EXPERT SYSTEM EXPERT SYSTEM . An Expert system is known as Knowledge based system is a computer program that contain some of the subject specific knowledge of one or more human experts. It uses question answers, logical reasoning to get the solution of a problem. An expert system is an interactive computer based decision tool that uses both facts and heuristics to solve difficult problems based on knowledge acquired from an expert.

An expert system operates as an interactive system that respond to questions ,asks for clarification , makes recommendations and generally aids the decision making process

Architecture of EXPERT SYSTEM

EXPERT SYSTEM

Levels of Expert System

Need of an Expert SystemWHY EXPERT SYSTEM ??????????????

Expert systems are necessitated by the limitations associated with conventional human decision making processHumans get tired from physical and mental workload.Humans lie , hide and die.Humans are unable to retain large amount of data in memory.Humans have limited working memory.Humans are slow in recalling information stored in memory.

Features of Expert SystemMultiple result orientedConclusion basedQuestion answered BasedLogical ReasoningSpecific Knowledge rather than specific Technique

Working of expert system Respond to questionsAsks for clarificationMakes recommendationsLogical Structure

What is Inference RuleAn inference rule is a rule made up of If clause and then clause. It is used to make a decision .If the condition is true, the loop will enter into If loop otherwise if statement is false, the loop will enter into ELSE loop.

The Inference Engine accepts user Input queries and responses to questions through user interface and uses the dynamic information and static information (the rules and facts ) stored in the knowledge base.

The inferring process is carried out in three stages MATCH SELECT EXECUTE

If then Else ClauseIf she is beautiful then If She is Highly Educated then If she ready to settle in Abroad then MATCH Found else she is beautiful, educated but not willing to settle abroad so MATCH FOUND end If else she is Beautiful but not Educated so,MATCH NOT FOUND End If else she is not beautiful , MATCH NOT FOUND End If

Output of Inference RuleAt each step of If else Clause, a conclusion is drawn which leads to formation of another conclusion till the final goal is Reached

EXPERT SYSTEMS

Process Multiple Values for any problem Parameter

PROBLEM :If a User is Hunting for any Pizza Outlet Results will be:DominosPizza HutSlice of ItalySabberrosPizza CornerNarula

Features of Expert SystemMultiple result orientedConclusion basedQuestion answered BasedLogical ReasoningSpecific Knowledge rather than specific Technique

Backward Chaining and Forward ChainingForward chaining moves from known state to goal state. Forward Chaining starts with the data available and uses the interference rules to conclude more data until a desired goal is reached.It is Data Driven TechnologyAn interface Engine using forward chaining searches the interface rules until it finds one in which the if clause is true. After If clause is true, after that then clause is concluded and information is added to data. Backward Chaining usually moves from Goal state to Original State. Backward Chaining starts with a list of goals and works backward to see if there is data which will allow to conclude any of these goals.It is Goal Driven Technology

An Interface engine using backward chaining would search the inference rules until it finds one which has a then clause that matches the desired goal

Forward ChainingENCOURAGED (student)->MOTIVATED (student)MOTIVATED (student) &HEALTHY (student)->WORKHARD (student)WORKHARD (student) & HASGOAL (student) ->EXCELL (student)EXCELL (student) -> SUCCEDD (student)

As in example : we can chain forward to show that when student is encouraged , is healthy and has some goals, the student will suceed.

BACKWARD CHAINING

Patient (NOT WELL)->Patient (BLOOD TEST)Patient (Not well and INFECTION DETECTED)-> PATIENT(REPORTS CONCLUDED)- PATIENT(SWINEFLU DETECTED)

Thfis process of setting up sub goals to confirm a goal continues until all the sub goals are eventually satisfied or fail. If satisfied , the backward chain is established thereby confirming the main goal

END USER Interactive DialogThis system is leading the user through a set of questions to achieve the solution.There is an interactive dialog system between User .Answers are usually given in the form of yes or No .Even sometimes the answer is given in the form of 1 and 0. 1 indicates yes answer 0 indicates No.Another major difference is that Expert systems usually accept answers in form odif YES and NO whereas Traditional System will accept the where questions and answers in form of Why, where, whose , then etc.

APPLICATIONSLocation of Faults in computer and communication systemsIdentifications of Chemical Compound structures and Chemical compounds.Planning experiments in biology, Chemistry and molecular genetics.Stock and bond portfolio selection and management system.Estate planning for minimal taxation and other specified goals.Numerous area of law including civil case evaluation, product liability, assault and battery and general assistance in locating different law precedents.Numerous applications related to space planning and explorationForecasting Crop DamageDifferent type of Medical Diagnosis (internal medicine, pulmonary diseases, infectious blood diseases and so on )

ExamplesDENDRAL The first expert system to be completed was DENDRAL, developed STANFORD university in the late 1960s. This system was capable of determining the structure of Chemical compounds given a specifications of the compound constituent elements and mass spectrometry data obtained from the samples of compound.

MYCIN It is an expert system which diagnosis infection blood diseases and determines a recommended list of therapies for the patient.

ApplicationsMedical DiagnosisEquipment RepairInvestment AnalysisVehicle RoutingContract BiddingProduction Control and Training