memory is the global database of facts used by rules of knowledge base.

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Rule-Based Expert System

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Types of Expert SystemFollowing is a list of major types of Expert

System: Diagnosis Repair Instruction Interpretation Prediction Design & Planning Monitoring & Control

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DiagnosisDiagnosis types of expert systems are used to recommend remedies to illnesses, trouble-shoot electronic or mechanical problems or as debugging tools.

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RepairExpert systems that define repair

strategies are also very common.

As well as diagnosing the problem, they can suggest a plan for the repair of the item.

Such systems have been employed in the automotive repair field and similar areas.

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InstructionInstructional expert systems have

been used for training or instruction in a particular field.

This system presents material in an order determined by its evaluation of the user’s ability and current knowledge and monitor’s the progress of the student, altering the sequence depending on this progress.

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InterpretationInterpretive expert systems have the

ability to analyze data to determine its significance or usefulness.

The knowledge base often contains models of real world situations which it compares to its data.

These are often used in exploration for mineral, gas and oil deposits as well as in surveillance, image analysis and speech understanding.

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PredictionPredictive expert systems are used

as a method to “guess” at the possible outcomes of observed situations, usually providing a probability factor.

This is used often in weather forecasting.

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Design & PlanningThis allows experts to quickly

develop solutions that save time.These systems do not replace

experts but act as a tool by performing tasks such as costing, building design, material ordering, etc.

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Monitoring & ControlIn certain applications, expert systems

can be designed to monitor operations and control certain functions.

These are particularly useful where speed of decision making is vitally important, for example in the nuclear energy industry, air traffic control and the stock market.

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Knowledge EngineeringThe process of building an expert system:

The knowledge engineer establishes a dialog with the human expert to elicit knowledge.

The knowledge engineer codes the knowledge explicitly in the knowledge base.

The expert evaluates the expert system and gives a critique to the knowledge engineer.

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Development of an Expert System

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The End (Part - 1)

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