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Artificial Intelligence. Rule-based expert systems Lecture Eight. Road Map. We will discuss the followings: What is knowledge? Expert Systems (ES). Rule-based Expert Systems. Development team in Expert Systems. Rule-based Expert Systems structure. The course final exam!!.
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Artificial Intelligence Rule-based expert systems Lecture Eight
Road Map • We will discuss the followings: • What is knowledge? • Expert Systems (ES). • Rule-based Expert Systems. • Development team in Expert Systems. • Rule-based Expert Systems structure. • The course final exam!!
What is knowledge? Knowledge is a theoretical or practical understanding of a subject or a domain. Knowledge is also the sum of what is currently known.
Who is acknowledged as an expert? • An expert has the followings: • A deep knowledge (of both facts and rules) • And strong practical experience in a particular narrow domain. • In general, an expert is a skilful person who can do things other people cannot.
How do experts think? • Experts express their knowledge in the form of rules for problem solving. Imagine, you meet an alien! He wants to cross a road. Can you help him?
How do experts think? – Cont. IF the ‘traffic light’ is green THEN the action is go IF the ‘traffic light’ is red THEN the action is stop A rule provides some description of how to solve a problem.
Expert System • As soon as knowledge is provided by a human expert, we can input it into a computer. • We expect the computer to solve a problem that have to be solved by an expert. • To be able to integrate new knowledge. • To be able to show its knowledge in a form that is easy to read and understand (i.e. Natural Language). • To be able to explain how it reaches a particular conclusion.
Expert system An expert system is a computer program capable of performing at the level of a human expert in a narrow problem area.
Expert system Shells • A large number of companies produce software for rule-based expert system development . • Can be considered as an expert system with the knowledge removed. • Their main advantage is that the system builder concentrate on the knowledge itself rather than on learning a programming language.
Expert system Shells – Cont. • Examples for available free and commercial Expert System Shells • Aion • Attar • CLIPS • Corticon • drools • See the following link for a longer list • http://www.kbsc.com/rulebase.html
Expert System Development Team In general, there are five members of the expert system development team
Development Team Project Manager Domain Expert Knowledge Engineer Programmer Expert System End User
The production model Long-term memory Short-term memory Rules Facts Reasoning Conclusion
Structure of a rule-based ES Knowledge base Database Rule: IF-THEN Fact Inference Engine Explanation facilities User Interface User
Fundamental characteristics of an expert system • High-quality performance. • Good speed in reaching a solution. • Apply heuristics to guide the reasoning to reduce the search area for a solution. • Explanation capability.
Advantages of rule-based expert systems • Natural knowledge representation. • Uniform structure. • Separation of knowledge from its processing. • Dealing with incomplete and uncertain knowledge.
Disadvantages of rule-based expert systems • Opaque relations between rules. Related to • The lack of hierarchical knowledge representation. • Ineffective search strategy. • Inability to learn. Human expert, knows when to ‘break the rules’.
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