Expert_Systems.ppt

1、Expert Systems,ICT IGCSE,Objectives,Understand the use of expert systems in Mineral prospecting Car engine fault diagnosis Medical diagnosis Oil/mineral prospecting Plant/animal identification Strategy games eg Chess,What is an Expert System?,An expert system is computer software that attempts to ac

2、t like a human expert on a particular subject area. Expert systems are often used to advise non-experts in situations where a human expert is unavailable (for example it may be too expensive to employ a human expert, or it might be a difficult to reach the location).,Examples of expert systems inclu

3、de,Diagnosing a persons illness Diagnostics (car engine faults, circuit board faults etc) Prospecting for oil and minerals Tax and financial calculations Chess games Identification of plants, animals, chemical compounds Road scheduling for delivery vehicles,Contents of an Expert System?,An expert sy

4、stem is a knowledge-based system which attempts to replace a human expert in a particular field. The system will consist of a large database of knowledge facilities for searching the knowledge database a set of rules for making deductions from the data An engine to apply those rules (inference engin

5、e),Structure,User Interface,This is the system that allows a non-expert user to query (question) the expert system, and to receive advice. The user-interface is designed to be a simple to use as possible.,The knowledge base,This is a collection of facts. The knowledge base is created from informatio

6、n provided by human experts.,It is a database designed to allow the complex storage and retrieval requirements of the expert systems,The rules base,This is made up of a series of inference rules IF the country is in South America AND the language is Portuguese, THEN the country must be Brazil These

7、inference rules are used by the inference engine to draw conclusions. The inference rules closely follow human reasoning.,The inference engine,This acts rather like a search engine, examining the knowledge base for information that matches the users query. It is software that attempts to derive answ

8、ers from the knowledge base using a form of reasoning.,How it works:,How it works:,The non-expert user queries the expert system. This is done by asking a question, or by answering questions asked by the expert system. The inference engine uses the query to search the knowledge base and then provide

9、s an answer or some advice to the user.,Where Are Expert Systems Used?,Medical diagnosis (the knowledge base would contain medical information, the symptoms of the patient would be used as the query, and the advice would be a diagnose of the patients illness),Where Are Expert Systems Used?,Playing s

10、trategy games like chess against a computer (the knowledge base would contain strategies and moves, the players moves would be used as the query, and the output would be the computers expert moves),Where Are Expert Systems Used?,Providing financial advice - whether to invest in a business, etc. (the

11、 knowledge base would contain data about the performance of financial markets and businesses in the past),Where Are Expert Systems Used?,Helping to identify items such as plants / animals / rocks / etc. (the knowledge base would contain characteristics of every item, the details of an unknown item w

12、ould be used as the query, and the advice would be a likely identification),Where Are Expert Systems Used?,Helping to discover locations to drill for water / oil (the knowledge base would contain characteristics of likely rock formations where oil / water could be found, the details of a particular

13、location would be used as the query, and the advice would be the likelihood of finding oil / water there),Where Are Expert Systems Used?,Helping to diagnose car engine problems (like medical diagnosis, but for cars!) Two types: Onboard In workshops,Can Expert Systems Make Mistakes?,Human experts mak

14、e mistakes all the time (people forget things, etc.) so you might imagine that a computer-based expert system would be much better to have around.,Advantages of Expert Systems,An ES can store far more information than a human. Expert systems provide consistent answers. ES does not forget to ask impo

15、rtant questions, or make mistakes. Reduces the time taken to solve a problem Data can be kept up-to-date.,Data can be collected from many experts The expert system is always available 24 hours a day and will never retire. The system can be used at a distance over a network. A less skilled workforce

16、is needed,Opportunity to save money People/areas can access expertise they couldnt otherwise afford,Disadvantages of Expert Systems,Very expensive to set up in the first place The computers reasoning is only as good as the rules it has been given They have no common sense (a human user tends to notice obvious errors, whereas a computer wouldnt),Errors in the knowledge base can lead to incorrect decisions being made Mistakes made when entering