chapter02 - Chapter 2: The Representation of Knowledge...

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Chapter 2: The Representation of Knowledge Expert Systems: Principles and Programming, Fourth Edition
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Expert Systems: Principles and Programming, Fourth Edition 2 What is the study of logic? Logic is the study of making inferences – given a set of facts, we attempt to reach a true conclusion. An example of informal logic is a courtroom setting where lawyers make a series of inferences hoping to convince a jury / judge . Formal logic (symbolic logic) is a more rigorous approach to proving a conclusion to be true / false.
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Expert Systems: Principles and Programming, Fourth Edition 3 Why is Logic Important We use logic in our everyday lives – “should I buy this car”, “should I seek medical attention”. People are not very good at reasoning because they often fail to separate word meanings with the reasoning process itself. Semantics refers to the meanings we give to symbols.
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Expert Systems: Principles and Programming, Fourth Edition 4 The Goal of Expert Systems We need to be able to separate the actual meanings of words with the reasoning process itself. We need to make inferences w/o relying on semantics. We need to reach valid conclusions based on facts only.
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Expert Systems: Principles and Programming, Fourth Edition 5 Knowledge vs. Expert Systems Knowledge representation is key to the success of expert systems. Expert systems are designed for knowledge representation based on rules of logic called inferences. Knowledge affects the development, efficiency, speed, and maintenance of the system.
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Expert Systems: Principles and Programming, Fourth Edition 6 Arguments in Logic An argument refers to the formal way facts and rules of inferences are used to reach valid conclusions. The process of reaching valid conclusions is referred to as logical reasoning.
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Expert Systems: Principles and Programming, Fourth Edition 7 How is Knowledge Used? Knowledge has many meanings – data, facts, information. How do we use knowledge to reach conclusions or solve problems? Heuristics refers to using experience to solve problems – using precedents. Expert systems may have hundreds / thousands of micro-precedents to refer to.
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Expert Systems: Principles and Programming, Fourth Edition 8 Epistemology Epistemology is the formal study of knowledge . Concerned with nature, structure, and origins of knowledge.
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Expert Systems: Principles and Programming, Fourth Edition 9 Categories of Epistemology Philosophy A priori A posteriori Procedural Declarative Tacit
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Expert Systems: Principles and Programming, Fourth Edition 10 A Priori Knowledge “That which precedes” Independent of the senses Universally true Cannot be denied without contradiction
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Expert Systems: Principles and Programming, Fourth Edition 11 A Posteriori Knowledge “That which follows” Derived from the senses Now always reliable Deniable on the basis of new knowledge w/o the necessity of contradiction
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This note was uploaded on 05/12/2010 for the course IT expert sys taught by Professor Dr. during the Spring '10 term at Dubai Aerospace Enterprise University.

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chapter02 - Chapter 2: The Representation of Knowledge...

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