tailieunhanh - AUTOMATION & CONTROL - Theory and Practice Part 14

Tham khảo tài liệu 'automation & control - theory and practice part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 316 AUTOMATION CONTROL - Theory and Practice 4 component_X_bad_quality IF crumbs_in_material These rules constitute only a small section of a diagnosis knowledge base for a real world application. The causes of symptoms are situated on the left side of the IF statement while the symptoms itself are positioned on the right side. This is in opposite direction of the causal direction. The results of the application of the reasoning algorithms are the conclusions of the rules on the left-hand side of the IF statement and the result should be by definition the cause of symptoms. The syntax of the propositional logic has been defined in various books like Kreuzer and Kuhling 2006 Russel and Norvig 2003 or Poole et al. 1998 . Propositional formulae deal only with the truth values TRUE FALSE and a small set of operations is defined including negation conjunction disjunction implication and bi-conditional relations. The possibility to nest formulae enables arbitrary large formulae. The HLD restricts the propositional logic to Horn-logic which is not a big limitation. A Horn formula is a propositional formula in conjunctive normal form a conjunction of disjunctions in which each disjunction contains in maximum one positive literal. The set of elements of these disjunctions is also called a Horn clause. A set of Horn clauses build a logic program. If a Horn clause contains exactly one positive and at least one negative literal then it is called a rule. The positive literal is the conclusion or head of the rule while the negative literals constitute the condition part or the body of the rule. If a rule is part of a HLD file then we call it a HLD rule. The form of horn clauses is chosen for the HLD since there exist an efficient reasoning algorithm for this kind of logic - namely the SLD resolution. This resolution algorithm may be combined with the breadth-first search BFS or with the depth-first search DFS strategy. Breadth-first search The algorithm proves for each rule .