FT228/4 Knowledge Based Decision Support Systems

Rule-Based Systems

Ref: Artificial Intelligence A Guide to Intelligent Systems

Michael Negnevitsky – Aungier St. Call No. 006.3

Knowledge

Knowledge is a theoretical or practical understanding of a particular doaminKnowledge is the sum of what is currently knowThose who possess knowledge are termed experts

Knowledge

What is an expert ?Deep knowledgeStrong practical experienceHow do you represent how experts think?

Knowledge Representation

Programming language is a means of representing knowledgeProcedural knowledge “how to” Knowledge about how to perform

some task

Declarative knowledge “what is “

Knowledge Representation

Production Rules IT-THEN expressions

IF some condition(s) exists THEN perform some action(s)Test-Action rulesRule-Based System = Intelligent Production System

Knowledge Representation

Rule Part 1 Antecedent (premise or condition) IF part Test part

Rule Part 2 Consequent (conclusion or action) THEN part Action part

IF <antecedent> THEN <consequent>A rule fires when its condition part is satisified and its action part is executed

Knowledge Representation

Rule can have multiple antecedents Conjunction AND Disjunction OR Or a combination of both

Consequent can have multiple clauses IF <antecedent> THEN <consequent1>

<consequent2>

<consequentn>

Knowledge Representation

Antecedent consists of An object (linguistic object) Its value

Linked by an operator Identifies the object and assigns the value E.g is, are, is not, are not Mathematical operators e.g =, >, <

Consequent consists of An object A value Connected by an operator

Knowledge Representation

Rules represent Relations Recommendations Directives Strategies Heuristics

Production System Model

Long Term Memory

Production Rule

Short Term Memory

Fact

Reasoning

Conclusion

Rule-Based System for Tic-Tac-Toe

What rules do we need ?Rules may have tests that are satisfied at the same time – need some mechanism for selecting right rule